At mode
2 out of 4 the phase current setting, IP> can be checked by single-phase injection
where the return current is connected to the summated current input. The value of residual
(earth fault) current IN set lower than
IP> is easiest checked in back-up trip mode 1 out of 4.
12.5.9.1
Checking the phase current operate value,
IP>
M12104-23 v12
The check of the
IP> current level is best made in FunctionMode = Current and BuTripMode = 1
out of 3 or 2 out of 4.
1.
Apply the fault condition, including START of CCRBRF, with a current below the set
IP>.
2.
Repeat the fault condition and increase the current in steps until a trip occurs.
3.
Compare the result with the set
IP>.
Note! If
No CBPos Check or Retrip off is set, only back-up trip can be used to
check set
IP>.
12.5.9.2
Checking the residual (earth fault) current operate value
IN> set below
IP>
M12104-80 v9
Check the low set
IN> current where setting FunctionMode = Current and setting BuTripMode
=
1 out of 4
1.
Apply the fault condition, including START of CCRBRF, with a current just below set
IN>.
2.
Repeat the fault condition and increase the current in steps until trip appears.
3.
Compare the result with the set
IN>.
4.
Disconnect AC and START input signals.
12.5.9.3
Checking the re-trip and back-up times
M12104-93 v10
The check of the set times can be made in connection with the check of operate values above.
Choose the applicable function and trip mode, such as
FunctionMode = Current and
RetripMode = CB Pos Check .
1.
Apply the fault condition, including start of CCRBRF, well above the set current value.
Measure the time from START of CCRBRF.
2.
Check the re-trip
t1 and back-up trip times t2 and t3.
In applicable cases, the back-up trip for multi-phase start
t2MPh and back-up trip 2, t2
and
t3 can also be checked. To check t2MPh, a two-phase or three-phase start shall be
applied.
12.5.9.4
Verifying the re-trip mode
M12104-36 v6
Choose the mode below, which corresponds to the actual case.
In the cases below it is assumed that
FunctionMode = Current is selected.
Checking the case without re-trip,
RetripMode = Retrip Off
M12104-107 v6
1MRK 502 067-UEN B
Section 12
Testing functionality by secondary injection
165
Commissioning manual
