Differential Voltage
Uploaded by
Belkacem KADIDifferential Voltage
Uploaded by
Belkacem KADIPVD
Differential Voltage
High speed differential protection for
busses and feeders for use with
standard bushing-type current
Features and Benefits Protection and Control
■ Replacement for earlier PVD models ■ High-speed, high z voltage sensing
■ Thyrite stacks limit potential voltage across ■ High seismic instantaneous O/C unit
relay ■ Breaker failure protection
■ Drawout case construction (with suitable timing relay)
Applications
■ Bus differential high z voltage
■ Shunt reactor differential protection
■ Transformer high z ground differential
GE Multilin 1
PVD Differential Voltage
Introduction unit 87L, and/or to implement same ratio. When adding to an
breaker failure protection when existing bus, at least one CT set
The PVD21 relay is a single- used with a suitable timing relay in the new breaker should be
phase, high-speed, and other auxiliary devices. ordered with the same ratio as
high-impedance, voltage-operat- the bus differential CT’s in the
ed relay designed to provide The PVD21A and 21B models use
a single Thyrite® stack to limit the existing breakers. If the differen-
protection in bus differential tial circuit unavoidably includes
schemes. The PVD21 utilizes the magnitude of the voltage devel-
oped across the relay. For different ratio CT’s, application of
same operating principle (high the PVD21 may still be possible,
impedance voltage) as the earlier applications where high internal
fault currents can be encoun- but special attention must be
PVD models, but provides faster given to protection against over-
operating speeds and higher seis- tered, the PVD21C and 21D
models are available. These voltage conditions during internal
mic capabilities. Typical operating faults. Refer applications involv-
speed is 20 ms at 4X pickup (See relays include two Thyrite stacks,
and offer the same basic protec- ing different ratio CT’s to the local
Fig. 1). The PVD21 is mechanically General Electric Company sales
interchangeable with the earlier tion, but with a slight decrease in
sensiti vity. See the PVD21 office.
PVD21 models, and provides
additional output contacts as instruction book for proper selec-
shown in Figs. 2 and 3. tion and application for the
PVD21C and 21D models.
Description
Current Transformer
The PVD21 relay is available in
four models. All models include a Requirements
high-speed voltage sensing unit The PVD21 relays can be applied
(87L) that operates from the volt- for bus protection in most cases
age provided by the differentially where CT’s having negligible
connected CT’s during an internal leakage reactance are used. This
fault. In addition, a high seismic generally includes any kind of
instantaneous overcurrent unit current transformer with a
(87H) is included in the PVD21B toroidal core if the windings (on
and 21D models The overcurrent the taps used) are completely
unit 87H, which has an electrically distributed about the core. It is
separate output contact, may be preferable that all the CT’s in the
used to supplement the voltage bus differential circuit have the
Connection Diagram
Fig. 2. Simplified internal connection diagram for PVD21A and PVD21C Fig. 3. Simplified internal connection diagram for PVD21B and PVD21D
87L 87L = Voltage-operated unit
S.I. = Seal-in unit
* = Short finger Used with
PVD21D
87L = Voltage-operated unit
87H = Overcurrent unit
87L S.I. = Seal-in unit
S.I. Used with Input to 87L * = Short finger
PVD21C circuitry 87H
S.I. 87L S.I. Input to 87L
circuitry
S.I. 87L 87H
* * * * * * * * * * * *
1 3 5 7 9
1 3 5 7 2 4 6 8 10
2 6 8 Shorting bar
Shorting bar
2 www.GEindustrial.com/Multilin
PVD Differential Voltage
Ratings
The voltage unit 87L has a contin-
uous rating of 150 V.
The current unit 87H is a Hi-G,
high seismic instantaneous unit
with the following ratings for the
coil:
87H UNIT (2-50 A RANGE)
Continuous One Sec
Link Range Rating Rating
Position (A) (A) (A)
Low 2-10 3.7
130
High 10-50 7.5
The contacts of the 87L unit have
a current closing rating of 30 A
for voltages not exceeding 250 V.
The current carrying rating is
limited by the seal-in unit rating
(see below). The target and seal-
in unit is a Hi-G, high seismic 5
unit, dual rated with 0.2 and 2.0 A
(dc) taps, with the following
ratings:
Tap Setting
Description
0.2 A 2.0 A
DC resistance (Ohms) 8.0 0.24
Minimum operating (A) 0.2 2.0
Carry continuous (A) 0.3 3
Carry 30 A for (sec) 0.03 4
Carry 10 A for (sec) 0.25 30
Fig. 1. Typical operating times of the PVD
relay—87L unit
30
Order online –
save time
Pickup time in
milliseconds
20
10
www.GEindustrial.com/pm
0
0 2 3 4 5 6
Multilples of pickup setting
SELECTION GUIDE
Single-phase (3 Required)
Continuous Frequency Voltage Unit Current Unit Approx. Wt.
Rating (87L) (87H) Thyrite® Model Case in lbs (kg)
(Hz) Stacks Number Size
(V) Min Max Min Max Net Ship
}
60 --- --- PVD21A1A
50 --- --- A2A
1
60 2A 50A PVD21B1A
50 2A 50A B2A
}
150 60 75V 500V --- --- PVD21C1A M1 20(9) 27( 1 2.2)
50 --- --- C2A
2
60 2A 50A PVD21D1A
50 2A 50A D2A
60 4A 100A 2 PVD21D3A
NOTE: All PVD relays include a 0.2/2.0 A T. & SI Unit used in conjunction with the 87L Unit.
www.GEindustrial.com/Multilin 3