Voltage Optimisers.

[kitlearie]

Has anyone come across a phase sequence fault when switching on a voltage optimiser for the first time. The system is a cheap chinese one I think with terrible instructions.

Can a voltage optimiser know if your input wiring is black, grey, brown instead of Br, Bl, Gr? I ask because we don't want to have to reverse the wiring on hundreds of 3ph motors on site.

Any ideas why we might be gettiing the phase sequence alarm?


thanks


Kit

 

[Guest123]

Have you actually checked the phase rotation of the site with a rotation meter???

 

[kitlearie]

Yes, the rotation is 2, 1, 3. We left it at that so we would avoid roation direction issues.
Surely the optimiser cannot know its not wired Br, Bl, Gr and also need it to be that way?

thanks

 

[Guest123]

2, 1, 3, is out of sequence so obviously the machine is going to recognise that.

Theres more to phase sequence relationship than just the colour of the cables......

 

[Engineer54]

Yes, the rotation is 2, 1, 3. We left it at that so we would avoid roation direction issues.
Surely the optimiser cannot know its not wired Br, Bl, Gr and also need it to be that way?

thanks

Just because the rotation is L2, L1, L3 on one of the motors doesn't mean all the motors will be the on the same sequence!! All too often electricians will change the line conductors at a convenient point such as an isolator or any other point on the motor circuit if they find the motor running the wrong way after installation....

 

[kitlearie]

When I say the rotation is 2 1 3, I mean this is what the meter showed at the incomer. We kept to this sequence so that all the motors on site will run the correct way. But the Voltaage Optimiser is signaling a phase sequence alarm. We checked output is the same as the input.

thanks

 

[spark 68]

I take it the voltage optimiser has in and out connections ?

If this is the case what is to stop you connecting it with the correct 1-2-3 sequence, so long as the in/out is the same and matched, then your (2-1-3) phase sequence will be maintained?

 

[Engineer54]

Phase sequence, needs to be verified at EACH motor, you cannot assume the sequence will be the same, as at the origin of the the main supply...

 

[malcolmsanford]

I would imagine your optimizer will utilize a phase failure relay which will also detect phase rotation sequence, try swapping the phases coming into the unit

 

[kitlearie]

But if changing incoming sequence makes it opposite of what we originally had all motors on site will run the wrong way. Surely an optimiser must be compatible with the original site, whichever way it was wired.

 

[brman]

but what about Spark 68s question?

 

[Knobhead]

You have got to do line to line live phase sequence testing. The same is done when a new transformer is connected to a board.
Disconnect the optimiser out going from the board. Keep any neutral connected.
Test between the boards bus to the optimiser output.
Brown > Brown
Grey > Grey
Black > Black
Any difference other than a few volts on corresponding phases shows which to swap. Swap the optimiser output to match the main board to keep you phase rotation correct.

 

[Knobhead]

But if changing incoming sequence makes it opposite of what we originally had all motors on site will run the wrong way. Surely an optimiser must be compatible with the original site, whichever way it was wired.

You swap the out going to match

 

[Guest111]

have you considered getting an electrician out? I mean a proper one who knows what he is doing

 

[kitlearie]

Are you saying you can correct a phase sequence issue by altering the outgoing phase sequence? I think the optimiser is telling us that the input sequence is wrong. I believe the Br, Bl, Gr incomers have been switched in a joint box. So the whole premises has always been a , say, 2, 1, 3, sequence. That never mattered as any 3ph gear would be wired accordingly and direction checked. But now a 30 grand optimiser has been fitted and the sparks left the sequence the same so everything would work as it did before. My question is does the optimiser input wiring have to be, to use old colours R Y B? If you think about it there are 6 options - ryb, rby, ybr, yrb, bry and byr - will only RYB work at the input? If so, if an old flour mill with 1000s of 3ph motors has been wired other than a RYB sequence, all the motors will have to be rewired after an optimiser is fitted.

thanks

 

[kitlearie]

I hope your right. But I can't help feeling a change in phase sequence could make motors spin the wrong way.

thanks

 

[Guest111]

any change in phase sequence will change motor direction, think this way if at moment you have for example blue to l1 red to l2 and yellow to l3 at source and everything runs right way then connect red to l1 yellow to l2 blue to l3 from incomer to optimiser then out of optimiser connect l1 to blu phase l2 to red phase and l3 to yellow phase, optimiser should work and motors should run right way.

 

[Knobhead]

Reverse the input and the output to match.

What size is this optimiser? 1000’s of drives you should be looking at an on load tap changer transformer.

I worked for over twenty years on plants where the 11KV feeds were reversed. 18MW running without problems. (Two OLTC 33/11KV 10MVA transformers quite happily running “forwards” feeding the plants “backwards”).

 

[kitlearie]

The optimiser is 600amp. Big sod, weighs a ton - I mean literally one ton.

thanks

 

[Knobhead]

Here have a look at this

View attachment 11479