A tad more information may be required here. Cable age, length, insulation type, cable construction, conductor capacitance, termination type to start with would be very handy.
In addition to typical insulation and conductor tests, I have performed Statistical Switching TOV (Transient Overvoltage)Analysis using ATP software. This is used to determine the adequacy of the insulation systems or the cable, along with the BIL ratings of attached equipment and MOV arrestors. It is a simulation of 100 random pole energizations (step voltage) and review of the resulting graphs.
I think for UK IEC 60502-2 could be the recommended test standard.
According to art. 20 "Electric tests after installation" there are 2 tests:
20.1 D.C. voltage test of the oversheath( but the voltage level and duration according Clause 5 IEC 60229)
applied between the shield and the ground.
20.2 Insulation test [recommended a.c. test] 5 min. phase-to-phase applied between conductor and ground or
24 hours normal operating voltage of the system, or a D.C test of 4*voltage to ground rated[may reduce the cable life!].
There is a note [2] :
NOTE 2: For installations which have been in use, lower voltages and/or shorter durations may be used. Values
should be negotiated, taking into account the age, environment, history of breakdowns and the purpose of carrying
out the test.
IEEE-400.2 recommends a Very Low Frequency [VLF]test and for cables of 8kV indicates 14 kV for 15 min.
IEEE-141[Red Book] recommends [art.12.11.1 Application and utility]:
"Personnel with adequate technical capability should be available to do the testing, make observations, and evaluate the results. The procedures discussed in this chapter are recommended practices, and many variations are possible. At the same time, variations made without a sound technical basis can negate the usefulness of the test or even damage equipment."
Table 12-9 specify cable field test voltages [D.C. !] For instance, if the cable rated voltage is 15 kV then the test will be 41 kV D.C.[ this is more than required by 60502-2 only 34.64 kV].
So ,as mentioned in above posts, one need more experience to state how to test the cable.
