Phase rotation advice

[Phil]

Hello all,
I'm after some advice on my current situation as I've never came across this before and trying to find answers online are not producing any results.

Basically I've got a 3 Phase motor, checked voltages across the 3 lines and neutral, everything is as it should be.

Checked rotation, L1 to L2 ok, L2 to L3 is not showing rotation but it's showing 400V, L3 to L1 is ok.

Why would L2 to L3 not show rotation but will show 400V?

Thank you for any advice.

 

[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