Onload Checks; Final Check - GE P50 Agile P253 Technical Manual

11 Commissioning Instructions
Using (2) k = Ieq/ IFL= (2 x 2 /√3) / 0.5 = 8/√3 A
= 5 x 60 ln ((8/√3)
t
op
For a thermal alarm setting = 90% using (2) t
If the injection is done equally on the 3 phase current transformers, the equation used to calculate Ieq
will be
= √ (I
I ² + (K Coefficient* I
rms
eq
And provided the phase currents are balanced, I
When the tests are complete, go to the CONFIGURATION column and restore all previously disabled
protection elements to their original settings.
2.1.13

Onload Checks

Onload checks can only be carried out if there are no restrictions preventing the energisation of the
plant, and the other devices in the group have already been commissioned.
Remove all test leads and temporary shorting links, then replace any external wiring that has been
removed to allow testing.
Caution:
2.1.13.1 Onload Checks
1. Measure the current transformer secondary values for each input using a multimeter
connected in series with the corresponding current input.
2. Check that the current transformer polarities are correct by measuring the negative sequence
current magnitude. or derived earth fault current.
3. Ensure the current flowing in the neutral circuit of the current transformers is negligible.
4. Compare the values of the secondary phase currents with the measured values. This
information can be found in the MEASUREMENTS menu.
The 'Secondary 'values displayed on the relay should be equal to the applied secondary current. The
values should be within 2% of the applied secondary Current. However, an additional allowance must
be made for the accuracy of the test equipment being used.
2.1.14

Final Check

1. Remove all test leads and temporary shorting leads.
2. If you must disconnect any of the external wiring to perform the wiring verification tests,
replace all wiring, fuses and links in accordance with the relevant external connection or
scheme diagram.
3. Ensure the IED is restored to service by checking the Test Mode cell in the COMMISSION
TESTS menu is set to 'Disabled'.
4. The settings applied should be double checked against the required application-specific
settings to ensure they have not been altered during testing.
5. Make sure all the required protection elements have been set to Enabled in the
CONFIGURATION menu.
6. The circuit breaker maintenance and current counters should be zero if the IED is in a new
installation or the circuit breaker has just been maintained. These counters can be reset using
the Clear Maint function in the RECORD CONTROL menu.
11-10
/ ((8/√3)
2 2
– 1)) = 14.4 s
²)
2
If any external wiring has been disconnected for the commissioning
process, replace it in accordance with the relevant external
connection or scheme diagram.
= 12.96 s
alarm
is zero.
2
P50 Agile P253
P253/EN M/C