4.8.1
Commissioning: Overcurrent Protection, Non-directional [ANSI
50P]
Object to be tested:
•
Signals to be measured for each current protection element: the threshold values,
total tripping time (recommended), or alternatively tripping delays and the drop-out
ratios; each time 3 x single-phase and 1 x three-phase.
NOTICE!
Eaton recommends measuring the total tripping time instead of the tripping delay. The
tripping delay should be specied by the User. The total tripping time is measured at the
position signaling contact of the breaker (not at the relay output contacts!).
Total tripping time = tripping delay (please refer to the tolerances of the protection
elements) + breaker operating time (about 50 ms)
Please take the breaker operating times from the technical data specied in the relevant
documentation provided by the breaker manufacturer.
Necessary means:
• Current source;
• Current meters;
• Timer.
Procedures:
Testing the threshold values (3 x single-phase and 1 x three-phase)
For each test performed, feed a current that is about 3-5% above the threshold value for
activation/tripping. Then check the threshold values.
Testing the total tripping delay (recommendation)
Measure the total tripping times at the auxiliary contacts of the breaker (breaker
tripping).
Testing the tripping delay (measuring at the relay output contact)
Measure the tripping times at the relay output contact.
Testing the drop-out ratio
Reduce the current to 97% below the trip value and check the drop-out ratio.
Successful test result
The measured total tripping delays or individual tripping delays, threshold values, and
drop-out ratios correspond with those values specied in the adjustment list. Permissible
171www.eaton.comEMR-3MP0
4 Protective Elements
4.8 50P – DEFT Overcurrent Protection
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