Sel 551 - Figure 3.17 Voltage Relay (27;59) Provides Reclose Block Signal to SEL-551

3.32
SEL-551 Relay Instruction Manual Date Code 20110408
Relay Elements and Logic
Reclosing Relay
Additional Settings Example
If the relay is used on a feeder with a cogenerator, it is desirable that the
reclosing does not take place into a line energized by an islanded generator. A
potential transformer and voltage relay are installed on the line side of the
circuit breaker, and a contact from the undervoltage relay is connected to input
IN2 of the SEL-551.
Figure 3.17 Voltage Relay (27/59) Provides Reclose Block Signal to SEL-551
The contact from the voltage relay indicates the presence or absence of
voltage. If line voltage is present, open interval timing is stalled. If line voltage
is not present, open interval timing proceeds. This is realized with the
following setting:
79STL = IN2
or
79STL = !IN2
depending on the nature of the contact from the voltage relay.
Other Settings Considerations
If no special skip shot or stall open interval timing conditions are desired,
make the following settings:
79SKP = 0 (numeral 0)
79STL = 0 (numeral 0)
Block Reset Timing
(79BRS)
The block reset timing setting 79BRS keeps the reset timer from timing.
Depending on the reclosing relay state, the reset timer can be loaded with
either reset time:
79RSD (Reset Time from Reclose Cycle)
or
79RSLD (Reset Time from Lockout)
Depending on how setting 79BRS is set, none, one, or both of these reset
times can be controlled. If the reset timer is timing and then 79BRS asserts to:
79BRS = logical 1
reset timing is stopped and will not start timing again until 79BRS deasserts
to:
79BRS = logical 0
27/59
(+)
(-)
SEL-551
IN2
27/59
Generator
52
SEL-551