14.2.2.5 Self supervision check
Once secondary testing has been completed, it should be checked that no self-supervision
signals are activated continuously or sporadically. Especially check the time
synchronization system, GPS or other, and communication signals, both station
communication and remote communication.
14.2.2.6 Trip circuit check
When the protection IED undergoes an operational check, a tripping pulse is normally
obtained on one or more of the output contacts and preferably on the test switch. The
healthy circuit is of utmost importance for the protection operation. If the circuit is not
provided with a continuous trip-circuit supervision, it is possible to check that circuit is
really closed when the test-plug handle has been removed by using a high-ohmic
voltmeter and measuring between the plus and the trip output on the panel. The
measurement is then done through the trip coil of the circuit breaker and therefore the
complete trip circuit is checked.
Note that the breaker must be closed.
Please observe that the test system does not provide built-in security
during this test. If the instrument should be set on Amp instead of Volts,
the circuit breaker naturally is tripped, therefore, great care is necessary.
Trip circuit from trip IEDs to circuit breaker is often supervised by trip-circuit
supervision. It can then be checked that a circuit is healthy by opening tripping output
terminals in the cubicle. When the terminal is opened, an alarm shall be achieved on the
signal system after a delay of some seconds.
Remember to close the circuit directly after the test and tighten the
terminal carefully.
14.2.2.7 Measurement of service currents
After a maintenance test it is recommended to measure the service currents and service
voltages recorded by the protection IED. The service values are checked on the local HMI
or in PCM600. Ensure that the correct values and angles between voltages and currents are
recorded. Also check the direction of directional functions such as Distance and
directional overcurrent functions.
Section 14 1MRK 504 165-UUS -
Commissioning and maintenance of the fault clearing system
300 Transformer protection RET670 2.2 ANSI
Commissioning manual
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