Increasing 3PH Supply?

[-Matt]

A company i do work for are running over the capacity of their existing 100A 3PH supply, they are pulling around 100-120A all day long.

I am trying to get them to get a bigger supply, they have tried asking for a 250A supply from the DNO, but they want £20K. (they reckon the transformer would need upgrading)

Its an overhead supply, and a transformer (pole mounted) is only 15-20 metres away, on boundary of customer property.

I don't know what size the transformer is, but its not the smallest I've ever seen, and only looks to supply 2 properties.

Ive just had the thought of a second 100A supply, as it would be dead easy to split the demand across two supplies.

Has anyone tried getting an additional 3PH supply? and was it more cost effective than a 250A supply?

I guess it still comes down to if the transformer has capacity, but i find it hard to believe it would be maxed out with 2 properties?

Cheers

 

[Pete999]

A company i do work for are running over the capacity of their existing 100A 3PH supply, they are pulling around 100-120A all day long.

I am trying to get them to get a bigger supply, they have tried asking for a 250A supply from the DNO, but they want £20K. (they reckon the transformer would need upgrading)

Its an overhead supply, and a transformer (pole mounted) is only 15-20 metres away, on boundary of customer property.

I don't know what size the transformer is, but its not the smallest I've ever seen, and only looks to supply 2 properties.

Ive just had the thought of a second 100A supply, as it would be dead easy to split the demand across two supplies.

Has anyone tried getting an additional 3PH supply? and was it more cost effective than a 250A supply?

I guess it still comes down to if the transformer has capacity, but i find it hard to believe it would be maxed out with 2 properties?

Cheers

Is the 120Amp just limited to 1 phase or are all 3 phases affected in the same way?

 

[-Matt]

Is the 120Amp just limited to 1 phase or are all 3 phases affected in the same way?

Its mostly 3Ph (no neutral) equipment, so all 3 phases, but well balanced.

 

[Pete999]

Its mostly 3Ph (no neutral) equipment, so all 3 phases, but well balanced.

 

[westward10]

Is this 100-120A loading constant.

 

[Deleted member 105166]

When we enquired about getting a 100a 3-phase supply a couple of years ago, SSE quoted a good price - around £1,700 - but it was conditional on surrendering two separate 100a singles that we have.

 

[The Ghost]

Presumably the equipment is motor equipment? Is the equipment rating in total matching the amount being pulled. I suppose you are using a clamp meter? Is there signs of thermal damage?

 

[davesparks]

Have you asked them what size supply it would be possible to get without an upgrade of the transformer?

Is there a planned increase in the current load, as you’ve requested a supply just over twice the current demand I assume there must be?

They almost certainly won’t give you a second supply in to the same installation, especially not such small supplies.

 

[davesparks]

How has the demand been measured, by instantaneous readings with a clamp meter or by a load study over a period of time?

 

[Deleted member 105166]

A cost effective option may be to request an additional 100A single phase supply and separate some/all of the SP loads off the TP board, to bring its load down under 100A. Assuming the DNO will allow you the additional SP supply, of course.

 

[Andy-1960]

What is the power factor, you may be able to reduce the current being drawn by installing some power factor correction equipment.

 

[dmxtothemax]

Have you asked DNO how much more you can safely pull from the existing transfomer ? You may be able to go to say 150A, that would be a simpler cheaper option.

 

[marconi]

Prompted by davesparks good idea of a load study, could you tell us please what major equipments are responsible for the lion's share of the load current and whether they are on all the time or scheduled? I am wondering whether the client might be interested in an energy audit to see if he can achieve the same business outputs using less energy (load current) either by changing the way the equipments are used or controlled or by investing in new equipments or sub-systems of them. After all 415 x 1.73 x 120 = 86kW so 86 x 8 hr working day = 688kWh or 86 x 24hr(all day long) = 2064kWh.

688 x 13p/kWh costs £90 a day(£33k) and 2064kWh costs £270 a day(£99k). (Figures in brackets over 365 days)

If say 10% could be saved in energy that's £3k a year or £10k a year reduction in cost for 8hr or 24 hr usage respectively

Updating air compressors, process heating, HVAC, refrigeration plant and lighting (or their control) are candidates for 'spend to save'. I have no experience of the magnitude of typical savings but 10% does not seem unrealistic to me.

Just some thoughts to go in the melting pot on a different approach to spending £20k and achieve the same end.

 

[bigspark17]

In my experience the DNO will not put 2 seperate supplies into same buildng, especially a small one.
Why not upgrade to 150/160A amp this may be surprisingly affordable compared to the 20k 250A supply

 

[plugsandsparks]

I have been managing a 80amp TP supply, as the DNO want £55K to upgrade !!!.

The ideas already suggested have worked so far, these are.
1. LED lighting throughout, thats low bays, security and office.
2. PFC (didn't offer much, but i know some other installations can benefit substantially, so worth a visit.
3. Gas supply was easy to upgrade so all electric hot water and electric heating was removed, new combi installed to supply hot water throughout.
4. 3 X ammeters installed so manager can keep an eye on it and manage machines in sequence so to smooth out peaks.
5. Most machines have VSD which has a huge impact on start currents.

So far, clients supply hovers around 80 but now rarely goes over, often it is much less.
Hope this helps

 

[marconi]

I really liked plugsandsparks ideas and installing ammeters to allow some management of equipment is likely to be simple and effective - but probably not the complete solution. I thought though that maximum demand ammeters might be better which read actual current and integrated over time (rolling 15 minute interval) current being drawn. See:

Eltime - Maximum Demand Meters - http://www.eltime.co.uk/product.php/8/Maximum%20Demand%20Meters.html

 

[marconi]

I really liked plugsandsparks ideas and installing ammeters to allow some management of equipment is likely to be simple and effective - but maybe not the complete solution. I thought that maximum demand ammeters might be more helpful which display actual current and averaged current over a rolling 15 minute interval. See:

Eltime - Maximum Demand Meters - http://www.eltime.co.uk/product.php/8/Maximum%20Demand%20Meters.html

This was one has an alarm signal output:

Max. demand ammeter BRL-110CH : Daiichi Electronics Corporation - http://www.daiichi-ele.co.jp/en/product/product_0035.html

 

[-Matt]

Thanks Guys, Sorry about delay coming back, all been a bit busy!!!

Yes i would say from what I've measured with a clamp they are drawing around 100-120A/PH most of the day during business hours.
Each phase is almost exactly the same, as its 90% 3PH equipment (no neutral).

I have tried suggesting not using everything all at once, but this effects their production rate...

The biggest offender is a 25KW 3PH motor which runs all day, it does spike as a matter of operation, it uses a constant 35A/PH then around every 15 seconds it spikes up to around 65A for a couple of seconds.
It runs some heavy duty hydraulics.

Then there are around 15/20 smallish 3PH motors (around 1KW Each).

So all added up, its a fair amount of power being used, however they are yet to blow a service fuse.


I did have one thought while i was there earlier on another matter, they have an office around 30 Meters away which has its own 100A 3PH supply (separate meter), i would be amazed if they use 20A/phase in the office.
So there looks to be the potential to say run a 60/80A submain from here to the workshop, then take some load off the workshop supply.

This is not something i have done before and feels bit of a "bodge", and need to look at any regulations this would go against ( 2 supplies in one building). But it would certainly help with the overloading.

 

[westward10]

Is this 100-120A constant or occasional.

 

[marconi]

Re #18
The biggest offender is a 25KW 3PH motor which runs all day, it does spike as a matter of operation, it uses a constant 35A/PH then around every 15 seconds it spikes up to around 65A for a couple of seconds. It runs some heavy duty hydraulics.

The average line current of this motor is:

Iav = (65 x 4 x 2) + (35 x [60-8]) all divided by 60 = [520 + 1820] / 60 = 39A