Phase rotation advice

[shaun1]

Does it always show no rotation L2 to L3? Does it always show correct rotation between other phases? If so that would suggest there is something different about that measurement, but probably worth checking with a second meter.

If you use the probes the other way round do you get Phase rotation (the opposite way)?

When you added the load from the heater did you still get 400v between all phases?

 

[Wilko]

If you are doing what Pete's video shows and you are only seeing rotation in 2 phases, then doesn't that mean you only looking at 2 phases? Test method, test instrument or labelling wrong perhaps?

 

[shaun1]

If you are doing what Pete's video shows and you are only seeing rotation in 2 phases, then doesn't that mean you only looking at 2 phases? Test method, test instrument or labelling wrong perhaps?

I think the confusion comes from the fact that the meter still indicates 400v L2 > L3

 

[Wilko]

To add to the confusion, when I load tested the generator, all three phases displayed correct rotation.

Ok - so what is different in these two situations?

 

[Pete999]

You need a new tester Phil.

I could be barking up the wrong tree, your tester Phil does not have the L1 L2 markings, although there there are L/R sequence lamps, as I say maybe completely wrong, but are you sure the tester show is capable of doing Phase Sequence testing? It's just a thought. Could it be as someone has already said, your test method is wrong?

 

[davesparks]

How good is the earth reference for the generator? Those two wire rotation tests rely on the source being properly earthed as they take an earth reference via capacitive coupling to the hand of the operator.

I think you'd be better off testing phase rotation with a proper phase rotation tester or mft with this function.

You said the generator is shutting down on reverse power, is it running in parallel with other generators?
Reverse power on a generator normally means that power is feeding in to this generator from another connected generator or other source.

 

[Pete999]

How good is the earth reference for the generator? Those two wire rotation tests rely on the source being properly earthed as they take an earth reference via capacitive coupling to the hand of the operator.

I think you'd be better off testing phase rotation with a proper phase rotation tester or mft with this function.

You said the generator is shutting down on reverse power, is it running in parallel with other generators?
Reverse power on a generator normally means that power is feeding in to this generator from another connected generator or other source.

Backfeeding, of course, wondered what the OP meant with reverse power.

 

[westward10]

I think he means when the connected hoist motor which the generator supplies is reversed the genny shuts down.

 

[telectrix]

i think it's time for a beer.

 

[Pete999]

i think it's time for a beer.

Or that medication you were ion about ealier

 

[westward10]

If the generator runs the hoist in one direction but not the other I suspect the problem lays not with generator but the hoist. The reverse direction may be placing more load on the generator and it is locking out/shutting down.

 

[Lucien Nunes]

If there is no other load on the genny but the hoist, then when the hoist lowers it might well regenerate into the genny and trip it with reverse power. Motors can regenerate into the grid as it has a near infinite capacity to absorb reverse power (think solar!) but a standalone genny can't absorb much power without risk of its AVR losing control, hence its panel is configured to detect this and trip the supply. It might be set too sensitive, but if reverse power is genuinely the problem, adding some load in parallel will solve it.

Agree with Davesparks - 2-wire rotation testers are a fudge - the voltage between any two lines does not have rotation but it detects the relative phasing by capacitive coupling to the outside world like a voltstick. If the supply is not properly earth-referenced (e.g. N-E link is open) or the user is in close proximity with something elevated from earth, then the indication can be misleading. I don't use or trust them, only 3-wire rotation testers can give an authoritative answer.

 

[freddo]

the voltage between any two lines does not have rotation but it detects the relative phasing by capacitive coupling to the outside world like a voltstick.

Yes and to work properly they normally need to be gripped firmly in your hand, not just lying on top like in your video.

 

[UKMeterman]

A quick idea, leave the heater connected and check the hoist again.

 

[Phil]

Thank you all for your replies, I'm sorry I have not been back on the forum to reply, as soon as I finished that job I was up to Aberdeen to sort another break down.

Just to clear things up, my company just supplied the generator, another company sized the generator and done the wiring to the hoist.

When the hoist engineer turned up we were able to start testing, massive voltage drops when operating the hoist and as someone mentioned previously the hoist was causing the reverse power.

Phoned the company that done the wiring for them to get 16mm cable and they argued they sized the cable correctly and then asked if we can not just turn the voltage up on the generator??? Anyways event got them to replace the cable and hey presto, it's all sorted.

The company does have a proper all singing tester but that stays in the depot so only had my personal tester with me.

I thank you all again for your answers and for your time!

 

[Pete999]

Thank you all for your replies, I'm sorry I have not been back on the forum to reply, as soon as I finished that job I was up to Aberdeen to sort another break down.

Just to clear things up, my company just supplied the generator, another company sized the generator and done the wiring to the hoist.

When the hoist engineer turned up we were able to start testing, massive voltage drops when operating the hoist and as someone mentioned previously the hoist was causing the reverse power.

Phoned the company that done the wiring for them to get 16mm cable and they argued they sized the cable correctly and then asked if we can not just turn the voltage up on the generator??? Anyways event got them to replace the cable and hey presto, it's all sorted.

The company does have a proper all singing tester but that stays in the depot so only had my personal tester with me.

I thank you all again for your answers and for your time!

Tester is not much good stuck in the main Depot, when all the problems that need testing are out on site, ofr is the tester someones special purchase?

 

[Phil]

Tester is not much good stuck in the main Depot, when all the problems that need testing are out on site, ofr is the tester someones special purchase?

I take the tester with me when I'm going to electrical break downs from the depot, in this case I went straight from another job, but I can't keep it in the van as we need it to RCD test the generators before they go out on hire.

It's only a small company, the only just started spending money on the electrical side of things since I started last year.

My own collection of tools and testers is small compared to what most you guys will have. I've been in the army for the last 13 years and all tools etc was provided, I'm slowly buying my own stuff, already spent 100s since starting with this company.

 

[Pete999]

I take the tester with me when I'm going to electrical break downs from the depot, in this case I went straight from another job, but I can't keep it in the van as we need it to RCD test the generators before they go out on hire.

It's only a small company, the only just started spending money on the electrical side of things since I started last year.

My own collection of tools and testers is small compared to what most you guys will have. I've been in the army for the last 13 years and all tools etc was provided, I'm slowly buying my own stuff, already spent 100s since starting with this company.

All my tools were provided Phil so I know how you feel