Siemens 7UT51 User Manual

5
Motor or Generator Differential Protection (87M/G)
7UT51 v3
76 PRIM-2330C
Table 5.1
Events Related to Differential Protection of a Motor or Generator (87M/G)
Time Delay Before Trip
If an 87M/G pickup occurs, the corresponding
time
-
delay
-
before
-
trip timer will start (see Section 5.7 on page 75).
This event will not occur if the time delay setting is zero. Outputs
marshalled to this event will remain actuated until the time delay
expires (Address 1725).
87Diff Pickup 5621 C S T
Restraint
If the motion of the operating point suggests that a high
-
current
fault outside the protected zone is saturating the CTs, the event is
reported for each phase. The corresponding going
-
event occurs
when the duration timer (Address 1717) runs out, or the 87M/G
function detects that an internal fault is also occurring (see
Section 5.5 on page 74).
87Blk SatPhA
87Blk SatPhB
87Blk SatPhC
5651
5652
5653
C
C
C
G
G
G
S
S
S
Trip and Reset
Any 87M/G trip event will also cause event 5671 to occur. With the
default marshalling, event 5671 will actuate all the trip contacts,
signal contact 2, and (as for the general trip of any protection
function) signal contact 1. Outputs actuated by 87M/G trip events
will remain actuated until the 87M/G function resets (the same
conditions for dropout, event 5631G), plus the additional reset time
(Address 1727).
87Diff GenTrip 5671 S T
The 87M/G function will trip if and when ALL the following are true:
• an 87M/G pickup has occurred, and it has not yet dropped out
or already caused a trip,
• the 87M/G time
-
before
-
trip time delay (if one is set
Address 1725) has expired,
• any restraint has ended,
There are separate 87M/G trip events for each phase, and one
(event 5691) that reports the 87M/G trip of any phase. With the
default marshalling, event 5691 will light and latch LED 2 and (as
for any protection function trip event) LED 1.
87Diff TripPhA
87Diff TripPhB
87Diff TripPhC
87 Trip
5672
5673
5674
5691
C
S
S
S
S
T
T
T
T
If an 87M/G trip event occurs, the values of the differential currents
and restraining currents for each phase at the time of the trip are
recorded in the then open fault log.
Diff Ia=
value
Diff Ib= value
Diff Ic= value
Rest Ia= value
Rest Ib= value
Rest Ic= value
5701
5702
5703
5704
5705
5706
C
C
C
C
C
C
Configuration Events
If the motor/generator
-
description settings are changed, the
current
-
matching factors for the phase currents are recalculated
and reported.
k CT 1=
factor
k CT 2= factor
5713
5714
C
C
Motor or Generator Differential Protection (87M/G) Occurrence LCD Abbreviation Event Oper Fault In/Out

Siemens 7UT51 Specifications

General

Brand	Siemens
Model	7UT51
Category	Relays
Language	English