42
1MRS 752264-MUM
Motor Protection Relay
Operator’s Manual
REM 610
4.6.
Testing of protection functions
The short-circuit and earth-fault protection functions in the relay can be tested with
the setting values used during normal operation. If other settings are used during
testing, you should make sure that the original settings are re-entered after the test is
completed.
The test is performed as a secondary test, by injecting current to the current
energizing inputs. To enable secondary testing without accidentally blocking other
relays or tripping circuit breakers in the system, the relay has to be disconnected.
4.6.1.
Testing of the short-circuit protection
If proper 3-phase secondary testing equipment is not available for current
generation, the phase unbalance and phase reversal protection functions have to be
out of operation during the test.
When calculating the current to be injected into the phase current energizing inputs,
the calculation should be done on the basis of the following:
the rated current, 1 A or 5 A, of the relay energizing input to be tested
the protected unit scaling factor (used for motor full load current compensation)
This gives the current to be injected during the test as follows:
injected current (A) = 2.5 x I>> x Rated current of the energizing input x
protected unit scaling factor
To perform the test, inject the current in all three phase current energizing inputs.
The output contacts, to which the trip signal is routed from the short-circuit
protection function, should be activated on the expiration of the set operate time of
stage I>>.
4.6.2.
Testing of the earth-fault protection
When calculating the current to be injected into the
earth-fault
current energizing
input, the calculation should be done on the basis of the following:
the rated current, 1 A or 5 A, of the relay energizing input to be tested
This gives the current to be injected during the test as follows:
injected current (A) = 2.5 x I
0
> x Rated current of energizing input
To perform the test, inject the current in the earth-fault current energizing input. The
output contacts, to which the trip signal has been routed from the earth-fault
protection stage, should be activated on the expiration of the set operate time of stage
I
0
>.
Caution!
For the limited current carrying capacity of the wiring, terminals
and measuring transformers of the relay, refer to the Technical
Reference Manual.
!
