Siemens 7UT51

7UT51 v3
Transformer Differential Protection (87T and 87HS)
4
PRIM-2330C 63
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
-
event occurs when
restraint conditions end or the 87T/87HS function drops out or
resets (see Sections 4.6 and 4.7).
87Blk HarmPhA
87Blk HarmPhB
87Blk HarmPhC
5641
5642
5643
C
C
C
G
G
G
S
S
S
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 1617) runs out, or the
87T/87HS function detects that an internal fault is also occurring
(see Section 4.5 on page 58).
87Blk SatPhA
87Blk SatPhB
87Blk SatPhC
5651
5652
5653
C
C
C
G
G
G
S
S
S
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).
87Diff GenTrip 5671 C S T
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
-
trip time delay (if there is one) has
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.
87Diff TripPhA
87Diff TripPhB
87Diff TripPhC
87 Trip
5672
5673
5674
5691
C
C
C
C
S
S
S
S
T
T
T
T
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
-
trip time delay (if there is one) has
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.
87HS Trip 5692 C S T
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.
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
Transformer Differential Protection (87T and/or 87HS)
Occurrence
LCD Abbreviation Event Oper Fault In/Out