EDR-5000 IM02602007E
Commissioning: Overcurrent Protection, directional [67]
Object to be tested
For each directional overcurrent element is to be measured: the total tripping time (recommendation) or alternatively
tripping delays and the dropout ratios; each time 3 x single-phase and 1 x three-phase.
Especially in Holmgreen connections, wiring errors can happen easily and
these are then detected safely. By measuring the total tripping time, it can be
ensured that the secondary wiring is o.k. (from the terminal on, up to the trip
coil of the breaker ).
It is recommended to measure the total tripping time instead of the tripping
time. The tripping delay should be specified by the customer. The total tripping
time is measured at the position signaling contacts of the breakers (not at the
relay output!).
Total tripping time: = tripping delay (please refer to the tolerances of the
protection stages) + breaker operating time (about 50
ms)
Please take the breaker switching times from the technical data, specified in
the relevant documentation, provided by the breaker manufacturer.
Necessary means
Synchronizable current and voltage sources
May be: ampere meters
Timer
Procedure
Synchronize the 3-phase current and voltage sources with each other. Then simulate the tripping directions to be tested
by the angle between current and voltage.
Testing the threshold values
(3 x single-phase and 1 x three-phase)
Each time feed a current which is about 3-5% above the threshold value for activation/tripping. Check then 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 trip delay (measured at the relay output)
Measure the tripping times at the relay output.
Testing the dropout ratio
Reduce the current to 97% below the trip value and check the dropout ratio.
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