Millivolt Drop Test - 11kV VCB

Do you mean measurements of the resistance of the circuit breaker main contacts?

Measurement of resistance for all joints and bus bar with main contacts for 11kV Vaccum circuit breaker.

why higher resistance is sever and what could happen.

How we decide trolley voltage and current for measurement.

Is there is any detail document for measureemnt of resistance (mili volt) for 11kV inddor circuit breaker.

The high resistance could be due to the following:
- improper alignment of the circuit breaker inside its cubicle;
- accumulation of layers on the main contacts due to frequent arc and lake of periodic maintenance;
- bad connections due to bad joints;
- inappropriate way in conducting the test.

Have a look on the contents of the below links.

http://www.bertholdelectric.com/bertholdElectric/resistanceTests.asp

http://www.elp.com/index/display/article-display/0995654051/articles/utility-products/volume-7/issue-2/reader_s-choice_awards/testing-high_voltage.html