Protector Trip Relays

250 Series DIN Rail and Wall Mounted

Protectors
Our protector trip relays offer
continuous surveillance of
electrical parameters. When
the monitored parameter
moves outside the set point
limit, the relay operates.

A.C. and D.C. voltage

A.C. and D.C. current
Over half a million Protector units
Frequency have been tried and tested, in
Phase sequence many industrial environments.

Phase failure Successfully used in alarm

Phase balance protection and control functions,
typically in 3 phase electrical
Thermistor
power systems, control panels &
Thermocouple gensets.
Transducer
Specification
Millivolt trips
Safety Requirements: U.S. Standard, IEC 414 Burden: 4VA maximum
Hot spot relays Temperature Range: 0°C to 60°C (0°C to +40°C for Output Relay Type: D.P Changeover
UL approval) Ratings:
Speed sensing
Storage Temperature: -20°C to 70°C A.C.: 240V, 5A non-inductive
Synchro-check relays Temp. Co-efficient: 0.05% per °C D.C.: 24V, 5A resistive
Interference Immunity: Electrical stress surge Operations: 0.2 million at the above loads
Reverse power withstand and non function to Reset: Automatic
ANSI/IEEE C37 90a
R.O.C.O.F. vector shift Weight: 252 case - approx 0.4Kg
Enclosure Code: IP50 to BS5490, IEC 529 253 case - approx 0.6Kg
Calibrated at: 23°C 256 case - approx 1.0Kg
Auxiliary: Approvals: File Number E113067
A.C. 50/60Hz: 110, 120, 230, 240, 400 or (where applicable)
415, or 440V + 20%
Max. D.C. Load Breaking Capacity D.C.: 12, 24, 48, 110, 125, 135V File Number LR52592
with resistive load (maximum 156V D.C.) + 15% (where applicable)
Maximum ripple 15%
Bureau Veritas (BV)
File No: 2650H-07427-A0
PRSOBV (where applicable)
ABS American Bureau of
Shipping (where applicable)

Casing Ordering Information

All products can be DIN rail or wall mounted. Please quote:
1. Product Code
253 and 256 cases have screw holes to facilitate
2. Function i.e. Under or Over
wall mounting.
3. Relays normally de-energize on under trip and
252 cases are supplied with an adaptor plate for energize on over trip. Please specify standard or
wall mounting. non standard trip, because standard relays are
configured for a fail safe.
All products are supplied with a clear terminal 4. System Voltage and/or Currents where applicable
cover/anti-tamper cover, manufactured from flame 5. System Frequency
retardent polycarbonate. 6. Auxiliary Voltage where required
7. Preset Differential where required
8. Time delay where applicable
9. On temperature trips quote temperature span &
sensor type and set points and trip temperatures

Protector Relays
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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
A.C. Current
The Crompton A.C. current protectors
provide continuous surveillance of the
monitored circuit. When the current moves
outside the setpoint limit, the relay
operates.
An illuminated LED indicates when the relay
Features is energized.

Adjustable setpoint For 3 phase systems, the sequence of

connection is not important.
Adjustable differential
The Protector can be used to monitor:
Internal time delay
• Over and Under current conditions
LED trip indication
• Load detection
2 pole relay contacts
• Monitoring of electric heating systems

Introduction
Crompton A.C. Current Protectors provide the monitored signal moves outside of the
continuous surveillance of the monitored circuit. setpoint limit, a trip will occur. An adjustable
These products offer user adjustable trip point time delay is provided to prevent the relay from
Application (setpoint) and time delay settings. The setpoint tripping for a predetermined period to prevent
adjustment range is between 40% and 120% of nuisance tripping. The units draw their operating
General application for
the nominal current. Input currents can be via power from a separate auxiliary supply input.
any electrical load,
current transformers or direct up to 10A. An Single phase and three phase products are
monitoring for under load internal differential setting of 1% reduces available. Three phase products monitor the
and over load conditions nuisance tripping if the measured signal is noisy current level for each phase, and are not phase
Motors - to monitor for or unstable. When the measured current moves sequence sensitive. Combined units offer under
outside the setpoint limit, the relay will operate, and over current trips in one compact unit.
conditions such as
giving an alarm or initiation signal. As soon as Single function units are also available.
overload, locked rotor and
short circuit
Gensets - to ensure load Product Function
current is within generator
capacity Over current models: When the monitored Under current models: When the monitored
current exceeds the setpoint, the relay will current falls below the setpoint, the relay will
Machinery - detecting energize and the red LED will illuminate to de-energize and the red LED will extinguish to
broken drive belts on indicate the trip condition. The relay will indicate the trip condition. The relay will
machinery automatically reset once the monitored current automatically reset once the monitored current
falls below the setpoint minus the differential. rises above the setpoint plus the differential.
When reset, the LED will extinguish and the When reset, the LED will illuminate and the
relay de-energizes. relay energizes.

Product customisation options

Please contact the factory.

• Adjustment ranges - different adjustment • Relay operation - standard models are fail
ranges are possible for the setpoint and safe, but the relays can be customised to
differential controls energise or de-energise on trip

Protector Relays 20
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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
A.C. Current

Specification
Approvals: U.L. recognized up to 300V Range: 40 to 120% of nominal
CSA approved up to 240V current. Customised
adjustment range to order
Nominal current: 1A or 5A from C.T. secondary
other values between 0.2 and Time Delay: 0 to 10 seconds adjustable
10A to order other values to order
Frequency: 50, 60 or 400 Hz Auxiliary Supply:
C.T. Burden: 0.5VA per phase A.C. 50/60Hz: 100, 110, 120, 208, 220,
240, 480V, ±20%
Overloads: 2 x rating continuously
10 x rating for 3 seconds D.C.: 12, 24, 48, 110 or 125V, ±15%
maximum ripple 15%
Set Point Repeatability: 0.5% of full span
Burden: 4VA maximum
Differential: Preset at 1%
Other values 1 to 10% to order

Product Code Examples

A.C. Current A.C. Input A.C. Aux Power Protection ANSI No. Catalogue No.

Single Phase 5A 120V Under current 40-120% 37 252-PAUU-LSBX-C6-DG-D1-EB

Single Phase 5A 120V Over current 40-120% 51 252-PAOU-LSBX-C6-DG-D1-EA
Single Phase 5A 120V Under & over current 37/51
(2 output relays) 253-PADU-LSBX-C6-DG-D1-EC
3 Phase 3⁄4 Wire 5A 120V Under current 37 253-PAVU-LSBX-C6-DG-D1-EB
3 Phase 3⁄4 Wire 5A 120V Over current 51 253-PAPU-LSBX-C6-DG-D1-EA

Connection Diagrams

252-PAU 253-PAD
252-PAO Relay Under Relay Over Relay
Contact Set 1 Contact Set 2 Input Contact Set 1 Contact Set 1

Input Supply Under Relay Supply Over Relay

Contact Set 2 Contact Set 2
253-PAP
253-PAV
Input Input Input
1 2 3

Note: The neutral connection is always

required on 4 wire products.

Relay Supply Relay

Contact Set 1 Contact Set 2

Protector Relays
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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
A.C. Voltage with Adjustable Differential

The Crompton A.C. Voltage Protectors provide

continuous surveillance of the monitored
circuit. When the measured voltage moves
outside the setpoint limit, the relay will operate
giving an alarm or initiation signal.

Features An illuminated LED indicates when the relay is

energized. The 3 phase, 3 or 4 wire models,
Adjustable setpoint protect each phase independently. The
Protector can be used to protect for:
Adjustable differential
• Under and Over voltage detection
Internal time delay
• Start standby generators
LED trip indication
• Operation of mains failure units
2 pole relay contacts
• Switching standby supplies

Introduction
Crompton A.C. Voltage Protectors provide A fixed time delay is available as a factory
continuous surveillance of the monitored option, preventing the relay from tripping for a
voltage circuit. These products offer user predetermined period to prevent nuisance
Application adjustable trip point (setpoint) and differential tripping.
(hysteresis) settings. The setpoint adjustment
Gensets - to monitor The units draw their operating power from the
range is 25%, operating between 75% and
correct operation of the measuring inputs, although a separate
100% of the nominal supply for under voltage
AVR (Automatic Voltage units, and between 100% and 125% for the
auxiliary supply input option is available on
Regulator) and excitation some models. Single phase and three phase
over voltage units. The differential setting
system products are available. Three phase products
adjustment range is 15%, and it can be used
monitor the voltage level for each phase, and
to reduce nuisance tripping if the measured
Motors - some electric are not phase sequence sensitive.
signal is noisy or unstable. When the
motors are voltage measured Voltage moves outside the setpoint Combined units offer under and over voltage
sensitive, and can limit, the relay will operate, giving an alarm or trips in one compact unit. Single function
overheat and burn out initiation signal. units are also available.
when operated at low
As soon as the monitored signal moves
voltages
outside of the setpoint limit, a trip will occur.
UPS supplies - when the
main A.C. supply falls
outside the acceptable Product Function
operating voltage window, Over voltage models: When the monitored Under voltage models: When the monitored
the relay can initiate a voltage exceeds the setpoint, the time delay voltage falls below the setpoint, the time
change over to an is started. When the time has elapsed, the delay is started. When the time has elapsed,
alternate or standby relay will energize and the red LED will the relay will de-energize and the red LED will
supply illuminate to indicate the trip condition. The extinguish to indicate the trip condition. The
relay will automatically reset once the relay will automatically reset once the
monitored voltage falls below the setpoint monitored voltage rises above the setpoint
minus the differential. When reset, the LED plus the differential. When reset, the LED will
will extinguish and the relay de-energizes. The illuminate and the relay energizes. The time
time delay is not active when resetting. delay is not active when resetting.

Product customisation options

Please contact the factory.
• Time delay - internal fixed time delay • Adjustment ranges - different adjustment
before a trip occurs ranges are possible for the setpoint and
• Separate auxiliary supply - sometimes differential controls
required to maintain a time delay or • Relay operation - standard models are fail
energised relay when the monitored signal safe, but the relays can be customised to
fails energise or de-energise on trip

Protector Relays
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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
A.C. Voltage with Adjustable Differential

Specification
Approvals: U.L. recognized up to 300V Differential: Adjustable range 1-15%
CSA approved up to 240V
Range Adjustment: Under Voltage: 75 to 100%
Nominal Voltage: 100, 110, 120, 208, 220, Over Voltage: 100 to 125% of
280, 270, 400, 415, 440V nominal input voltage

System Frequency: 45/65Hz or 360/440Hz Time Delay Option: Factory preset internal delay
up to 30 seconds. Specify at
Overload: 1.2 x continuously time of ordering
1.5 x for 10 x 10 seconds
Burden: 3VA approx.
Setpoint Repeatability: Better than 0.5%

Product Code Examples

A.C. Voltage Protection ANSI No. Catalogue No.

Single Phase 120V L-N Under Voltage 75-100% 27 252-PVUU-PQBX-C6-EB

Over Voltage 100-125% 59 252-PVOU-PQBX-C6-EA
Over and Under Voltage (2 output relays) 27/ 59 253-PVBU-PQBX-C6-EC
3 Phase 3 Wire 120V L-L Under Voltage 75-100% 27 252-PVKU-PQBX-C6-EB
Over Voltage 100-125% 59 252-PVAU-PQBX-C6-EA
Over and Under Voltage (2 output relays) 27/ 59 253-PVMU-PQBX-C6-EC
3 Phase 4 Wire 120V L-N Under Voltage 75-100% 27 252-PVVU-PQBX-C6-EB
Over Voltage 100-125% 59 252-PVPU-PQBX-C6-EA
Over and Under Voltage (2 output relays) 27/ 59 253-PVEU-PQBX-C6-EC

Connection Diagrams
252-PVU 253-PVB
252-PVO
Relay Under Relay Over Relay
252-PVV Contact Set 1 Contact Set 2 Contact Set 1 Contact Set 1
252-PVP
252-PVK
252-PVA

3 Phase Input Aux supply Under Relay Input Over Relay

L N when Contact Set 2 Contact Set 2
Single Phase Input required

253-PVE
253-PVM
Input

Note: The neutral connection is always

required on 4 wire products.

Input

Protector Relays
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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
A.C. Voltage with Adjustable Time Delay

The Crompton A.C. Voltage Protectors provide

continuous surveillance of the monitored circuit.
When the measured voltage moves outside the
setpoint limit, the relay will operate after the
Features selected time delay, giving an alarm or initiation
signal. Relays normally energize on overvolts and
Adjustable setpoint de-energize on undervolts. An illuminated LED
indicates when the relay is energized. The
Adjustable time delay
Protector can be used to protect for:
Internal differential
• Under and Over voltage
LED trip indication • Start up standby generators
2 pole relay contacts • To operate mains failure units
• Switching standby supplies
• Protecting computer supplies
• Where close voltage control is required

Application
Gensets - to monitor Introduction
correct operation of the
AVR (Automatic Voltage Crompton A.C. Voltage Protectors provide The time delay prevents the relay from
continuous surveillance of the monitored tripping for a predetermined period to prevent
Regulator) and excitation
voltage circuit. These products offer user nuisance tripping.
system adjustable trip point (setpoint) and time delay
The products also feature an internal
Motors - some electric settings. The setpoint adjustment range is
differential (hysteresis) setting of 1% to
motors are voltage 25%, operating between 75% and 100% of
reduce nuisance tripping if the measured
the nominal supply for under voltage units,
sensitive, and can signal is noisy or unstable.
and between 100% and 125% for the over
overheat and burn out voltage units. The time delay setting The units draw their operating power from the
when operated at low adjustment range is typically 0 to 10 measuring inputs, although a separate
voltages seconds, although longer delays are auxiliary supply input option is available on
available. some models. Single phase and three phase
UPS supplies - when the
main A.C. supply falls products are available. Three phase products
As soon as the monitored signal moves
monitor the voltage level for each phase, and
outside the acceptable outside of the setpoint limit, the time delay is
are not phase sequence sensitive.
operating voltage window, activated, after which a trip will occur.
the relay can initiate a
change over to an
alternate or standby
supply
Product Function
Over voltage models: When the monitored Under voltage models: When the monitored
voltage exceeds the setpoint, the time delay voltage falls below the setpoint, the time
is started. When the time has elapsed, the delay is started. When the time has elapsed,
relay will energize and the red LED will the relay will de-energize and the red LED will
illuminate to indicate the trip condition. The extinguish to indicate the trip condition. The
relay will automatically reset once the relay will automatically reset once the
monitored voltage falls below the setpoint monitored voltage rises above the setpoint
minus the differential. When reset, the LED plus the differential. When reset, the LED will
will extinguish and the relay de-energizes. The illuminate and the relay energizes. The time
time delay is not active when resetting. delay is not active when resetting.

Protector Relays
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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
A.C. Voltage with Adjustable Time Delay

Product customisation options

Please contact the factory.
• Adjustment ranges - different adjustment • Differential - internally fixed value between
ranges are possible for the setpoint and 1% and 15%
differential controls • Relay operation - standard models are fail
• Separate auxiliary supply - sometimes safe, but the relays can be customised to
required to maintain a time delay or energise or de-energise on trip
energised relay when the monitored signal
fails

Specification
Nominal Voltage: 100, 110, 208, 220, 240, Differential: Preset at 1%
277, 400, 415, 440, 480V Other values 1% to 10% order

System Frequency: 45/65Hz or 360/440Hz Range: Adjustable Under Voltage 75

to 100% Over Voltage 100 to
Overload: 1.2 x continuously 125% of nominal input voltage
1.5 x for 10 x 10 seconds
Time Delay: Adjustable up to 10 seconds
Burden: 3 VA

Setpoint Repeatability: Better than 0.5%

Product Code Examples

A.C. Voltage Input Protection ANSI No. Catalogue No.

Single Phase 120V L-N Under voltage 75-100% 27 252-PVZU-PQBX-C6-EB-T1

Single Phase 120V L-N Over voltage 100-125% 59 252-PVHU-PQBX-C6-EA-T1
3 Phase 3 Wire 120V L-L Under voltage 75-100% 27 252-PVJU-PQBX-C6-EB-T1
3 Phase 3 Wire 120V L-L Over voltage 100-125% 59 252-PVCU-PQBX-C6-EA-T1
3 Phase 4 Wire 120V L-N Under voltage 75-100% 27 252-PVXU-PQBX-C6-EB-T1
3 Phase 4 Wire 120V L-N Over voltage 100-125% 59 252-PVSU-PQBX-C6-EA-T1

Connection Diagrams
252-PVZ 252-PVX
Relay Relay
252-PVH Contact Set 1 Contact Set 2 252-PVS Contact Set 1 Contact Set 2
252-PVC
252-PVJ

Input Aux supply Input Aux supply

when required when required

Protector Relays
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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Frequency

Features
Adjustable setpoint
Adjustable differential
LED trip indication
2 pole relay contacts

The Crompton frequency Protectors give Since speed is proportional to the

continuous surveillance of the monitored frequency, this protection can be used to
circuit. When the frequency moves protect for:
outside the set point limit the relay will • Over and Underspeed
operate giving an alarm, control or
• Standby supplies for Industrial,
tripping signal.
Hospital or Marine use
Application
An illuminated LED indicates when the • Mains supplies
Gensets - use these relays relay is energized.
• Computer supplies
to monitor correct
• Other control gear
operation of the engine
speed controller
(governer)
Motors - synchronous Introduction
motors rotate at speeds Crompton Frequency Protectors provide When the measured Frequency moves outside
proportional to line continuous surveillance of the monitored the setpoint limit, the relay will operate,
frequency. Use these circuit. These products offer user adjustable giving an alarm or initiation signal.
relays to ensure correct frequency trip point (setpoint) and differential
As soon as the monitored frequency moves
running speed (hysteresis) settings. The setpoint adjustment
outside of the setpoint limit, a trip will occur.
range is centred around the nominal 50Hz,
Standby supplies - when The units draw their operating power from the
60 Hz or 400Hz system frequency. The
the main A.C. supply falls measuring inputs.
differential setting adjustment can be used to
outside the acceptable reduce nuisance tripping if the measured Combined units offer under and over
working frequency, these signal is noisy or unstable. frequency trips in one compact unit. Single
relays can initiate a function units are also available.
change over to an
alternate or standby
supply
Product Function
Over frequency models: When the monitored Under frequency models: When the
frequency exceeds the setpoint, the relay will monitored frequency falls below the setpoint,
energize and the red LED will illuminate to the relay will de-energize and the red LED will
indicate the trip condition. The relay will extinguish to indicate the trip condition. The
automatically reset once the monitored relay will automatically reset once the
frequency falls below the setpoint minus the monitored frequency rises above the setpoint
differential. When reset, the LED will plus the differential. When reset, the LED will
extinguish and the relay de-energizes. illuminate and the relay energizes.

Protector Relays
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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Frequency

Product customisation options

Please contact the factory.

• Adjustment ranges - different adjustment • Relay operation - standard models are fail
ranges are possible for the setpoint and safe, but the relays can be customised to
differential controls energise or de-energise on trip
• Time Delay - internal fixed time delay
before a trip occurs

Specification
Approvals: U.L. recognized up to 300V Setpoint Repeatability: Better than 0.5%

Nominal frequency: 50, 60 or 400Hz Ranges (50Hz): 40/60Hz adjustable

System Voltage: 100, 110,120, 208, 220, Ranges (60Hz): 50/70Hz adjustable
230, 240, 277, 380, 400,
Differential: 0.1 to 3.0Hz adjustable
415, 440 or 480V ±20%
Range (40Hz): 360/440Hz adjustable
Overload: 1.2 x continuously
1.5 x for 10 x 10 seconds Differential: 10 to 30Hz adjustable
Burden: 3VA

Product Code Examples

Frequency Relay Input Protection ANSI No. Catalogue No.

Single Phase 120V A.C. Under frequency 55-65Hz 81U 252-PHUU-PQBX-C6-EB

Single Phase 120V A.C. Over frequency 55-65Hz 810 252-PHOU-PQBX-C6-EA
Single Phase 120V A.C. Under & Over (2 output relays) 810/U 253-PHDU-PQBX-C6-EC

Connection Diagrams
252-PHU 253-PHD
252-PHO Output Relay
Under Relay Over Relay
Contact Set 1 Contact Set 2 Contact Set 1 Contact Set 1

Input Under Relay Input Over Relay

Contact Set 2 Contact Set 2

Under or Over Frequency Combined Under and Over Frequency

Protector Relays
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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Combined Under/Over Voltage and Frequency

Features
Adjustable setpoint
Adjustable time delay
Internal differential
LED trip indication
2 pole relay contacts

The Crompton combined voltage & An illuminated LED indicates when the
frequency Protectors give continuous relay is energized.
Application surveillance of the monitored circuit.
This protector can be used to protect for:
When the voltage or frequency moves
Gensets - to monitor outside the set point limit the respective • Over and Underspeed
correct operation of the relay will operate giving an alarm, control
AVR (Automatic Voltage • Over and Under voltage
or tripping signal.
Regulator) and excitation
system and the engine
speed controller
(governer)
Introduction
Motors - some electric
The Crompton combined Voltage and As soon as the monitored signal moves
motors are voltage
Frequency Protectors provide the most outside of the setpoint limit, the time delay is
sensitive, and can popular relay functions in one convenient activated, after which a trip will occur. The
overheat and burn out package. The products offers user adjustable time delay prevents the relay from tripping for
when operated at low trip point (setpoint) for voltage and frequency, a predetermined period to prevent nuisance
voltages. Synchronous plus adjustable time delay settings. The tripping.
motors rotate at speeds setpoint adjustment range is 25%, operating
The products also feature an internal
proportional to line between 75% and 100% of the nominal
differential (hysteresis) setting of 1% to
frequency. Use these supply for under voltage, and between 100%
reduce nuisance tripping if the measured
relays to ensure correct and 125% for over voltage. The frequency
signal is noisy or unstable.
running speed setpoint adjustment range is centred around
the nominal 50Hz, 60 Hz or 400Hz system The product is available for single phase
UPS supplies - when the frequency.The time delay setting adjustment systems only, and draws its operating power
main A.C. supply falls range is typically 0 to 10 seconds, although from the measuring input.
outside the acceptable longer delays are available.
operating voltage window,
the relay can initiate a
change over to an
alternate or standby
supply Product Function
Over voltage & frequency: When the Under voltage & frequency: The relay will de-
monitored value exceeds the setpoint and the energize after the time delay has elapsed,
time delay has elapsed, the relay will energize and the red LED will extinguish to indicate the
and the red LED will illuminate to indicate the trip condition.
trip condition.

Protector Relays
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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Combined Under/Over Voltage and Frequency

Product customisation options

Please contact the factory.
• Adjustment ranges - different adjustment • Relay operation - standard models are fail
ranges are possible for the setpoint and safe, but the relays can be customised to
time delay controls energise or de-energise on trip
• Differential - internally fixed value between
1% and 15%

Specification
Approvals: U.L. recognized Relays:

Nominal Voltage: 120V A.C. 4 relays -Under voltage

Over voltage All 4 relays are DP changeover
Voltage Range: Over voltage100 to 125% Under frequency A.C. 240V 5A non inductive
Under voltage 75 to 100% Over frequency D.C. 24V 5A resistive
Differential: Fixed internally at 1% Operations: 0.2 million at the above loads
Time Delay: Adjustable between 1 and 30 Reset: Automatic
seconds
LEDS: Indicate condition of relay,
Frequency Ranges: 40-60Hz (50Hz) or i.e. illuminated when relays
50-70Hz (60Hz) energize. Relays will be
Differential: Fixed internally at 0.1Hz energized when the
voltage/frequency is within the
Time Delay: Adjustable between setpoint. Relays de-energize
1 and 30 seconds on trip point when the
voltage/frequency goes over
Set Point Repeatability: Better than 0.5%
or under the set point.
Voltage Withstand: 1.2 x continuously
1.5 x for 10 second
x 10 operations to BS6253

Product Code Example

Frequency Relay Input Protection ANSI No. Catalogue No.

Single Phase 120V 60Hz Over & Under Voltage 27/59 810/U 256-PHVU-PQBX-C6
Over & Under frequency (50-70Hz)
(4 independent double pole change over
relays; fixed differential and adjustable time
delay (factory set) between 1 & 30 seconds;
specify time delay when ordering)

Connection Diagram
256-PHV

Under Voltage Relay Over Voltage Relay Under Frequency Relay Over Frequency Relay
Contact Set 1 Contact Set 1 Contact Set 1 Contact Set 1

Input
Contact Set 2 Contact Set 2 Contact Set 2 Contact Set 2

Protector Relays
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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Phase Sequence and Phase Failure

Application: The Crompton phase sequence and phase

failure protector relays are designed to
Portable pumps monitor the correct phase rotation or
Portable compressors sequence of three phase, 3 or 4 wire,
supply systems for protection against
Motor driven mixing incorrect phase sequence, loss of one
equipment phase and under voltage.
Motors - Single Phasing
Gensets - correct engine
rotation
All portable equipment
All rotating machines

Introduction
Rotating machines are particularly vulnerable For permanent installations, this relay should
to incorrect phase sequence. Three phase be used to monitor the incoming supply,
motors can rotate in the wrong direction, protecting all equipment against incorrect
potentially leading to physical damage or the connection at initial installation or after
risk of injury to personnel, yet voltage and maintenance work. Rotating machines that
We also manufacture front of current readings may appear normal. If one cannot tolerate reverse rotation or pose
panel mounting phase phase is lost because of a blown fuse, significant risk to personnel under this
electric motors can continue to operate condition should be individually protected with
sequence indicators (single phasing) which can result in severe this relay. The possibility of incorrect supply
electrical or mechanical damage. connection is much more likely in portable
equipment or marine applications

Product Function
The protector continuously monitors the three Important note: If one phase is lost due to a
phase supply. With the correct phase blown fuse, some loads can re-generate the
sequence applied, the front panel LED will missing voltage. This relay can be used as a
illuminate and the output relay will be phase failure relay providing the regenerated
energized. An incorrect sequence or missing voltage in the open phase is less than 70% of
phase will de-energize the relay, and the LED the nominal supply voltage. If there is the
will be extinguished. If the supply drops below possibility of a higher regenerated voltage,
85% of its nominal voltage, this condition will the phase balance relay 252-PSF should be
also cause a trip. used.

Protection against Protection for

• Incorrect phase sequence • Portable electrical equipment
• Loss of one phase • Incorrect sequence connection
• Under voltage • Loss of one phase (which can result in
severe electrical/ mechanical damage or
physical/personnel damage due to reverse
rotation of motor driven equipment)

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Phase Sequence and Phase Failure

Specification
Approvals: U.L. recognized up to 300V Overload: 1.2 x continuously
CSA Approved up to 240V 1.5 x for 10 x 10 seconds to
Symmetric
Nominal Voltage: 100, 110, 120, 208, 220,
230, 240, 277, 380, 400, Undervoltage Protection:
415, 440 & 480V Preset at 85% of nominal

System Frequency: 50, 60, or 400Hz (specify) Weight: Approximately 0.4kg

Burden: 3VA approx.

Product Code Examples

Relay Input Protection ANSI No. Catalogue No.

3 Phase 3 or 4 wire 120V L-L 60 Hz Phase sequence, under voltage 47 252-PVRU-PQBX-C6

3 Phase 3 or 4 wire 415V L-L 60 Hz Phase sequence, under voltage 47 252-PVRU-SBBX-C6

Connection Diagrams

252-PVR
Relay
Contact Set 1 Contact Set 2

Note: No neutral connection is required

Input

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Phase Balance

The Crompton Protector Phase Balance

module provides continuous surveillance
of a 3 phase, 3 or 4 wire system and
Application: protects against:
Motor protection • Phase Loss, Reversal or Sequence
Motors - Single Phasing • Phase Unbalance
Gensets - correct engine • System Under Voltage
rotation
All portable equipment
All rotating machines

Introduction
This Crompton Protector is designed to An unbalanced supply voltage can lead to
comprehensively monitor the three phase temperature rises in motors. An unbalance
supply. It monitors the correct phase rotation voltage as little as 10% can increase
or sequence of three phase supply systems. operating temperature to150% of normal.
Rotating machines are particularly vulnerable
For permanent installations, this relay should
to incorrect phase sequence. Three phase
be used to monitor the incoming supply,
motors can rotate in the wrong direction,
protecting all equipment against incorrect
potentially leading to physical damage or the
We also manufacture front of connection at initial installation or after
risk of injury to personnel, yet voltage and
panel mounting phase maintenance work. Rotating machines that
current readings may appear normal. If one
sequence indicators cannot tolerate reverse rotation or pose
phase is lost because of a blown fuse,
significant risk to personnel under this
electric motors can continue to operate
condition should be individually protected with
(single phasing) which can result in severe
this relay. The possibility of incorrect supply
electrical or mechanical damage.
connection is much more likely in portable
This relay has the added advantage that it will equipment or marine applications.
detect the phantom or regenerated phase
that can be caused by a single phase failure
on some equipment or when running motors
at low load levels.

Product Function
The protector continuously monitors the three The setpoint control allows adjustment of the
phase supply. With the correct phase voltage matching between 5% and 15%.
sequence applied and all three voltages are
The time delay function operates only for the
balanced within the required limits, the front
voltage unbalance condition. The delay can be
panel LED will illuminate and the output relay
used to prevent nuisance tripping due to
will be energized. An incorrect sequence,
short term unbalance situations. Incorrect
missing phase, out of balance or under
phase rotation, a missing phase or an under
voltage condition will de-energize the relay,
voltage condition trip the relay immediately.
and the LED will be extinguished.

Protection against:
• Incorrect phase sequence • Unbalanced voltage
• Loss of one phase • A phantom or regenerated phase voltage
• Under voltage

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Phase Balance

Specification
Approvals: U.L. recognised Set Points:
CSA approved up to 480V. Unbalance: Adjustable 5% to 15%

System: 3 phase, 3 or 4 wire Time Delay: Up to 10 seconds adjustable

Frequency: 50 or
60Hz Under Voltage (Type 252-PSG only):
Internally preset at 15% of
Nominal Voltage: 100, 110, 120, 208, 277, nominal voltage (other values
220, 230, 240, 380,400, between 10% and 30%
415, 440 & 480V available on request)
(not operative if voltage falls
Burden: 3VA approx. below 70% of the nominal
Voltage Withstand: 1.2 x continuously voltage or set point on type
1.5 x for 10 x 10 seconds 252-PSG)

Product Code Examples

Relay Input Protection ANSI No. Catalogue No.

3 Phase 3 or 4 Wire 120V L-L 60Hz Phase loss & unbalance 47 252-PSFU-PQBX-C6
480V L-L 60Hz Phase loss & unbalance 47 252-PSFU-SEBX-C6
120V L-L 60Hz Phase loss, unbalance, under voltage 47/27 252-PSGU-PQBX-C6-T1-IA
480V L-L 60Hz Phase loss, unbalance, under voltage 47/27 252-PSGU-SEBX-C6-T1-IA

Connection Diagrams
252-PSF
252-PSG Relay
Contact Set 1 Contact Set 2

Note: No neutral connection is required

Input

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Reverse Power (Current)

Application:
Generator Set protection -
for detecting loss of the
prime mover (engine) and
preventing motoring
Feeder protection - to
detect reverse power
under fault conditions The Crompton Reverse Power Protector On site adjustment of the trip point and
provides continuous surveillance for A.C. time delay ensures accurate protection
generators operating in parallel or for against ‘motoring’ in the event of engine
boosting mains supplies. failure and prevents tripping from surges
during synchronising.

Introduction
The Crompton reverse power Protectors As soon as the reverse power level increases
provides continuous surveillance of a.c. above the setpoint limit, the time delay is
generators against motoring. activated, after which a trip will occur. The
time delay prevents the relay from tripping for
Reverse power relays are used to detect the
a predetermined period to prevent nuisance
failure of the prime mover (engine) when
tripping.
active energy (Watts) flows into the generator
causing rotation - the set will operate like an The products also feature an internal
electric motor, which can cause significant differential (hysteresis) setting of 1% to
mechanical damage. This relay offers an reduce nuisance tripping if the measured
adjustable reverse power setpoint between signal is noisy or unstable.
2% and 20% of nominal power, and time
These units are powered from the measuring
delay adjustment range of 0 to 20 seconds.
supply.

Product Function
The protector relay approximates the power The reverse power level will trip as expected
level in the system by measuring current and at the calibrated point for unity power factor,
power factor, but does not actually measure however, the system power factor does effect
the system voltage. When the reverse power the trip point calibration. The relay becomes
level exceeds the setpoint, the time delay is more sensitive at lagging power factors, as
started. When the time has elapsed, the relay almost all systems exhibit inductance. At
will energize and the red LED will illuminate to leading power factors, this relay is less
indicate the trip condition. The relay will sensitive.
automatically reset once the power level falls
below the setpoint minus the differential, the
LED will extinguish and the relay de-energizes.
The time delay is not active when resetting.

Product customisation options

Please contact the factory.
• Adjustment ranges - different adjustment • Relay operation - standard models are fail
ranges are possible for the setpoint and safe, but the relays can be customised to
time delay controls de-energise on trip

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Reverse Power (Current)

Setting up Instructions
The “% set” potentiometer trimmer on the front current lead connections and, with forward
label is calibrated as a percentage of the input power, measuring the trip point value on a
current rating e.g. of 5A, and not of the forward suitable ammeter (reconnect leads on
kW. completion).

Adjust the “% set” trimmer to the required Adjust the ‘Delay’ to the required time delay.
tripping value, 7.5% to 10% is normal. Setting 10 seconds is normally adequate.
accuracy can be checked by reversing the

Specification
Approvals: U.L. recognized up to 300V. Burden: 2VA maximum
CSA approved up to 240V.
Frequency: 50 or 60 or 400Hz on request
Nominal Voltage: 100, 110, 120, 220, 230,
240, 277, 380, 400, 415, Setpoint Adjustments: Reverse power 2-20%
440 or 480V Delay adjusstment: Time delay: 0/20 seconds
Overload: 1.2 x continuously Repeatability: 0.5%
1.5 x for 10 x 10 seconds
Hysteresis: 1%
Burden: 3VA maximum
Monitoring Range:
Nominal Current: 5A Power Factor: 0.5 inductive/unity/
or 2, 3, 4, 6, 8 & 10A 0.2 capacitive
Overload: 2 x continuously Current: 20% - 100% of nominal input
10 x for 3 seconds

Product Code Examples

Relay Input Protection ANSI No. Catalogue No.

Single Phase or 3ph 4W 5A, 120V, 60Hz Reverse Power 2-20% 32 256-PASU-LSBX-PQ-C6-EA
3 Phase 3 Wire 5A, 120V, 60Hz Reverse Power 2-20% 32 256-PATU-LSBX-PQ-C6-EA
Single Phase or 3Ph 4W Push to Test 5A, 120V, 60Hz Reverse Power 2-20% 32 256-PAQU-LSBX-PQ-C6-EA
3 Phase 3 Wire Push to Test 5A, 120V, 60Hz Reverse Power 2-20% 32 256-PARU-LSBX-PQ-C6-EA

Connection Diagram
256-PAS
256-PAT
256-PAQ Input Volts
Single phase
256-PAR 3 phase 4 wire
3 phase 3 wire

Contact Set 1 Contact Set 2

Input Amps
Output Relay

Note: Only one CT connection is required.

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Synchro - Check (Paralleling)

Protection ensures
Frequency matching
Voltage matching
Phase angle matching

The Crompton Synchro check relay can The volt-free relay contacts change state
Application be used to assist in the semi-automatic when the voltage level, phase relationship
paralleling of two ac power systems. and frequency are within the selected
Co-generation
synchronising limits.
Generator sets
Gen-Bus synchronising
Introduction
Bus-Bus synchronising
As part of a manual control system, the ensure the two systems are suitably matched
Assists in manual operator will make adjustments the Voltage before the breaker can close.
synchronising (excitation) and frequency (engine speed)
Connecting two electrical systems that are
Monitors auto using a synchroscope or lamps, and will then
not closely matched can cause expensive
attempt to manually close the breaker. This
synchronising systems damage and disturbance to the electrical
synch check protector will qualify that the two
system. Using this relay will ensure that
systems are closely matched before
damage will not occur.
permitting the breaker to close.
As part of an automatic synchronising
arrangement, this relay can be used as an
independent backup or checking device to
We also manufacture front of
panel mounting electro-
mechanical or electronic
synchroscopes, and synchro Product Function - 256-PLL
check relays
The relay continuously monitors the Voltage, The relay contacts can be used in the main
phase displacement and frequency of two breaker circuit to disable a close command
supplies. A single setpoint adjustment until both gensets are within acceptable
permits selection of suitable matching, and a limits.
red LED illuminates when the relay is
Operating power is taken from the generator
energized, indicating that the two supplies are
supply.
well matched - OK to close the breaker.

Additional Feature - 256-PLD

This version operates as explained above, but generator can be connected without
includes a dead bus detection function. synchronizing, to ensure continuity of supply.
The absence of bus voltage will cause the
If there is a requirement for a continuous
relay to energize.
supply or emergency power, then the

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Synchro - Check (Paralleling)

Specification
Approvals: U.L. recognized up to 300V. Setpoint Synchronising:
Nominal Voltage: 100, 110, 120, 208, 220, Set point: 10% to 30% of the nominal
230, 240, 277, 380, 400, voltage
415, 440 & 480V Adjustment: (6° to 20° electrical)
Voltage tolerance: -25% to +30% of the nominal Weight: Approximately 0.85kg
voltage Output Relay:
Frequency: 45 or 50 or 55 or 60 or 65Hz Relay contacts: 1 pair NO*, 1 pair NC*
Burden maximum: Bus 2VA, Generator 4VA *2 pair NO and 2 pair NC available on request.

Product Code Examples

Relay Input Protection ANSI No. Catalogue No.

Single Phase or 3 Phase 120V, 60Hz Phase Angle & Voltage 25 Live bus 256-PLLU-PQBX-C6
3 or 4 Wire 120V, 60Hz 25 Dead Bus 256-PLDU-PQBX-C6

Connection Diagrams
256-PLL
256-PLD

Generator Busbar
System Connections Connections
1 2 3 4
3 phase 4 wire L1 N L1 N
3 phase 3 wire L1 L2 L1 L2
1 phase 2 wire L1 N L1 N

Normally Normally
Open Closed
Contacts Contacts

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
D.C. Voltage

The Crompton D.C. voltage Protectors

provide continuous surveillance of the
monitored circuit. When the measured
voltage moves outside the set-point limits,
Features the relay will operate after the selected
time delay or differential, giving an alarm
Adjustable setpoint and/or initiation signal. The protectors can
protect for:
Adjustable time delay
• Under voltage
Internal differential
• Over voltage
LED trip indication
• Battery level control
2 pole relay contacts
• No external power

Introduction
Crompton D.C. Voltage Protectors provide The time delay prevents the relay from
continuous surveillance of the monitored tripping for a predetermined period to prevent
voltage circuit, typically a battery supply or nuisance tripping.
Application: charging circuit. These products offer user
The products also feature an internal
adjustable trip point (setpoint) and time delay
differential (hysteresis) setting of 1% to
Battery Supplies - to settings. The time delay setting adjustment
reduce nuisance tripping if the measured
monitor correct terminal range is typically 0 to 10 seconds, although
signal is noisy or unstable.
longer delays are available.
voltage and detect under
The units draw their operating power from the
or over voltage conditions As soon as the monitored signal moves
measuring inputs
outside of the setpoint limit, the time delay is
Battery Chargers - to activated, after which a trip will occur.
monitor charging voltage
is correct

Product Function
Over voltage models: When the monitored Under voltage models: When the monitored
voltage exceeds the setpoint, the time delay voltage falls below the setpoint, the time
is started. When the time has elapsed, the delay is started. When the time has elapsed,
relay will energize and the red LED will the relay will de-energize and the red LED will
illuminate to indicate the trip condition. The extinguish to indicate the trip condition. The
relay will automatically reset once the relay will automatically reset once the
monitored voltage falls below the setpoint monitored voltage rises above the setpoint
minus the differential. When reset, the LED plus the differential. When reset, the LED will
will extinguish and the relay de-energizes. The illuminate and the relay energizes. The time
time delay is not active when resetting. delay is not active when resetting.

Product customisation options

Please contact the factory.
• Adjustment ranges - different adjustment • Relay operation - standard models are fail
ranges are possible for the setpoint and safe, but the relays can be customised to
time delay controls energise or de-energise on trip
• Differential - Internally fixed value between
1% and 15%

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
D.C. Voltage

Specification
Model 252-PDU, 253-PDC Model 252-PDE
D.C Voltage: minimum 18 to maximum 20V D.C. D.C. Voltage: minimum 18 to maximum 20V D.C.
minimum 20 to maximum 32V D.C. minimum 20 to maximum 32V D.C.
Time Delay: Externally adjustable, specify either: Time Delay: Optional preset up to 30 seconds
0-10 seconds, 0-20 seconds, (specify) 10 seconds standard)
0-30 seconds, 0-40 seconds, Differential: Externally adjustable range
0-100 seconds 1-15%
Differential: Preset to 1% All models:
(Any value between 1 and 15%)
Burden: <3VA
Overload: 1.2 x continuously Setpoint
Repeatability: Better than 0.5%

Product Code Examples

Frequency Relay D.C. Input Protection ANSI No. Catalogue No.

D.C. relay 18-20V Under Voltage External time delay 27 252-PDUU-NABX-T1-EB

D.C. relay 18-20V Under Voltage Differential 27 252-PDEU-NABX-EB
D.C. relay 24V Over and Under Voltage (2 output relays) 27/59 253-PDCU-BDBX-T1-EC-BD
D.C. relay 18-20V Over Voltage External time delay 27 252-PDOU-NABX-T1-EB

Connection Diagrams
252-PDU
252-PDE
Relay
Contact Set 1 Contact Set 2

Input

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Thermistor Trip
The Crompton thermistor trip relay
continuously monitors the working
temperature inside equipment.
When the temperature exceeds a safe
limit, the relay can be used to shunt
equipment down until it has cooled down
Application again. The protector can be used to
protect:
The Crompton Thermistor Trip
• Motors
Relay, when used in
conjunction with positive • Transformers
temperature co-efficient • Generators
thermistors, will give full
protection against: Introduction

Sustained overload Many motors and transformers are supplied with Thermistors are low cost over-temperature
thermistor temperature sensors already fitted. sensors.
Single phasing
Product Function
Locked rotor
The protector operates by de-energizing a Any number of thermistors may be used in
Blocked ventilation
relay when the thermistors detect a critical series connection providing the resistance at
High ambient temperature temperature condition. An illuminated green normal working temperature is less than
LED indicates when the temperature is within 1500 ohms.
normal working limits. There are no user adjustments on this relay.

Product Code Examples

Relay Input A.C. Aux Power Reset ANSI No. Catalogue No.

P.T.C. Thermistors 1500 Ohms 120V 49 Manual. 252-PMMU-STBX-DG

1500 Ohms 120V 49 Auto. 252-PMTU-STBX-DG

Specification
Approvals: This model is U.L. recognized Reset: Model 252-PMT: Automatically resets
Model 252 - PMMU is CSA approved. when temperature returns to normal
Input: Positive temperature coefficient Model 252-PMM: fitting a link between
thermistors (series connected 1500Ω terminals R1 and R2 will latch the
maximum at normal temperature) product in its tripped state when an over
Range: Trip 2500-3500Ω temperature condition is detected. The
Reset 1500-2300Ω relay can be reset by pressing the front
panel reset switch, opening the R1 - R2
Status: Normally energized - green LED
link, or interrupting the auxiliary supply.
illuminated. Relay is de-energized above
trip point Auxiliary Supply:
A.C. 50/60Hz 110, 120, 220, 230 & 240V ±20%
Burden: 2VA approx.

Connection Diagrams
252-PMT 252-PMM
Output Relay Output Relay
Contact Set 1 Contact Set 2 Contact Set 1 Contact Set 2

Thermistor Thermistor
Supply Connections Supply Connections

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Hot Spot 3

Protection against
Ineffective cooling
Blocked ventilation
Overloads
Worn bearings
Loss of one phase
Under voltage
Unbalanced voltage
The Crompton Hot Spot 3 relay accepts The relay can be used to protect:
up to three inputs from resistance • Electric motor windings
temperature detectors (RTD) and
• Transformers
provides up to three user adjustable trip
points which can be used to initiate • Generator windings
Application alarms, cooling systems or shutdown. • Bearing temperature

Motor protection
Transformer protection
Introduction
Gensets protection
This Crompton Hot Spot Protector monitors poor ventilation, shorted turns, insulation
Heating equipment three temperature zones. RTD temperature breakdown, single phasing etc.
sensors are often fitted inside electric motors
This product offers up to three user
to detect hot spots in the windings or the
adjustable setpoints and relay contacts.
bearings. RTD sensors are popular because
These can be used to raise alarms, switch on
they offer a good accuracy for a reasonable
cooling systems or shut down the effected
price. The same sensors can be used inside
equipment.
transformers, generator sets, gas turbines or
Select an analog or digital as part of a process control system. The product features a 1mA analog output
indicator from our range. signal for remote temperature indication.
Hot spots can be caused by many conditions,
such as overloads, over voltage, unbalanced
supply, worn bearings, ineffective cooling,

Product Function
The protector continuously monitors the three will de-energize, and a red LED illuminated to
RTD temperature sensors. The highest indicate the trip condition. When the
temperature is indicated with a yellow LED, temperature drops below the setpoint, the
and can be accurately measured or displayed relay will reset to the energized condition, and
using the 0/1mA analog output signal. The the LED will extinguish.
temperature is compared with the user
Three product models offer one, two or three
adjustable setpoints. When the measured
adjustable setpoints.
temperature exceeds the setpoint, the relay

Information Required
When ordering please supply the following information:
• The type of temperature sensor being used, e.g. Platinum PT100
• The maximum temperature or meter scale, e.g. 100% = 1mA = 150°C
• The setpoint adjustment range, e.g. 0°C to 150°C.

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Hot Spot 3

Specification
Approvals: U.L. recognized Rating:
Input: Up to 3 inputs, 2 or 3 wire A.C: 240V, 5A non-inductive
RTD sensors either 10Ω D.C: 24V,5A resistive
Copper or 100Ω Platinum Operations: 0.2 million at the above loads
minimum span 100°C
Reset: Automatic
Auxiliary Supply: A.C 50/60Hz, 110, 120, 220,
Standard: de-energize at set point with
230 & 240V ±20% (specify)
rising temperature
D.C. - contact factory
Indicator O/P: 1mA into 0/4kΩ load
Output Relay(s):
Burden: 4VA maximum
Relay differential: Standard 2% of range
Type: SP changeover

Product Code Examples

Relay Protection ANSI No. A.C. Aux power Catalogue No.

3 RTD inputs 3 trip points 49 120V 256-PRAU-R*-BX-DG-RO-LI

3 RTD inputs 2 trip points 49 120V 256-PRBU-R*-BX-DG-RO-LI
3 RTD inputs 1 trip point 49 120V 256-PRCU-R*-BX-DG-RO-LI
Optional indicating instrument •077-05KA-FA
• (specify scale) R * Specify type and temperature range

Connection Diagrams
256-PRA
256-PRB
256-PRC
Indication

Remote L.E.D.'s
R.T.D. Inputs if required

Output Relays Aux. Supply

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Hot Spot 6

Protection against
Ineffective cooling
Blocked ventilation
Overloads
Worn bearings
Loss of one phase
Under voltage
The Crompton Hot Spot 6 is a The relay can be used to protect:
Unbalanced voltage temperature trip relay accepting up to six • Electric motor windings
inputs from resistance temperature
• Transformers
detector (RTD) elements and provides
one user adjustable trip point which can • Generator windings
be used to initiate alarms, cooling or • Bearing temperature
shutdown when the monitored
temperature exceeds the set limit.

Application Introduction
This Crompton Hot Spot Protector monitors Hot spots can be caused by many conditions,
Motor protection
six temperature zones. RTD temperature such as overloads, over voltage, unbalanced
Transformer protection sensors are often fitted inside electric motors supply, worn bearings, ineffective cooling,
to detect hot spots in the windings or the poor ventilation, shorted turns, insulation
Gensets protection bearings. RTD sensors are popular because breakdown, single phasing etc.
they offer a good accuracy for a reasonable
Heating equipment This product monitors six sensors and offers
price. The same sensors can be used inside
a user adjustable setpoint and relay contacts.
transformers, generator sets, gas turbines or
This can be used to raise alarms, switch on
as part of a process control system.
cooling systems or shut down the effected
equipment.

Product Function
The protector continuously monitors the six will de-energize, and a red LED illuminated to
RTD temperature sensors. The highest of the indicate the trip condition. When the
six temperatures is indicated with a red LED. temperature drops below the setpoint, the
This temperature is compared with the user relay will reset to the energized condition, and
adjustable setpoint. When the measured a green LED will illuminate to indicate 'Safe'.
temperature exceeds the setpoint, the relay

Information Required
When ordering please supply the following informaton:
• The type of temperature sensor being used, e.g. Platinum PT100
• The setpoint adjustment range, e.g. 0°C to 150°C.

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Hot Spot 6

Specification
Approvals: U.L. recognized Reset: Automatic. Relay differential
Input: Up to six RTD sensors e.g. (pull-in to drop-out) 4°C
100Ω platinum (PT100) or nominal
10Ω copper Auxiliary Supply: a.c. 50/60Hz, 110, 120, 220,
Ambient Temperature: 0 to 60°C 230 & 240V ±20% (specify)
Trip Point Range of Adjustment: Burden: 6VA maximum
100°C (e.g. 50 to 150°C, 100 Output Relay:
to 200°C etc)
User Adjustment: Screwdriver adjustable, multi- Type: Single pole changeover
turn potentiometer, access on Rating:
front panel. Approximately 5°C A.C: 240V, 5A non-inductive
per turn. Turn anti-clockwise to D.C: 24V, 5A resistive
raise trip point. Operations: 0.2 million at the above loads
Operating Time: <100ms Reset: Automatic
Repeatability: Within 1°C

Product Code Example

Relay Protection ANSI No. Catalogue No.

6 RTD inputs Preset trip point 80-180 degree C 49 256-PCCU-R*BX-DG-AS

R * Specify type and temperature range

Connection Diagrams
256-PCC

When used for less than 6 RTD

inputs the unused terminals 1, 2 & 3
must be linked together.

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
D.C. Millivolts/Thermocouple

The Crompton millivolt protectors accept

Application using current inputs from current shunts or
shunts thermocouples, and the user adjustable
trip can be set to initiate an alarm when
Use with current shunts to the input exceeds the desired level.
monitor battery charging
currents
Monitor current drain
Under/over current
Introduction
Application using thermo-
Crompton millivolt Protectors provide As soon as the monitored signal moves
couples continuous surveillance of high DC currents outside of the setpoint limit, the time delay is
when used with current shunts, or can be activated, after which a trip will occur. The
Under/over temperature used to monitor temperatures using time delay prevents the relay from tripping for
Detect hotspots thermocouples. All industry standard shunts a predetermined period to prevent nuisance
are supported, and all popular therocouples tripping.
are supported. The relays offers user
The products also feature an internal
adjustable trip point (setpoint) and time delay
differential (hysteresis) setting of 1% to
settings. The time delay setting adjustment
reduce nuisance tripping if the measured
range is typically 0 to 10 seconds, although
signal is noisy or unstable.
longer delays are available.
These units require an auxiliary power supply.

Product Function
'Over' models: When the monitored signal 'Under' models: When the monitored signal
Use these protector relays with exceeds the setpoint, the time delay is falls below the setpoint, the time delay is
our Current Shunts. started. When the time has elapsed, the relay started. When the time has elapsed, the relay
will energize and the red LED will illuminate to will de-energize and the red LED will
indicate the trip condition. The relay will extinguish to indicate the trip condition.
automatically reset once the monitored signal The relay will automatically reset once the
falls below the setpoint minus the differential. monitored signal rises above the setpoint
When reset, the LED will extinguish and the plus the differential. When reset, the LED will
relay de-energizes. illuminate and the relay energizes. The time
The time delay is not active when resetting. delay is not active when resetting.

Product customisation options

Please contact the factory.
• Adjustment ranges - different adjustment • Relay operation - standard models are fail
ranges are possible for the setpoint and safe, but the relays can be customised to
time delay controls energise or de-energise on trip
• Differential - Internally fixed value between
1% and 15%

Information Required
When ordering please supply the following information:
• The rated shunt output, eg. 75mV
• The auxiliary supply voltage.
• The type of thermocouple, eg. Type K.
• The nominal operating temperature, e.g. 150°C

Protector Relays
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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
D.C. Millivolts/Thermocouple

Specification
Approvals: U.L. recognized Input Impedance: Approximately 50kΩ
D.C. Millivolts models are CSA Source Impedance: Maximum 100Ω
approved Setpoint Repeatability: 0.5% of span
Input d.c. millivolts: Spans 10mV (minimum), Hysteresis: 2% of span
50mV, 60mV, 75mv, 100mV,
Adjustment: Low trip 0-80%
150mV.
High trip 40-120%
Thermocouple: Types J, K, R, S, T
Time Delay: Up to 10 seconds adjustable
Minimum Span 10mV
Maximum Span 50mV Auxiliary Supply:
Thermocouple Break Protection (TBP): A.C. 50/60Hz 120V or 240V (±20%)
Upscale drive is standard D.C. voltage: 12V or 24V (±20%)
Cold Junction Compensation (CJC): Burden: 3VA maximum
Available on application Voltage Withstand: 1.2 x continuously
Overload: 10 x continuously 1.5 x for 10 x 10seconds to
B.S. 6253

Product Code Examples

Relay Input Protection ANSI No. A.C. Aux Power Catalogue No.

D.C. Millivolt 50mV High trip 74 120V 252-PBTU-ECBX-DG-T1-EA

D.C. Millivolt 50mV Low trip 74 120V 252-PBSU-ECBX-DG-T1-EB
D.C. Millivolt 100mV High trip 74 120V 252-PBTU-GBBX-DG-T1-EA
100mV Low trip 74 120V 252-PBSU-GBBX-DG-T1-EB
Thermocouple Type J, K, R, S, T High trip 49 120V 252-PTOU-T*BX-DG-T1-EA
Type J, K, R, S, T Low trip 49 120V 252-PTUU-T*-BX-DG-T1-EB
T * Specify type and temperature range

Connection Diagrams
252-PBT
252-PBS Relay
252-PTU Contact Set 1 Contact Set 2
252-PTO

252-PBT

Monitored Supply
Value

Protector Relays
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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
D.C. Transducer

Application The Crompton D.C. transducer protector

accepts standard process signals and
Forward/Reverse Watts monitors that these are inside the set limits.
Under/Over Watts
Forward/Reverse VAr
Under/Over VAr
Under/Over VA
Power Factor Monitoring
and Control
Introduction
Crompton transducer Protectors provide As soon as the monitored signal moves
continuous surveillance of the DC process outside of the setpoint limit, the time delay is
voltage or current signal. Combining the activated, after which a trip will occur. The
protection relay with a measuring transducer time delay prevents the relay from tripping for
can form specialised control products when a predetermined period to prevent nuisance
ever self contained relays are not available. tripping.
The relay offers user adjustable trip point
The products also feature an internal
(setpoint) and time delay settings. The time
differential (hysteresis) setting of 1% to
delay setting adjustment range is typically 0
reduce nuisance tripping if the measured
to 10 seconds, although longer delays are
signal is noisy or unstable.
available.
Use these protector relays with These units require an auxiliary power supply.
our Paladin transducers.

Product Function
'Over' models: When the monitored signal 'Under' models: When the monitored signal
exceeds the setpoint, the time delay is falls below the setpoint, the time delay is
started. When the time has elapsed, the relay started. When the time has elapsed, the relay
will energize and the red LED will illuminate to will de-energize and the red LED will
indicate the trip condition. The relay will extinguish to indicate the trip condition.
automatically reset once the monitored signal The relay will automatically reset once the
falls below the setpoint minus the differential. monitored signal rises above the setpoint
When reset, the LED will extinguish and the plus the differential. When reset, the LED will
relay de-energizes. illuminate and the relay energizes. The time
The time delay is not active when resetting. delay is not active when resetting.

Product customisation options

Please contact the factory.
• Adjustment ranges - different adjustment • Relay operation - standard models are fail
ranges are possible for the setpoint and safe, but the relays can be customised to
time delay controls energise or de-energise on trip
• Differential - Internally fixed value between
1% and 15%

Protector Relays
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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
D.C. Transducer

Specification
Approvals: U.L. recognized Setpoint Repeatability: 0.5% of span
CSA Approved. Hysteresis: 2% preset
(up to 24V D.C.) Adjustment: Low trip 0-80%
Input: High trip: 40-120%
Current D.C.: 0-1, 0-5, 0-10, 0-20, 4-20mA Time Delay: Up to 10 seconds adjustable
Volt drop 1V Auxiliary Supply:
Voltage D.C.: 1V to 50V, input resistance A.C. 50/60Hz: 120V or 240V±20%
10kΩ/V
Burden: 3VA maximum
Voltage Withstand: 1.2 x continuous
1.5 x for 10 x 10s

Product Code Examples

Relay Input Protection ANSI No. A.C. Aux Power Catalogue No.

Transducer 1mA Low trip (falling signal) 0-80% 74 120V 252-PBAU-FABX-DG-T1-EB

1mA High trip (rising signal) 40-120% 74 120V 252-PBBU-FABX-DG-T1-EA
1mA Low & High (2 output relays) 74 120V 253-PBVU-FABX-DG-T1-EC
Transducer 4/20mA Low trip (falling signal) 0-80% 74 120V 252-PBAU-HGBX-DG-T1-EB
4/20mA High trip (rising signal) 40-120% 74 120V 252-PBBU-HGBX-DG-T1-EA
4/20mA Low & High (2 output relays) 74 120V 253-PBVU-HGBX-DG-T1-EC
Transducer 10V Low trip (falling signal) 0-80% 74 120V 252-PBAU-MTBX-DG-T1-EB
10V High trip (rising signal) 40-120% 74 120V 252-PBBU-MTBX-DG-T1-EA
10V Low & High (2 output relays) 74 120V 253-PBVU-MTBX-DG-T1-EC

Connection Diagrams
252-PBB 253-PBV
252-PBA

Relay
Contact Set 1 Contact Set 2 Monitored Under Relay Over Relay
Value Contact Set 1 Contact Set 1

Under Relay Supply Over Relay

Monitored Supply Contact Set 2 Contact Set 2
Value

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Speed Sensing

Protect against
Open circuit sensor
detection - a break in the The Crompton speed sensing relay
sensor lead will de- monitors rotating equipment and
energise the over-speed provides three output contacts which
relay can be used to initiate alarm or
Zero reset cranking - the shutdown signals. The relay also
crank relay will only reset provides a tachometer output for
when the input frequency speed indication.
falls below 20% of the
crank set point
Under speed alarm or load
shedding
Over speed alarm or Introduction
shutdown
The Crompton speed sensing protector The product also offers an analog output that
monitors the speed of rotation using a low can be used to monitor or display the speed.
cost magnetic pickup. Speed sensors are
The product operates from the 12V or 24V dc
often used in generator set engines, gas
battery supply, and speed is measured and
turbines, motors, gear boxes or any rotating
Applications machines.
calculated from the number of sensor pulses
per revolution. Since the sensor is magnetic,
Engine monitoring The relay will detect under speed, over speed and rotating steel component can be used,
and stopped conditions, and the setpoint such as the flywheel which has gear teeth.
Generator set protection relays can be used to raise an alarm or shut This will result in a large number of pulses
down the equipment. There are three per revolution, and lead to greater accuracy.
Gas turbine monitoring
setpoint adjustments and relay contacts.
Monitor the engine
governer
Product Function
The protector continuously monitors the Under speed relay - will detect when the
rotations speed, and updates the analog normal running speed has been achieved.
Select an analog or digital output signal. An output of 0.75 mA indicates This can be used to enable the generator's
normal speed (100%) while 1mA indicates electrical protection. It can also be used to
speed indicator from our range.
133% of nominal speed. The calibration point trigger load shedding. A red LED illuminates
can easily be user adjusted. when an under speed condition exists.
Three setpoint control adjustments allow Over speed relay - will detect a stuck throttle
setting of the desired speed limits for or overshoot, and can be used to shut down
cranking, under speed and over speed. the engine. A red LED indicates over speed
trip.
Cranking relay - will detect if the the engine
is running or stopped. This relay can be used Fail safe operation - the relay will detect an
to ensure the cranking motor is disconnected open circuit speed sensor, and de-energize
once the engine has started running. Set the the overspeed relay.
cranking setpoint just above the cranking
motor speed. A red LED illuminates when the
relay is energized, indicating a trip condition.

Information Required
When ordering please supply the following information:
• The number of pulses per revolution, e.g. flywheel teeth = 30
• The nominal running speed, e.g. 3600 RPM.
• The DC battery supply, e.g. 24 Vdc

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Speed Sensing

Application
The Protector Speed Sensing Relay provides SP1 - disengages the crank starter
three user adjustable trip levels with LED relay
SP2 - energizes protection or under-speed alarm
state indication and a speed indicator output
signal. The trip functions provided are: SP3 - alarms or trips on overspeed

Specification
Approvals: U.L. recognized Repeatability: 0.5% of span
Input: Hysteresis: 2% (SP2, SP3) SP1 resets at
Pulse: 5V-75V peak to peak 20% of setting
Frequency: 0-1kHz minimum range Auxiliary Supply:
0-10kHz maximum range D.C. voltage: 12V or 24V (±20%)
(speed of rotation r.p.m. x Burden: 3VA
number of teeth ÷60) Output:
Open circuit protection: Overspeed relay de-energizes Calibration Signal: 0-1mA into 0-1,000 ohms
Setpoints: Calibration value: 0.75mA = 100%
Setpoint SP1 (crank): 10%-50% 1mA = 133% of nominal
Setpoint SP2 (under): 50%-100% speed
Setpoint SP3 (over): 100%-130%

Product Code Examples

Relay Protection ANSI No. A.C. Aux power Catalogue No.

5V to 75V peak to peak 3 trip points 12/14 12V 253-PH3U-BGBX-FS-V2

(specify rev/min and flywheel teeth number) (specify SP1, SP2, SP3) 12/14 24V 253-PH3U-BGBX-FS-V4

Accessories

Magnetic Speed Sensor, STD length 1.125", thread 5⁄8-18 UNF CMS3010AN
Magnetic Speed sensor, long reach 4.00" thread 5⁄8-18 UNF CM3010AN40
Mating Output connector & clamp - 2 pin (*4) or 3 pin (*3) Specify * CMS3106-10SL-*S

Connection Diagrams
253-PH3

CRANK UNDER OVER

Internal link fitted between 8 and 5

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 Protector Trip Relays
250 Series DIN Rail and Wall Mounted -
Dimensions

DIN Rail and Wall Mounted

Model 252
2 HOLES
Ø 4.1
55 (2.2) 112 (4.4)
55 (2.2)

(0.5)
12
35 (1.37)
35 (1.37)
70 (2.8)

15.5
(0.6)
17.5 (0.68)
35 (1.37)

RELEASE CLIP

Model 253

75 (2.9) 112.5 (4.4) 60 (2.4)

60 (2.36)
50 (1.96)
35 (1.37)

70 (2.8)

RELEASE CLIP 2 FIXING HOLE 'A' 2 FIXING HOLE 'A'

TO SUIT M4 TO SUIT M4

Model 256
150 (5.9) 112.5 (4.4)
35 (1.37)

70 (2.8)

RELEASE CLIP
135 (5.3)
50 (1.96)
60 (2.36)

2 FIXING HOLE 'A' 2 FIXING HOLE 'A'

TO SUIT M4 TO SUIT M4

Protector Relays
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