Schweitzer Engineering Laboratories SEL-221F, Instruction Manual

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Enables from Setting Procedure
Select torque control for 51N
51NTC
Select torque control of 67N
67NTC
Remote-End-Open Perm. Trip Enable REJOE
Loss-of-potential enable
LOPE
Intermediate Logic
The logic equations developed below represent combinations of the relay elements and other
conditions. In the following equations,
"
*
"
indicates a logical
"
and,
"
while
"
+
"
indicates a
logical
"
or.
"
Loss-of-Potential (LOP) Logic
Set LOP
Clear LOP
= 47QL * NOT (46QL)
Set LOP includes a three-cycle pickup
delay.
+ NOT (47P) * NOT ( 50P
)
=
NOT (47QL) *
47P
The different set and clear conditions ensure that LOP stays latched during subsequent faults,
but is cleared when balanced voltages return. Loss of three-phase potentials due to potential
fuse operation may cause the relay to trip if phase current is above the 50P setting.
You determine how the relay uses loss-of-potential detection by selecting the LOPE setting.
The LOPE setting choices and their associated results are:
N Rlay sets LOP bit when loss-of-potential condition is detected.
Distance and directional elements are not blocked.
Set the LOP bit in a programmable logic mask to indicate condition, if desired.
Y
Relay sets LOP bit when loss-of-potential condition is detected.
Distance elements are blocked and directional elements default forward.
Set the LOP bit in a programmable logic mask to indicate condition, if desired.
1 Relay blocks distance elements and directional elements default forward when
LOP condition is detected.
If the 52A input is asserted while LOP is detected, the Relay Word LOP bit is
asserted.
If the 52A input is not asserted while LOP is detected, the Relay Word LOP bit
is not asserted.
Set the LOP bit in a programmable logic mask to indicate that a loss-of-poten-
tial has occurred while the breaker is closed, if desired.
2 Relay sets LOP bit when loss-of-potential condition is detected.
Distance elements are blocked and directional elements default forward.
Relay asserts ALARM contact to indicate the LOP condition.
2-16 Specifïcations
SEL-221F, -1 Instruction Manual
Date Code 920817