power Cable testing

Hello "Guest"

Which "Cable Drums" are you talking about?

What test voltage and AC or DC were you using.

For how long was the Test voltage applied.

Where did the "spark" come from?

My best guess as to your Question:

If you are talking about a new drum of cable, with one end sealed by the makers, and you were testing from the end you opened up, the capacitance of the cable will enable it to store large amounts of energy if you used a 5kV DC supply to test the cable.

After you disconnect the test supply, the cable is still holding the charge voltage, perhaps for several days.

Ensure after all High Voltage testing, that charged conductors and equipment is correctly discharged, or yourself or others may suffer injury or death.

As you may see from my reply, I am guessing at your problem, and thus my best (so far) answer, because you need to be more specific.

Reply with

Why remain as a Guest. Register at and enjoy helping others.

Kind Regards....

Insulation breakdown. It is an expression of the cable failing the test.

Residual charges. You have to discharge cable after testing megger.

Nope! Sparkstation got it right the first time. Saw the same problem/phenomenom when I was doing dielectric testing of power cables when I worked for Hydro. Evidently "Guest" isn't using proper test equipment or else not following procedure. Either will get someone killed sooner rather than later.

If you are not competently trained in high voltage testing, you are risking severe injury and/or death. It is imperative that you know and follow proper HV testing procedure(s) at all times.

Where is the arcing occurring?

If you are testing cable wrapped on a drum (reel?) and do not have control of both ends of the cable, the distance between the conductors at either end could be insufficient to prevent arcing between the conductors and/or whatever it is attached to.

One-time acceptance testing for new electrical apparatus is: 2E + 1,000 (2 x rated voltage) + 1,000. If the cable in this case is used, do not exceed the manufacturer's nominal voltage rating stamped on the cable. If you are not exceeding the manufacturer's rating, and the arcing is occurring at a specific location (other than at an end), or at intervals along the length of the cable, the insulation has failed and the cable should not be used for any reason.

If you are not absolutely sure of what you are doing, get competent help before continuing.

Good luck and be very careful.

Is the cable a continious lenght or are there welds in the calbe that could have broken inside the insulation and a spark burnt thru to the outside ?

Hello dadw5boys

In the usual manner of Guest Topic Starters, I venture to state that the Original Topic Starter Guest shall not bother to give a proper response.

Of course "Guest" could reply, but there is currently no way of determining which "Guest" is which.

If the cable is "On the reel" as stated, the "spark" is almost certainly the built-up charge in the cable, after using HV test equipment without making certain the stored charge was properly and safely discharged, refer my best guess here:http://cr4.globalspec.com/comment/282485/Re-power-Cable-testing

Kind Regards....

In cutting fixed lenghts for aircraft wiring bundles our test blew out broken welds in stranded cables up to 4/0 Nickle Plated power cable.

Plus I just like to ask questions .