Woodward HighPROtec MCDLV4, Manual

Page: 751 / 1275

Protective Elements
Testing the threshold values
Configure minimum »
%I2/I1« setting (2%) and an arbitrary threshold value »Threshold« (I2).
For testing the threshold value, a current has to be fed to phase A which is lower than three times the adjusted
threshold value »
Threshold« (I2).
Feeding only phase A results in »
%I2/I1 = 100%«, so the first condition »%I2/I1 >= 2%« is always fulfilled.
Now increase the phase L1 current until the relay is activated.
Testing the dropout ratio of the threshold values
Having tripped the relay in the previous test, now decrease the phase A current. The dropout ratio must not be
higher than 0.97 times the threshold value.
Testing %I2/I1
Configure minimum threshold value »
Threshold« (I2) (0.01 x In) and set »%I2/I1« greater or equal to 10%.
Apply a symmetrical three-phase current system (nominal currents). The measuring value of »
%I2/I1« should be
0%.
Now increase the phase L1 current. With this configuration, the threshold value » Threshold« (I2) should be
reached before the value » %I2/I1« reaches the set »%I2/I1« ratio threshold.
Continue increasing the phase 1 current until the relay is activated.
Testing the dropout ratio of %I2/I1
Having tripped the relay in the previous test, now decrease the phase L1 current. The dropout of »
%I2/I1« has to be
1% below the »
%I2/I1«setting.
Successful test result:
The measured trip delays, threshold values, and dropout ratios are within the permitted deviations/tolerances,
specified under Technical Data.
751 MCDLV4 DOK-HB-MCDLV4-2E