Siemens 7UT51 Instruction Manual page 63

7UT51 v3
Transformer Differential Protection (87T and/or 87HS)
Occurrence
Restraint
If the 87T/87HS function is in pickup, harmonic restraint
conditions (inrush and/or overexcitation) are reported separately
for each phase. If crossblocking is in effect, all three events
occur in parallel. The corresponding going
restraint conditions end or the 87T/87HS function drops out or
resets (see Sections 4.6 and 4.7).
If the motion of the operating point suggests that a high
fault outside the protected zone is saturating the CTs, the event
is reported for each phase. The corresponding going
occurs when the duration timer (Address 1617) runs out, or the
87T/87HS function detects that an internal fault is also occurring
(see Section 4.5 on page 58).
Trip and Reset
Any 87T or 87HS 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 87T/
87HS trip events will remain actuated until the 87T/87HS
function resets (the same conditions for dropout, event 5631G),
plus the additional reset time (Address 1627).
The 87T function will trip if and when ALL the following are true:
• an 87T pickup has occurred, and it has not yet dropped out
or already caused a trip,
- -
• the 87T time before
expired,
• any restraint has ended,
There are separate 87T trip events for each phase, and one
(event 5691) that reports the 87T 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.
The 87HS function will trip if and when ALL the following are
true:
• an 87HS pickup has occurred, and it has not yet dropped out
or already caused a trip,
-
• the 87HS time before
expired,
(Note that restraint has no effect on the 87HS function.)
Event 5692 reports the 87HS trip of any phase. With the default
marshalling, it will light and latch LED 3 and (as for any
protection function trip event) LED 1.
If an 87T or 87HS 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.
PRIM-2330C
-
event occurs when
trip time delay (if there is one) has
-
trip time delay (if there is one) has
Transformer Differential Protection (87T and 87HS)
LCD Abbreviation
87Blk HarmPhA
87Blk HarmPhB
87Blk HarmPhC
-
current 87Blk SatPhA
87Blk SatPhB
87Blk SatPhC
-
event
87Diff GenTrip
87Diff TripPhA
87Diff TripPhB
87Diff TripPhC
87 Trip
87HS Trip
Diff Ia= value
Diff Ib= value
Diff Ic= value
Rest Ia= value
Rest Ib= value
Rest Ic= value
Event Oper Fault
5641 C G
5642
C G
5643
C G
5651 C G
5652
C G
5653
C G
5671 C
5672 C
5673
C
5674
C
5691
C
5692 C
5701 C
5702
C
5703
C
5704
C
5705
C
5706
C
4
In/Out
S
S
S
S
S
S
S T
S T
S T
S T
S T
S T
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