Date Code 20001006
Breaker Monitor, Metering, and Load Profile Functions
8-19
SEL-351 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 = /OUT2 + ...
In this example, output contact OUT2 is set to close:
OUT2 = CLOSE
(CLOSE is the logic output of Figure 6.1)
Anytime output contact OUT2 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 = /OUT2 + ...) 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.
Summary of Contents for SEL-351
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