Hi-Pot Testing

The term "Hi-pot" implies that you are in USA/Canada. Can't help you in that case, someone else surely will.

For what it is worth, i give below an extract of IEC 60947-1 which specifies 100mA for power-frequency tests. Seems rather high to me, but there it is ...

Try this Google search page: http://www.google.com/search?q=high+pot+testing+technique&sourceid=ie7&rls=com.microsoft:en-us:IE-SearchBox&ie=&oe=

If you don't find your answer there, change the search criteria to expand your options.

What are you testing? The value of the trip current depends on the appliance, i.e. light fittings is 5 mA at 1.5 kV.

The relay should be set as per the current rating of the equipment. The condition of the equipment under test would decide the current drawn from the High voltage test source. Generally the charging current drawn depends on the capacitance of the equipment under test and the test voltage. For example a conventional High voltage source may not be able to supply the charging current drawn by a large size generator ( more so when the windings under test are water cooled). In conventional windings also if the outer surface of the windings are badly contaminated then also it may draw heavy current from the HV source. So best way would be to go as per the recommendations of the manufacturer of the HV source manufacturer.