Schweitzer Engineering Laboratories SEL-351-7 - Station DC Battery Voltage Dips Anytime; Station DC Battery Voltage Dips During Circuit Breaker Closing; Operation of Station DC Battery Monitor When AC Voltage Is Powering the Relay

Date Code 20020426 Breaker Monitor, Metering, and Load Profile Functions 8-19
SEL-351-5, -6, -7 Instruction Manual
Station DC Battery Voltage Dips During Circuit Breaker Closing
To generate an event report when the SEL-351 Relay closes the circuit breaker, make the
SEL
OGIC control equation event report generation setting:
ER = /OUT102 + ...
In this example, output contact OUT102 is set to close:
OUT102 = CLOSE (CLOSE is the logic output of Figure 6.1)
Anytime output contact OUT102 closes and energizes the circuit breaker close coil, any dip in
station dc battery voltage can be observed in column Vdc in the event report.
This event report generation setting (ER = /OUT102 + ...) might be made just as a testing setting.
Generate several event reports when doing circuit breaker close testing and observe the
“signature” of the station dc battery voltage in column Vdc in the event reports.
Station DC Battery Voltage Dips Anytime
To generate an event report anytime there is a station dc battery voltage dip, set the dc voltage
element directly in the SEL
OGIC control equation event report generation setting:
ER = \SV4T + ...
Timer output SV4T is an example dc voltage element from the bottom of Figure 8.10. Anytime
dc voltage falls below pickup DCHIP, timer output SV4T drops out (logical 1 to logical 0
transition), creating a falling-edge condition that generates an event report.
Also, the Sequential Event Recorder (SER) report can be used to time-tag station dc battery
voltage dips [see Sequential Events Recorder (SER) Report in Section 12: Standard Event
Reports, Sag/Swell/Interruption Report, and SER].
Operation of Station DC Battery Monitor When AC Voltage is Powering the Relay
If the SEL-351 Relay has a 125/250 Vac/Vdc supply, it can be powered by ac voltage (85 to
264 Vac) connected to the rear-panel terminals labeled POWER. When powering the relay with
ac voltage, the dc voltage elements in Figure 8.9 see the average
of the sampled ac voltage
powering the relay—which is very near zero volts (as displayed in column Vdc in event reports).
Thus, pickup settings DCLOP and DCHIP should be set off (DCLOP = OFF, DCHIP = OFF)—
they are of no real use.
If a “raw” event report is displayed (with the EVE R command), column Vdc will display the
sampled ac voltage waveform, rather than the average.