Volt Drop

[Inteificio]

Hi,

I am working on a unit with a large compressor and lighting on a single phase (bad design).

When the compressor kicks in we get a volt drop noticeably dimming the lights.

This is not acceptable so am trying to a work a solution.

My preferred is just get everything on 3 phase, but not allowed here.

My other thought was there has to be something in the market that is designed for this.
Led drivers are normally switch mode with a cap reserve. That has a voltage drop though.
I suppose transforming the voltage up, then doing something like that to drop it down again...

Anyway, does anyone have any suggestions, I am stuck with 230v bulbs and a slight V drop for up to 30s every ten minutes.

Thanks,

P

 

[netblindpaul]

You could put a soft start on the compressor, but that may not help and would be expensive.
Sounds like a bad design as you say.
What is the size of the compressor?
Is it DOL?
Even if DOL, could it be changed to Y/D and this may lower the start inrush?
Is there a starter unloading valve on the compressor?
Is this working, or is the compressor struggling to start?

 

[Marvo]

You ddn't give any indication of the load for the compressor or the lighting cct. You could try installing a small UPS that's meant for a single PC on the lighting circuit, this might be less expensive than a soft starter depending on the lighting load and it should iron out the dimming issue.

 

[johnboy6083]

didnt ever give that thought marvo, but it makes sense, its how theyre used in industry, to smooth out power fluctuation for PLC's ect, so why not on any other circuit?

Please xcan tghe OP let us know how he solves this problem? if marvos idea does work, then its one to keep in mind, for future use.

 

[Inteificio]

Sorry, I just realised how retarded my use of the word 'large' was.

Ok Lamps will be probably no more than 1kw of 230v Halogen.

I know very little on the compressor, as it is the refrigeration team that specs it.
It runs on a 16A breaker, so although larger than the original compressor (which didn't volt drop), it is still not huge.

I was considering something like a UPS, but we don't need most of the stuff in it, and especially do not need the unreliability or expense of a UPS.

Something like a transformer to pump up the voltage, a cap for tiny reserve, and an automatic auto transformer to step it back down again.

There has to be something like this on the market.

Basically brown out protection, but instead of a low voltage cut out it tops it up!

 

[Inteificio]

Has anyone tried anything like this?

APC LE1200i Line-R 1200VA Automatic Voltage Regulator.. | Ebuyer.com

 

[Knobhead]

Sort the compressor out. You can fit a “buck and boost” transformer but they take time to operate and to switch off. They are expensive just to put another nail in the coffin. By the time it switches off you’ve probably blown most of the lamps.

Star/delta is the cheap option for the compressor.

 

[Engineer54]

I think both the Electrical team and the Refrigeration team should be involved in any specification when new plant is being considered. From what your telling us here, this compressor is being called every 10 minutes, which seems excessive to me.

Do you not talk to your refrigeration team?? Your company has a problem that needs sorting out, so i would have thought everyone in the maintenance dept' would be working together to resolve this issue. So why don't you know the electrical data on this new compressor?? Have you done any testing/recording on this new installation, is it performing within the manufacturers spec etc ,etc??

Get all the information, then come back here with that information and you will get a better chance of possible solutions. At the moment, i am finding it hard to believe that a compressor that runs on a 16A circuit, can drop the voltage enough to noticeably dim the lighting in your place of work. You may have bigger issues here than at first meets the eye!!

 

[Marvo]

Have you done any testing/recording on this new installation, is it performing within the manufacturers spec etc ,etc??

Good point. Maybe go right back to basics and Z's test all the supply circuits concerned, both refrigeration and lighting. Also check if the voltage drop is occurring on the main incoming supply or just on the local circuits.

 

[netblindpaul]

Hence my raft of initial questions to try to tease out some information!

 

[Inteificio]

Sorry missed a couple of questions.

It is DOL.
Is there a starter unloading valve on the compressor? - erm, have to check what that means first ;-)
Compressor is working fine

"I think both the Electrical team and the Refrigeration team should be involved in any specification when new plant is being considered" They spec what they are fitting, then we design the electrics. The issue this time was they changed their design after speccing, or we would be 3 phase on this.


Maybe go right back to basics and Z's test all the supply circuits concerned, both refrigeration and lighting. Also check if the voltage drop is occurring on the main incoming supply or just on the local circuits.
The only noticeable dim is on those halogens, so drop is occurring at the submain. So compressor, lights and a few sockets. We have some major plant in the factory, only an issue on the stuff on this submain.

I do not think I know much about what causes volt drop, why would some lights dim from a compressor, but when the 23kw laser in the same room turns on there is not an issue!?
Is there somewhere I can be pointed to learn more about this?

p.s. thanks for your help so far.

 

[Engineer54]

Maybe go right back to basics and Z's test all the supply circuits concerned, both refrigeration and lighting. Also check if the voltage drop is occurring on the main incoming supply or just on the local circuits.
The only noticeable dim is on those halogens, so drop is occurring at the submain. So compressor, lights and a few sockets. We have some major plant in the factory, only an issue on the stuff on this submain.


Soooo, ....what does that tell you then??

 

[Inteificio]

I guess it means that the feed for the submain cannot pump enough 'trickery to maintain voltage when this&nbsp;compressor&nbsp;is running?<br><br>My assumption is that if I fatten up the cable from the main incomer the whole way through to the lights then this problem will disappear.&nbsp;<br><br>Is that assumption correct? (I must admit, I am not too familiar with how to deal with large load induced voltage drops)

 

[johnboy6083]

what size is your submain, how long is the run, and what is the total load on the submain?

 

[netblindpaul]

23kW laser probably 3ph & distributed load and on suitably designed circuit.
Compressor probably an add on where the spark adding it tied his horse up outside while he did the job!

 

[Inteificio]

Submain is probably fed off a 30m run of 6mm. Can't remember the total size, but probably a 40A or a 63A.

 

[Inteificio]

I should mention I cannot modify the system before the sub... to long to explain fully why. Short answer, this install is mobile.

So if anyone has any cunning ideas, they have to be implemented after.

 

[Engineer54]

Are you saying this installation is on a plug and socket ??

 

[Marvo]

Submain is probably fed off a 30m run of 6mm. Can't remember the total size, but probably a 40A or a 63A.

I should mention I cannot modify the system before the sub... to long to explain fully why. Short answer, this install is mobile.

So if anyone has any cunning ideas, they have to be implemented after.

The 6mm supply sounds undersized to me. If (you haven't shown any definitive test results yet) that's what's causing the volt-drop with the compressor start current and you say you can't upgrade it then your hands are tied.

We're back to the options of a UPS on the lighting circuit or a soft starter on the compressor. You previously stated these options are outside of your price budget so it looks like check mate to me. I'm all out of options that would cost less than a UPS. I did some digging around and Maplin have a selection at under 100 quid. Just a thought but if you go with a UPS this light circuit might fall under emergency lighting regs and I think there's a few requirements about this in the UK regs....

 

[Inteificio]

"Are you saying this installation is on a plug and socket ??"

Yes, a very big one.

Marvo, good point about the emergency lighting regs, didn't think of that.


So we may be stuck, shame!

looks like a last minute bodge is not going to fix this and back to drawing board.