- Thread starter Tally
- Start date
EM1L4
Member
- Messages
- 392
- Location
- UK Warwickshire
Clip on amp meter... https://www.tlc-direct.co.uk/Produc...MIp7PHg6aa8AIV4-jtCh0zjwXfEAQYCiABEgKUv_D_BwE
daleyd
Member
- Messages
- 10,419
- Location
- Wrexham, North Wales
Clamp meter - it clips around one phase conductor at a time and will give you a pretty accurate reading of what it’s pulling. Ones marked “true rms” can give more accurate readings on non sinusoidal or distorted waveforms which you can get from inverter welders, not sure if that would affect the supply side of the machine or not though? 
Just 1 phase line?Clamp meter - it clips around one phase conductor at a time and will give you a pretty accurate reading of what it’s pulling. Ones marked “true rms” can give more accurate readings on non sinusoidal or distorted waveforms which you can get from inverter welders, not sure if that would affect the supply side of the machine or not though?
brightspark
Member
- Messages
- 41,253
- Location
- yarm stockton on tees
peak hold and inrush current. yep clip it on one phase
3 phase confuses me.. machine manual says it pulls 18a maxed out.. so if i maxed out the machine would i actually get 18a reading on the clamp meter or do i need to do a bit of maths?
daleyd
Member
- Messages
- 10,419
- Location
- Wrexham, North Wales
Yes - if you clipped around all 3 phases the currents would cancel each other out, but generally in a 3 phase system it should be pretty balanced in what it takes from each phase (give or take, one phase may be powering the control circuits but it’s not going to be a massive difference unless there’s some problem). You can quickly unclip and put around another phase if someone else is doing the welding (obviously make sure it’s safe of course) to check all 3 if you wanted.
I have seen some fancy ones that will measure 3 phases at once but they are pretty specialised and not cheap.
Yes you should get a reading of around 18amp on all three of the phases.
brightspark
Member
- Messages
- 41,253
- Location
- yarm stockton on tees
they also measure single phase both over the live and neutral
very handy if your doing a lot of measuring but single core measuring s ok providing the leads are long enough in an enclosure to clamp the lead overtimgunn1962
Member
- Messages
- 352
- Location
- Lancashire UK
For 3-phase, It's usually a case of measuring each phase in turn with a clip-on ammeter. In most cases, they'll be pretty close and, once you've satisfied yourself of this, you can just take readings from a single phase at each welding setting. If you need to prove the readings for contractual reasons, you will probably need a 3-phase meter with traceable calibration and logging.
If it's awkward to get the clamp meter in, it's a good idea to make a short extension lead with single-core cables, so you can safely get onto each phase.
If it's awkward to get the clamp meter in, it's a good idea to make a short extension lead with single-core cables, so you can safely get onto each phase.
right so all 3 should say 18a aye? if thats the case then i can use a calculator to work out how much power that is to size up a generator then
brightspark
Member
- Messages
- 41,253
- Location
- yarm stockton on tees
some welders just use 2 of the phases .take the highest reading of any of the phases . 2 should be the same or all 3
mtt.tr
Member
- Messages
- 8,462
- Location
- Essex/Suffolk border
just clamp one at a time, as if you clamp all 3 the current on one of the phases will be flowing in the opposite direction it will be subtracting.
Clamp one at a time and take your highest reading as the current drawn, most likely they will be close unless its 2 phase
daleyd
Member
- Messages
- 10,419
- Location
- Wrexham, North Wales
I’d be careful going down that route - welder manufacturers usually spec the generator a fair bit higher than what the incoming power requirement is. There will be peaks and troughs which you might not see on a meter if you don’t know what you are looking for, undersize the generator and your welder could go bang (esp if it’s an inverter machine). If it’s a recent machine I’d be looking at what size generator the manufacturer recommends.
If it’s an older machine or you can’t get info from manufacturers I’d give yourself some margin above what you read as incoming current.
I would go for a minimum of 15 kva
