Schweitzer Engineering SEL-387-0, Instruction Manual

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6.5
Date Code 20170601 Instruction Manual SEL-387-0, -5, -6 Relay
Setting the Relay
Additional Relay Settings
In our example, inputs IN101 to IN103 are assigned to represent the 52a contacts.
That is, 52A1 = IN101, 52A2 = IN102, and 52A3 = IN103. (Note again that
inputs appear on the right side of an equation, outputs on the left side.) 52A4
is not used, and is set to zero. The connections for the 52a inputs are shown in
Figure 2.9 .
The four Close variables CL1 through CL4 are set up to define the conditions
under which a closing can take place. In our example, these are set up to
respond to a
CLOSE n command from a communications port, or an external
contact input from a SCADA RTU or other switch. Specifically, CL1 = CC1+
/IN104, CL2 = CC2 + /IN105, and CL3 = CC3 + /IN106, where “/” denotes
detection of a “rising edge” for the input shown. CL4 is not used, and is set to
zero. Within these SEL
OGIC
control equations, inputs IN104 to IN106 have been
defined as being related to the close initiation function for the specific
breakers. The CL
n variable initiates the close logic, resulting in Relay Word
bit CLS n being set to one, unless the logic is disabled by an unlatch condition,
discussed below. Note that connections for the closing function are not shown
in
Figure 2.9 .
Closing can now take place, but only if an output contact has been assigned to
this function. Returning to the Output Contact Logic setting area for our
example, we set OUT105 = CLS1, OUT106 = CLS2, and OUT107 = CLS3.
These contacts must be wired to the closing circuits of the individual breakers.
In the Close Logic setting area, four variables remain. ULCL1 to ULCL4
define the conditions for unlatching the close logic. These are set in our
example to be the presence of any trip logic output. That is, ULCL1 = TRIP1
+ TRIP4, ULCL2 = TRIP2 + TRIP4, and ULCL3 = TRIP3 + TRIP4. ULCL4
is not used and is set to zero. ULCL
n will remove the seal-in of the close logic
and return Relay Word bit CLSn to zero. A closed 52a contact or a Close
Failure Detection will also unlatch the Close Logic. The output contact that
follows the CLS
n bit will open in response.
The Trip Logic and Close Logic settings can be set differently in the six
setting groups. See
Section 4: Control Logic for more information on Trip and
Close Logic.
There are two additional miscellaneous timer settings that apply to the Trip
and Close Logic. These are TDURD and CFD. TDURD is the minimum trip
duration time and defines the minimum length of time the trip signal will be
issued, regardless of other inputs to the Trip Logic. The default setting is
9 cycles. The CFD, or Close Failure Detection time delay, is an overriding
timer to unlatch the close logic if the breaker has not yet closed. The default
setting is 60 cycles.
Event Report
Triggering (ER) and
Length Selection
(LER, PRE)
There are three settings for Event Reports: (1) ER, (2) LER, and (3) PRE.
The first, ER, defines in a SEL
OGIC
control equation the conditions under
which a report will be generated. In our example, ER = /50P11 + /51P1 + /
51Q1 + /51P2 + /51Q2 + /51P3. Events will be generated from the pickup of
the various overcurrent elements, whether they fully time out or not. This will
yield reports for some external faults that do not result in tripping of the
transformer breakers, but for which information might be useful. Winding 3
element pickup is used to detect external tertiary circuit faults that may be too
weak to be detected by the Winding 1 elements. Also, since tertiary circuits
normally are short, probably only including the substation buses and auxiliary
equipment, reports on faults of any kind would be of great interest.