testing electrical equipment

[cjdelphi]

I was watching fake Britain showing off those cheap chinese hover boards and the segment was on lithium batteries..

Taking not too much notice until i heard the word test and power supply, anyway he connected a machine generating 3 - 5k volts and then fed it into the 240ac input... the machine for a good few seconds showed no high voltage coming out the dc plug end until beeeeeeep it failed then came the safety spill, sorry but i'd like to see a samsung or apple charger handle 3kv and not do the same!...

1. Why 3k volts? That's surely enough to arc through 240v circuits burn tracks and eventually lead to a short?

2. How can 3kv be a fair test, nobody puts 3kv through a switch mode power supply!

 

[shrtrnd]

Kinda reminds me of that old TV news report, where they rigged a truck to explode to 'prove' the fact that the gas tank blow-up when that particular vehicle is 'involved in an accident'.
Like statistics, you make the rules to show the result you want.

 

[Arouse1973]

It should be for testing the resistance to mains fluctuations from lightning strokes and other surges.
Adam

 

[cjdelphi]

Mains fluctuations...

I'd be very very worried if i was seeing 2kv spikes on a 240 supply

 

[Arouse1973]

Mains fluctuations...

I'd be very very worried if i was seeing 2kv spikes on a 240 supply

Why... it happens all the time in other countries also. Next time you wire a plug, take note of the distance between the terminal. Why are they that far away?
Adam

 

[cjdelphi]

Why... it happens all the time in other countries also. Next time you wire a plug, take note of the distance between the terminal. Why are they that far away?
Adam

Happens all the time? (2kv spikes) you can't be serious, MOVs would be burning out all over the place!

 

[Bluejets]

Can you point towards the type of test equipment used.

I'm guessing it was an "appliance tester" of which there are many type available these days.
Operation of these devices do not inject 2 to 3 kv that I am aware of, more like 500v which is the standard insulation test voltage for 240v equipment.
There is also a low voltage injection for the earth continuity if applicable.
These particular devices are now used where a megger was previously and main purpose is to speed up and make the testing a simpler operation with no "omitted" proceedures,
Machine does a routine array of tests depending on selection of target type and returns a result.
This also makes it possible for people like carpenters etc. to be issued a permit to test their own portable equipment like extension leads, drills etc.

Mov's can be a problem and one has to be aware of the device unter test and make allowances for such.

Overall it is the usual, experience, education and understanding of what is happening to interpret the result.
Also applies to watching tv programs.

 

[Arouse1973]

Happens all the time? (2kv spikes) you can't be serious, MOVs would be burning out all over the place!

If you want your equipment to be put on the market in Europe and it operates from the mains you have to test to the LVD. Part of these tests include transient response. This is IEC 61000-4-xx and below shows a chart of test level criteria for power ports and I/O.
Thanks
Adam