ABB RELION REX640 Operation Manual page 156

Maintenance and Periodical Testing
humidity near to the maximum specified for the product, or it can be due to dust,
salt, chemicals, or other corrosive agents.
Infrequent operations
If the relay has performed very few operations during the observation period, which
is typical for spare feeders, we recommend applying the three years periodical
testing interval. The long inoperative time is not typically a problem for the relay, if
the auxiliary power is turned on continuously, but it might be more problematic for
the circuit breaker operation mechanism.
Frequent operations
When the relay performs several operations during the observation period, specially
initiated by the protection functions, and the relay's performance during the faults
are analyzed we recommend applying the five years periodical testing interval. The
analyzing can be based on relay's events, fault records and disturbance records.
Utilization of relay's external and internal supervision features
REX640 contains several supervision features, both for relay's internal functionality
and for relay's external circuitry. For external circuitry there are many supervision
features. Whether the features are activated depends on the relay configuration and
settings. It's highly recommended to take an advantage of these features, since
they will cover a large part of the complete protection circuitry offering continuous
supervision. The following features are included:
• Trip (and close) coil supervision
• Circuit breaker condition monitoring
• Motor operated disconnector supervision
• Current transformer secondary circuit supervision
• Fuse failure supervision
• Protection (point-to-point) communication supervision
• Station communication supervision
When in use and configured correctly, these supervision features will activate events
and alarms, both on local HMI and on remote systems.
The protection relay's self-supervision function monitors the relay's performance
and indicates possible problems on two levels: internal warnings and internal faults.
Internal warnings effects only the concerned part of the relay's functionality, for
other parts the relay will continue normal operation. The internal warnings are
indicated as events and as alarms, if enabled in the configuration, on the HMI and
on remote systems.
In case of internal faults, the relay operation will be disabled, IRF output relay
will be de-energized and corresponding events and alarms issued. REX640 has a
mechanism for recovering from internal fault situation by activating a controlled
restart of the relay. Depending on the root cause, the restart can happen several
times and if successfully the relay will resume full operational status.
When these supervision features are utilized and actions taken in case any of
the supervision functions activates itself, we recommend applying the five years
periodic testing interval.
8.1.2.3 Test Records
During pre-commissioning, commissioning, and periodical testing stages it is
important to record the test cases and test results. The records shall be on such
a detailed level that they can be used to detect any signs of protection performance
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REX640
Operation Manual