Siemens 7UT51

4
Transformer Differential Protection (87T and 87HS)
7UT51 v3
62 PRIM-2330C
4.10 Events and Actions
Figure 4.13 shows the logic of these events.
Table 4.3 describes the events that control and are
generated by the 87T/87HS function. They are listed
in the order that they are likely to occur, which is
roughly in numerical order by their event identification
number (shown in the “Event” column). The text in the
“LCD Abbreviation” column is the corresponding text
that will appear when viewing logs on the front panel
LCD display. In the “Oper” column, a letter “C” or “G”
indicates that the “Coming” and/or “Going” events are
logged in the Operational Log, while if in the “Fault”
column they indicate that the events are logged in the
open fault log. A letter in the “In/Out” column indicates
that the event can be controlled by a binary-signal
input (“I”), control an LED and/or signal contact (“S”),
and/or control a trip contact (“T”).
Transformer Differential Protection (87T and/or 87HS)
Occurrence
LCD Abbreviation Event Oper Fault In/Out
Change in Operational Status
When the operational status of the 87T/87HS function changes,
a going
-
event for the old status occurs followed by a
coming
-
event for the new status. The normal operational status
is set in Address 1601.
87Diff OFF
87Diff BLOCK
87Diff ACTIVE
5615
5616
5617
C
C
C
G
G
G
S
S
S
A binary input can temporarily change the operational status of
the function (see Section 13.2 on page 126). Any outputs
marshalled to these events will remain actuated for as long as
the binary input remains actuated.
>87Diff BLOCK
>87DiffBlkTrip
5603
5605
I
I
S
S
Pickup and Dropout
If the operating point of any phase rises above 85% of the height
of the pickup characteristic, or if the restraint current (I
rest
)
exceeds four times rated nominal current (I
n
), the 87T/87HS
function will pickup (event 5631C). If no fault log is already
open, a new one will open.
If the operating point for all phases remains below 70% of the
height of the pickup characteristic for two full cycles, the 87T/
87HS function will dropout (event 5631G). See Section 4.4 on
page 55.
87Diff GenFlt 5631 C G S T
An 87T phase
-
pickup occurs if the operating point of a phase
rises above the pickup characteristic. Outputs marshalled to
these events will remain actuated until dropout of the
corresponding phase.
87Diff PhA
87Diff PhB
87Diff PhC
5681
5682
5683
C
C
C
S
S
S
An 87HS pickup occurs if the operating point of a phase rises
above the 87HS threshold level. Outputs marshalled to these
events will remain actuated until dropout of the corresponding
phase.
87HS PhA
87HS PhB
87HS PhC
5684
5685
5686
C
C
C
S
S
S
Time Delay Before Trip
If an 87T or 87HS pickup occurs, the corresponding
time
-
delay
-
before
-
trip timer will start (see Section 4.9 on
page 61). These events will not occur if the corresponding time
delay setting is zero. Outputs marshalled to these events will
remain actuated until the corresponding time delay expires.
87Diff Pickup
87Diff HS PU
5621
5622
C
C
S
S
T
T