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1 GETTING STARTED
The B90 requires minimal maintenance after it is commissioned into service. Since the B90 is a microprocessor-based
relay, its characteristics do not change over time. As such, no further functional tests are required.
The B90 performs a number of continual self-tests and takes the necessary action in case of any major errors (see the
Relay Self-tests section in chapter 7). However, it is recommended that B90 maintenance be scheduled with other system
maintenance. This maintenance can involve in-service, out-of-service, or unscheduled maintenance.
In-service maintenance:
1.
Visual verification of the analog values integrity, such as voltage and current (in comparison to other devices on the
corresponding system).
2.
Visual verification of active alarms, relay display messages, and LED indications.
3.
LED test.
4.
Visual inspection for any damage, corrosion, dust, or loose wires.
5.
Event recorder file download with further events analysis.
Out-of-service maintenance:
1.
Check wiring connections for firmness.
2.
Analog values (currents, voltages, RTDs, analog inputs) injection test and metering accuracy verification. Calibrated
test equipment is required.
3.
Protection elements setting verification (analog values injection or visual verification of setting file entries against relay
settings schedule).
4.
Contact inputs and outputs verification. This test can be conducted by direct change of state forcing or as part of the
system functional testing.
5.
Visual inspection for any damage, corrosion, or dust.
6.
Event recorder file download with further events analysis.
7.
LED Test and pushbutton continuity check.
Unscheduled maintenance, such as a disturbance causing system interruption:
1.
View the event recorder and oscillography or fault report for correct operation of inputs, outputs, and elements.
If it is concluded that the relay or one of its modules is of concern, contact GE Multilin for service.
GE Multilin
B90 Low Impedance Bus Differential System
1.5 USING THE RELAY
1.5.7 COMMISSIONING
1-19
1
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