PCS-978
Transformer Protection
The PCS-978 numerical protection system can provide
full-scheme protection and control in one rack for various
transformer applications, including two-winding transformers,
three-winding transformers and auto-transformers. It also
can be used to protect shunt reactors. Up to 36 analog input
channels including current and voltage inputs are provided.
The extensive functional library, programmable logic and
configurable I/O are integrated to meet flexible applications.
Functions The unique current differential protection includes the
unrestraint current differential element, percentage restraint
Protection and Control current differential element and DPFC differential element.
• Transformer restrained current differential protection. (87PT)
Three slopes are provided for the restraint characteristic of The PCS-978 reserves two sets of CT input for dual-breaker
percentage current differential protection. It also integrates protection in one-and-a-half breaker and ring breaker
the inrush current blocking, CT saturation discrimination, arrangements. To enhance the accuracy of data sampling,
over excitation blocking, CT ratio compensation and unique the frequency-tracking function is used to trace the real-time
vector group compensations. current/voltage value.
• Unrestrained current differential protection. (87UT)
The unrestraint current differential protection instantaneously
Biased current differential protection consists of CT
responds and clears a serious fault immediately.
saturation and harmonic blocking elements
• DPFC baised current differential protection. (87DT)
• Reactor DPFC biased current differenital protection.
Deviation of Power Frequency Component (DPFC)
(7/87DR)
differential current protection is sensitive to turn-to-turn fault
DPFC biased current differential protection is regardless of
and high resistance fault and is immune to load current.
the load current and is sensitive to small internal fault current
within the reactor.
• Reactor restraint current differential protection. (87R)
Inrush current can be distinguished to avoid maloperation of
• Restricted Earth Fault Protection. (REF)
current differential protection by detecting harmonic
Zero sequence differential protection is used as REF for
each Wye-connection winding to detect sensitive ground
• Reactor unrestrained current differential protection.
fault. Up to 3 REF protections are provided.
(50/87UR)
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• Winding differential protection. (87W/87N) • Phase overcurrent alarm element. (50PAlm)
Winding differential protection has high sensitivity to internal The output could be used for the initiation of cooling system
earth faults. Up to 3 winding differential protections are and this element is not supervised by General Fault Detector
provided. element.
• Inter-turn fault protection. (32G/21G) • Phase-to-phase impedance protection for HV and MV side.
Inter-turn protection consists of zero-sequence power (21P)
directional element and zero-sequence impedance element. Users have options to select the forward direction or
backward direction by logic setting, and power swing
• Overexciation protection. (24) blocking logic is integrated to improve the safe operation.
Overexcitation protection based on the ratio of voltage and
frequency is provided. • Phase-to-ground impedance protection for HV and MV side.
(21G)
Users have options to select the forward direction or
• Underfrequency and overfrequency protection. (81U/81O)
backward direction by logic setting, and power swing
Under frequency protection with df/dt blocking and over
blocking logic is integrated to improve safe operation.
frequency protection are both provided. The frequency is
derived from positive-sequence voltage.
• Power swing blocking. (68)
The unique power swing blocking logic is integrated to
• Mechanical protection. (MR)
improve the safe operation of impedance protection.
Under frequency protection with df/dt blocking and over
frequency protection are both provided. The frequency
• Voltage and current drift auto adjustment.
is derived from positive-sequence voltage. Up to eight
The relay continually and automatically traces the voltage
channels of mechanical protection are provided for tank.
and current drifts and adjusts the zero point to the normal
value.
• Four stage phase overcurrent protection (50P/51P/67P)
Overcurrent protection can be supervised by voltage
• Frequency tracking.
element, harmonic element and directional element. IDMT
Frequency tracking is provided to accommodate the
curves complied with IEC and ANSI are provided for
frequency shift in power system.
selection. Up to four overcurrent protections are provided.
• Four stage zero sequence overcurrent protection for each Monitoring and Metering
side. (50N/51N/67N) • CT saturation detection.
Overcurrent protection can be supervised by voltage
• Inrush current detection.
element, harmonic element and directional element. IDMT
curves complied with IEC and ANSI are provided for • Overexcitation detection.
selection. Up to four zero-sequence overcurrent protections • Harmonic blocking function.
are provided. • CT failure detection supervision.
• VT failure detection supervision.
• Two-stage residual overvoltage protection. (59G)
IDMT curves complied with IEC and ANSI are provided for • Tripping circuit supervision.
selection. • Self diagnostic.
• Fault Recorder.
• Two-stage definite-time and inverse-time phase overvoltage
protection. (59P)
IDMT curves complied with IEC and ANSI are provided for Communications
selection. • Two 10Base-T/100Base-TX (RJ45) ports and two optional
100Base-FX ports with IEC 61850-8-1 MMS and GOOSE for
• Four-stage undervoltage protection. (27) non-time-critical message, IEC 60870-5-103 over TCP/IP or
Rate-of-change of voltage is provided for the blocking. DNP 3.0
• Two RS-485 rear ports with IEC 60870-5-103
• Thermal overload protection. (49)
Thermal overload protection based on fundamental current • Six or Eight 100Base-FX ports with IEC 61850-9-2 Sampling
or harmonic current is provided for tripping and alarm. Value and GOOSE for time-critical message
• One RS-485 rear port for clock synchronization
• Breaker failure protection. (50BF) • One RS-232 rear port for printer
Breaker failure protection for each breaker is supplied to
• One faceplate RJ45 port for testing and setting
initiate re-tripping and adjacent breaker tripping.
• Clock synchronization via Pulse-Per-Second, IRIG-B and
• Pole disagreement protection. (62PD) SNTP
External binary input and zero-sequence/negative-sequence
current are used to detect the pole disagreement state of the
circuit breaker.
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Features
• CT transient detection element based on the ratio of • The restraint current differential protection with initial restraint
zero-sequence current to positive-sequence current is slope consists of sensitive and conventional differential
provided for REF to eliminate the influence of CT transient elements as well as independent CT saturation criterion.
characteristic difference.
• Maximum 4 group CT and 1 neutral CT inputs for REF
• The PCS-978 provides RTD input module and DC mA input protection are provided.
module to detect the oil-temperature.
• The CT saturation detection function based on 2nd and 3rd
• Maximum six groups of CT inputs for differential protection harmonics is adopted to avoid maloperation.
are provided.
• The amplitude of residual voltage is compensated to ensure
• 24 vector groups are available for the application to two- that the zero-sequence power directional element can
winding transformer. distinguish the direction correctly when system impedance is
too small.
• 288 vector groups are available for the application to
3-winding transformer. • Voltage for overexcitation protection calculation is the RMS
value of three phase voltages which is not affected by
• Optional inrush current distinguished principle is provided:
frequency fluctuation.
harmonic criterion (second harmonic and third harmonic) or
waveform distortion. • Directional element can be selected to control each stage
phase overcurrent protection with three options: none
• There are two optional modes for harmonic criterion:
direction, forward direction and reverse direction.
self-adaptive blocking mode and phase-to-phase cross
blocking mode. Self-adaptive blocking mode can prevent • Disturbance records are composed of 64 fault reports and
maloperation during transformer energization effectively and 64 disturbance waveforms. The file format of waveform
ensure high speed for internal faults under normal operation. is compatible with international COMTRADE91 and
COMTRADE99 file. Up to 80 analog inputs and 200 binary
• Fifth harmonic or third harmonic criterion applied to detect
inputs can be recorded, and three oscillograph triggering
overexciation condition.
mode are supported.
• The Δ→Y vector group compensation is used to adjust
• The relay is compatible with IEC 61850-8-1 MMS, GOOSE
the phase angle of secondary current and the inrush
and IEC 61850-9-2 Sampling Value and provides the
current feature is reserved in each phase to realize phase-
independent interfaces for station bus and process bus
segregated inrush current restraint for percentage differential
respectively.
protection.
• The DPFC restraint current differential protection is immune
to load current but sensitive to small internal fault current
within the transformer.
Technical data
Power Supply
Standard IEC 60255-11:2008
Voltage Range 88 to 300 Vdc or 88 to 264 Vac
Permissible AC ripple voltage ≤15% of the nominal auxiliary voltage
<30W (for conventional substation application)
Quiescent condition
<35W (for smart substation application)
Burden
<35W (for conventional substation application)
Operating condition
<40W (for smart substation application)
Analog Current
Standard IEC 60255-27:2005
Phase rotation ABC
Nominal frequency (fn) 50Hz, 60Hz
Nominal range fn±5Hz
Rated Current (In) 1A 5A
Linear to 0.05In ~ 40In
continuously 4In
for 10s 30In
Thermal withstand capability
for 1s 200In
for half a cycle 250In
Burden <0.2VA/phase < 0.25VA/phase
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Analog Voltage
Standard IEC 60255-6, IEC60288
Phase rotation ABC
Nominal frequency (fn) 50Hz, 60Hz
Nominal range fn±5Hz
Rated phase-to-phase voltage (Un) 100~130V 200V (Broken delta for residual voltage)
linear to 1~170V 1~233V
continuously 200V 220V
Thermal withstand capability 10s 260V 380V
1s 300V 420V
Burden < 0.20VA/phase @Un < 0.8VA/phase@Un
Transducer Input
Standard IEC 60255-1:2009
Input range 0-20mA 0-10V 0-250V
Input resistance 235Ω 8.8kΩ 248kΩ
Accuracy 0.5 class 0.5 class 0.5 class
Binary Inputs
Standard IEC 60255-1:2009
Rated voltage 24V 30V 48V 110V 125V 220V 250V
Rated current 1.2mA 1.5mA 2.4mA 1.1mA 1.25mA 2.2mA 2.5mA
Pickup voltage 13V~17V 17V~21V 26V~34V 60.5V~77V 60.5V~77V 121V~154V 121V~154V
Dropout voltage 90% of pickup voltage
Maximum permissive voltage 300Vdc
Withstand 2000VAC, 2800VDC(continuously)
Resolving time for logic input <1ms
Binary Outputs
Item Tripping contact Signal contact
Output mode Potential free contact
5A@250V AC 8A@380V AC
Continuous carry
5A@250V DC 8A@250V DC
Pickup time <8ms <10ms
Drop-off time <5ms (not include delay time by software) <8ms
6A@3s 10A@3s
Short duration current 15A@0.5s 20A@0.5s
30A@0.1s 30A@0.2s
0.6A@48VDC 0.7A@48VDC
Breaking capacity (L/R=40ms) 0.2A@110VDC 0.3A@110VDC
0.1A@220VDC 0.2A@220VDC
380V AC 380V AC
Maximal working voltage
250V DC 250V DC
Test voltage across open contact 1000V RMS for 1minute 1200V RMS for 1 minute
Mechanical Specifications
Enclosure dimensions (W×H×D) 482.6mm×177.0mm×291.0mm
Mounting Flush mounted
Trepanning dimensions (W×H) 450.0mm×179.0mm, M6 screw
Housing color Silver grey
Protection class: IEC 60255-1:2009
Front side IP40, up to IP51 (Flush mounted)
Other sides IP30
Rear side, connection terminals IP20
Pollution degree 2
Ambient Temperature and Humidity Range
Standard IEC 60255-1:2009
Operating temperature -40°C to +70°C Note: The operating temperature of LCD is -20°C ~ +70°C
Transport and storage temperature range -40°C ~ +70°C
Permissible humidity 5% ~ 95%, condensation not permissible
Altitude <3000m
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Communication Port
- EIA-485 Port
Baud rate 4.8kbit/s, 9.6kbit/s, 19.2kbit/s, 38.4kbit/s, 57.6kbit/s, 115.2kbit/s
Protocol IEC 60870-5-103:1997
Maximal capacity 32
Transmission distance <500m
Safety level Isolation to ELV level
Twisted pair Screened twisted pair cable
- Ethernet Port
Connector type RJ-45
Transmission rate 100Mbits/s
Transmission standard 10Base-T/100Base-TX
Transmission distance <100m
Protocol IEC 60870-5-103:1997 or IEC 61850
Safety level Isolation to ELV level
- Optical Fiber Port
Characteristic Plastic optical fiber Glass optical fiber
Terminal BFOC/2.5 (OR F-SMA) BFOC/2.5 (OR F-SMA)
Fibre size Step-index 980/1000 μm Graded-index 62.5/125 μm
Transmission distance Up to 40m Up to 1000m
Wave length 660nm 820nm~860nm
Temperature range -5°C ~+55°C -5°C ~+55°C
Minimum receiving power Min. -20dBm Min. -24dBm
System reserve Min +3dB Min +3dB
- Print Port
Type RS-232
Baud Rate 4.8kbit/s, 9.6kbit/s, 19.2kbit/s, 38.4kbit/s, 57.6kbit/s, 115.2kbit/s
Printer type EPSON® 300K printer
Safety level Isolation to ELV level
- Clock Synchronization Port
Type RS-485
Transmission distance <500m
Maximal capacity 32
Timing standard PPS, IRIG-B
Safety level Isolation to ELV level
Type test
- Environmental tests
Dry cold test Per IEC60068-2-1:2007
Dry heat test Per IEC60068-2-2:2007
Damp heat test, cyclic Per IEC60068-2-30:2005
- Mechanical tests
Vibration Per IEC 60255-21-1:1988 Class I
Shock and bump Per IEC 60255-21-2:1988 Class I
- Electrical tests
Standard IEC 60255-27:2005
Dielectric tests Test voltage 2kV, 50Hz, 1min
Standard IEC 60255-5:2000
Impulse voltage tests Test voltage 5kV
Overvoltage category III
Insulation resistance measurements Isolation resistance >100MΩ@500VDC
- Electromagnetic Compatibility
Per IEC 60255-22-1:2007
1MHz burst disturbance test Common mode: class III 2.5kV
Differential mode: class III 1.0kV
Per IEC60255-22-2:2008 class IV
Electrostatic discharge test For contact discharge: 8kV
For air discharge: 15kV
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Per IEC 60255-22-3:2007 class III
Frequency sweep
Radiated amplitude-modulated
10V/m (rms), f=80…1000MHz
Radio frequency interference tests Spot frequency
Radiated amplitude-modulated
10V/m (rms), f=80MHz/160MHz/450MHz/900MHz
Radiated pulse-modulated
10V/m (rms), f=900MHz
Per IEC 60255-22-4:2008
Fast transient disturbance tests Power supply, I/O, Earth: class IV, 4kV, 2.5kHz, 5/50ns
Communication terminals: class IV, 2kV, 5kHz, 5/50ns
Per IEC 60255-22-5:2008
Power supply, AC input, I/O port: class IV, 1.2/50us
Surge immunity test Common mode: 4kV
Differential mode: 2kV
Per IEC 60255-22-6:2001
Conducted RF Electromagnetic Disturbance
Power supply, AC, I/O, Comm. Terminal: Class III, 10Vrms, 150 kHz~80MHz
Per IEC 61000-4-8:2001
Power Frequency Magnetic Field Immunity
class V, 100A/m for 1min, 1000A/m for 3s
Per IEC 61000-4-9:2001
Pulse Magnetic Field Immunity
class V, 6.4/16μs, 1000A/m for 3s
IEC 61000-4-10:2001
Damped oscillatory magnetic field immunity
class V, 100kHz & 1MHz–100A/m
IEC60255-11: 2008
Auxiliary power supply performance Voltage dips: Up to 300ms for dips to 40% of rated voltage without reset
Voltage short interruptions: 100ms for interruption without rebooting
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