Proving units maximum voltage

[Ziggie]

I decided,having lived with using a live circuit, to buy a proving unit. I opted for a Kewtech Prove 4 which covers 5 voltages between 690volts and 50 volts. The device starts at 690 volts which is ok for my Megger 2 pole tester. My fluke clamp meter has a limit of 600 volts. The second problem is that the unit spends only seconds in the low voltage ranges and it’s too fast to check the readings easily in these ranges.

Has anyone used this device with testers that have lower limits than the 690 volts ?

 

[newfutile]

A proving unit is not really to check the voltage readings , just to prove your approved voltage tester is working both before and after testing the isolated (and locked off) device.

you have to test at or above the voltage you expect to find on the device under power.

 

[DPG]

I think what he means is that the kewtech unit outputs 690V initially, which is above the maximum limit of his Megger voltage tester.

The Kewtech one starts off at 690V and if you hold the probes in it will step the voltage down every second or two. This is to do a full test of the kewtech voltage probe, so that you can confirm each voltage range is working OK

 

[nicebutdim]

Fluke PRV240 puts out 240V AC/DC. Martindale PD440 will give 440V AC. Neither offers a range of voltages.

 

[pc1966]

All voltage testers are safe to much higher than the "rated" voltage. Going 10-20% over spec is not a problem and anything for power system use in the UK should be CAT-III or CAT-IV anyway:

Measurement category - Wikipedia

en.wikipedia.org

 

[nicebutdim]

I have a socket and see unit that turned up cheaply somewhere. It lights up and squeals when stabbed with probes, which is more than adequate for my basic requirements.

 

[Ziggie]

My fluke clamp meter says don’t use if voltages greater than 600volts - and the kewtech starts at 690 volts and you can’t say “please start lower than 690 volts.

 

[Ziggie]

If the proving unit had started at the low end (50volts) and slowly rise to the higher voltages where you could halt before going to higher voltages by removing the probes surely would have been safer ?

 

[brianmoooore]

I suspect the 600 volt limit is the max. rating of the leads Cat iv GS38 thing.

 

[DPG]

I think suitable devices have been given in post 4 by nicebutdim.

 

[Moley]

What voltage do you want to go to? On ebay there's a Martindale 440 buy it now at £40 or a 240v buy it now at £38

 

[Ziggie]

I suspect the 600 volt limit is the max. rating of the leads Cat iv GS38 thing.

Could be but it is g do ocumented in the meter document without mentioning leads

 

[pc1966]

It is odd to start high and go down, that is for sure. The one I have is this and it ramps up:

4299 Proving Unit

Intelligent voltage ramp testing for voltage indicators and multimeters

www.cef.co.uk

If you have a tester that is rated for 690V then I would use it for everything that might be live. Generally I prefer simpler as I don't like the continuity buzzer on mine, and it means yet another battery to remember and change before it leaks...

Next time I'm getting a simple one without battery requirement, or a Drummond if I'm feeling flush.

 

[Ziggie]

It is odd to start high and go down, that is for sure. The one I have is this and it ramps up:

4299 Proving Unit

Intelligent voltage ramp testing for voltage indicators and multimeters

www.cef.co.uk

If you have a tester that is rated for 690V then I would use it for everything that might be live. Generally I prefer simpler as I don't like the continuity buzzer on mine, and it means yet another battery to remember and change before it leaks...

Next time I'm getting a simple one without battery requirement, or a Drummond if I'm feeling flush.

I use the one that’s rated to 690 volts to test for dead circuit and use my fluke for accurate measurements of voltage and current.

 

[pc1966]

In the ideal world everything is routinely calibrated, but in between you really want some "sanity check" that all is still OK. More so if you just dropped it, or someone else borrowed it, etc.

So if it is not for proving dead then you only need to check on something occasionally to see it is working OK. Just using the 230V mains is an option, but if it does DC then a check on a 9V battery is enough! If you have any other meter or a MFT then you can compare readings and see they agree to 1-2% or whatever the accuracy specifications of them is.