Main Power Transformer Supernova 3760 XE

[southseas]

Back in February I had completed about 1200 tests with my Supernova 3760 XE for the month, when I noticed that when an Insulation Resistance Test was performed, the test value returned would decline- 99Meg, 63 Meg, 10 Meg till it would fail appliances that had previously just passed as OK. After a day or two of doing this, it stopped working altogether (would not turn on). I returned it to my nearest Seward Agent, who found that the main power transformer had cooked it's self, they couldn't suggest any reason.

Subsequently, I've purchased a secondhand Supernova 3760 XE, about 6 months older than my orgional machine, last month I completed about 1100 tests with it, when it started to display the same symptoms as my first did (declining Insulation Resistance Test values on known items)- neither machine gave any warning about over heating, and a reasonable mix of test types were being conducted.

Is this a common problem, or has muggins just got two duff machines off the assembly line?

Is there a way of viewing the overall number of tests a Supernova has conducted?

[southseas]

So does anyone from Seaward monitor these Forums? Just checked the Voltage produced for Insulation Resistance test, Supernova with replaced Power transformer 546V DC, suspect SuperNova 2.4v DC- so looks like it's time to send that one away.

Can't say I'm impressed by your products guys

[Gary Aspinall]

Hi Southseas,

Our support team is looking into your question and will post a response shortly.

Kind regards,
Gary

[Jim Wallace]

Hi Southseas

The insulation voltage generator is powered from the main power transformer so it is likely that the fault in the insulation voltage generator caused the main power transformer to fail. The product has been on the market for around 15 years with no history of problems with the insulation circuit.
Do you have any more details of what you were testing when the unit failed?

[southseas]

Normal mix of office equipment, power boards, leads and IT equipment, some three phase leads/equipment- so reasonable mix of 25A Earth Bond and 200mA Continuity tests, Insulation and current leakage to AS/NZS3760. Nothing weird or wonderful, the only common denominator would seem to be the number of tests run 1200 over three weeks in Feb and around 1000 for June- where previously 600 or 700 per month was the average.

[Jim Wallace]

Hi Southseas

A run rate of 1200 appliances over 3 weeks should have no impact on the performance or reliabiltity. We have users performing 100-200 tests per day. The insulation voltage generator is protected against short circuits on the output so even if the insulation on an appliance has broken down this wont stress the generator. Is there any possibility that any of the appliances had a voltage on the parts were the probe was connected?

[southseas]

Yeah Jim, that was 1200 in three weeks so was an average of just over 100 per day, Insulation tests were all done on Single Phase items plugged directly to SuperNova- in the case of three phase items, I have a 3ph socket wired to a single phase plug and connected to PAT via that to run insulation tests- So the insulation Probe wasn't used at all.

Could repeated earth bond tests (25A) cause this? I use the earth bond to check phasing on 3Ph Extension leads ( 4 earth bond tests per cable adds up) Earth bond also on Power Boards too.

[Jim Wallace]

Hi Southseas

The earth bond tests has its own transformer which is totally seperate from the insulation/power transformer so can't see how it could effect the insulation test. Similarly, testing 3 Ph equipment via an adaptor should not cause a problem or present any over load or over-voltage to the insulation voltage source.

[southseas]

Is there any aftermarket way of cooling SuperNovas?- did 110 tests in 6 hours yesterday, and started to get the "over heating" warning for the last few. I do have two, do I need to work these in shifts, one hour of testing with one, then swap over to the other for an hour, and so on.

Go the mighty AB's

[southseas]

Last week, my backup SuperNova started giving declining resistance tests (same as Number One) so I just kept hitting retest until it too went the same way as the first- a quiet pop, the screen went blank and that's all folks.

So that's two different testers in two years, with the same fault- any thoughts? I do run leakage tests on items, basically only up to items that pull 8-9 Amps- could that be a cause?