Agricultural Loading Issues

[dlt27]

Hi thanks in advance for any advice..
A long story, but have been asked to install new electrics to a new milking parlour on a local farm. The issue I have is that I am convinced the existing supply is not big enough, the existing supply is single phase and is installed about 30m from parlour in a top floor barn ( there are 3 x 25mm sub mains fed via 80A KMF switches( armourdes ) feeding the house, parlour and storage heaters in the house.
The problem I have is the farmer was told by a larger electrical company who installed lights in parlour (£4000 for eight low bays with 1.5 days labour which I couldn't believe, however that's another story) that the supply is large enough (apparently used clamp meter while he was milking).
The parlour installers aren't that helpful and won't give me the loading of all their new equipment ( one motor alone pulls 21A at FLC I noticed) , however I have logged the existing parlour and while milking they are averaging 65A ish ( House 10 Amps, parlour 55 Amps), but when compressor etc kicks in it can rise to 90A for short periods. Also I have noticed when milking, the lights in parlour flicker and sometimes turn off
(I have checked voltages at supply while milking and found supply drops from 230V when not milking to 217V so was thinking the ballasts were switching off due to voltage being too low, but not sure). Also could somebody correct if wrong, but was thinking this would cause motors/ capacitors etc to burn out more frequently due to the low voltage.
I keep telling farmer I think he needs new supply, however he wants me to install and check again after parlour has been Installed.
What would be really helpful is if anybody has experienced anything similar before and what would you recommend. In the ideal world I thought he should of had 3 phase supplied and 3 phase motors etc, but it's too late for that now as parlour is installed and is all single phase.
I thought maybe a new single phase to new parlour as couldn't go to where existing is as I think new parlour will still be above the 80A fuse in KMF switch.
Also I was thinking of getting a power quality analyser ( not sure if it would help though) or asking DNO too come out and check existing supply, but not sure of the procedure.
I know it's a random post ( police would consider it a cluster...k I believe) , but just looking to see how everyone else would approach this appart from not getting involved with it.
Much appreciated for any help....

 

[plugsandsparks]

Its a very common problem you describe and experience really helps over the long term.
It can be difficult to convince (with proof) that a supply is insufficient when the cost of upgrade is 5 figures.
If the client insists on fitting the new parlour first and seeing if the supply can handle it is to work out how easily and quickly you can hook in a generator to keep the farm going if supply either blows (fuse) or volts drop so low it becomes a safety issue.

 

[dlt27]

Its a very common problem you describe and experience really helps over the long term.
It can be difficult to convince (with proof) that a supply is insufficient when the cost of upgrade is 5 figures.
If the client insists on fitting the new parlour first and seeing if the supply can handle it is to work out how easily and quickly you can hook in a generator to keep the farm going if supply either blows (fuse) or volts drop so low it becomes a safety issue.

Luckily they are keeping old parlour going until change over. The generator is one that hooks up to the back of tractor and is on a 63 Mcb/ 100mA RCD. Haven’t had a lot of experience with agriculture before that’s why trying to get as much info as possible. Thanks

 

[Deleted account]

Maybe the farmer should get the previous company in for a quote. See what they say.

I think I can guess.

All you can do is, do andsay the right thing, if farmer wants to risk it it’s his risk or should I say the installers risk.

Put it in writing. Then he can decide if he wants the install done or not.

Farmers are struggling to make a living so it’s not surprising they donot relish the prospect of that extra bill.

 

[plugsandsparks]

Luckily they are keeping old parlour going until change over. The generator is one that hooks up to the back of tractor and is on a 63 Mcb/ 100mA RCD. Haven’t had a lot of experience with agriculture before that’s why trying to get as much info as possible. Thanks

Dont sweat it , farmers are well used to being at the extremes of electricity supply,, lol
If you work with him on a suck and see basis , then as long as you have solutions , then the farmer can witness the supply issues in real time, i.e. blown fuses, equipment dropping out / random behaviours due to under voltage..... (not ideal)
BUT when faced with a £70K charge from Western Power or whoever, i have managed to keep re-jigging the supply and loads to keep under the max supply. E.g LED lighting everywhere, soft start motors, PFCs, scheduling of loads to even out demand on supply etc etc

 

[dlt27]

Does anybody know if Western Power have a technical department I could speak to directly or does it all have to be done online? I would like to see if they could do assessment/ come out and then work out the best way to go forward. Thanks
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Like you said all possible, but to me poor design. Water Heaters etc already on timers so not on when milking etc
Also chillers are a big loading issue and was wondering if they could be timed or something so they don’t come on when milking, however again my worry is what if power cut or backup batteries not working and then all of a sudden comes on together and ?.

 

[PEG]

If anyone is considering things like timers,interlocks and switch-overs,you already know the answer,to the supply capacity.

I know the costs involved,in fitting out a new parlour,and you would not buy a vehicle at the same price,without having access to the fuel it needs to run

In my experience,due to the short and sporadic nature of the requirement,the cost of an increased capacity supply,and with no other similar sized power need,a generator,is the best option.

Most have this as back up,either S/A or PTO driven,as some rural supplies are prone to outage,and 200 Jerseys,look daunting from a milking stool

Who has done the feasibility study,from the parlour installers,for this expensive,capital asset?

Maybe it's same crowd,who are selling trommels and screens,to skip yards....and forgetting to mention,the space they will need,for the geny

 

[SparkySy]

I have done a reasonable amount of parlours and it all depends on how big the kit is, most of the ones I have done have been very large, some rotary ones too, these have all been on 3 phase supplies the largest was a 200a 3ph and had about 1200 milkers, huge calf facilities with heaters and all indoor housing with lighting and large cooling fans! Smallest one was 63a 3 phase that only had about 250 milkers so it is all relative. All the dairy farms I have worked on have had back up generating equipment of some description, 1200 gals needing milking twice a day would take more than the two farm hands that can operate a rotary parlour!

 

[dlt27]

He’s got 120 milkers and new milking parlour has 20 milking bays so nowhere near on the scale you’re talking about.
Funny you say, but parlour guys have said their next project is a rotary one which will milk 75 at a time.
Apparently they’ve just been trained on one in the Netherlands which will milk 5000 cows. He showed me a video of how you can even drive the thing with a battery hand drill if the drive goes down.
What I find amazing though is the guys selling it who know 10 x more than me as doing in all the time, yet they don’t advise the farmer about whether the existing supply is sufficient or if not about getting the farmer to enquire about best way to go forward with DNO etc. The farmer I am doing with doesn’t have a clue apart from the other electricians telling him supply will be fine.
Thanks again ( “ every day is a school day” )

 

[SparkySy]

I'm always amazed at how these small farms make any money from milking these days, I did a small 26 cow parlour and the farmer there said he was just about scraping a living from it, the lads there were on about the superdairys of Europe and how automated they are compared to here like you say 5000 odd milkers and very clean and tidy. One lad showed me a load of pictures of one they had done in Germany and you could of eaten your dinner off the floor mental clean!!
Most of the dairy plant Engineers and fitters I have worked with have been a great bunch, knowledgeable and helpful. Some of the Irish guys from dairymaster were the best I've ever worked with and such a laugh too!
I love that kind of work and grain storage and handling much more fun than domestic!
Good luck with your project!!
Sy

 

[farmerspark]

The parlour itself will not draw much current, the vacuum pump is basically it. The biggest loads are heating water for cleaning after and the cooling off of the milk.
Delaying cooling will present hygiene issues as milk sat at 20 plus degrees will encourage bacterial growth.
It may be possible to install an ice bank to cool water prior to milking to run through a 2 stage plate cooler to reduce the peak cooling load.

 

[Simon47]

Yes indeed, chilling will be the biggest issue. A lot of farms have gone to direct cooling which means bigger chiller (compressor) plant to directly cool the milk as it goes into the tank. As you say, a large ice bank that can be "charged" between milkings could reduce the direct chiller requirement but that's more capital to shell out. Even a plate heat exchanger run from mains water would help - but you need either a massive PHE or slow the milk flow rate down as transfer time is key to making a PHE work. A while ago I looked at controlling the pump speed to reduce the flow rate where the new PHE was basically doing SFA as the milk wasn't in it long enough to cool. Didn't get anywhere because I didn't know enough at the time and the motor was single phase - these days I'd suggest popping in a 3 phase motor and small variable drive.
IMO the two issues are going to be starting the vaccum pump and starting the compressor - both large motors, DOL starting, and with massive startup currents. Everything else in the parlour will be fairly small - but with these two I can't see any easy way to work around them.

 

[dlt27]

Had Western Power out today and said they’re pulling too much juice already without new parlour. Also first time they’ve said anything, but apparently mains fuse has burned out a few times already.
There is no solution I can see apart from 3 phase supply being put in (£££££), however they were talking whether the whole lot be run off a diesel generator?
Think I’m going to have to get some more specialist advice before going any further!!

 

[plugsandsparks]

Pure economics, i think. Cost of 140KVA TP supply = £X0000, vs Use existing supply to power lighting and all the low power items. Cost of second hand 200KVA diesel generator wired to TP board which feeds the big items used for milking. For £10000 you can get a decent used genny, thats probably around £30,000 of fuel before you get anywhere near the cost of a new supply. Its just the hassle of turning the genny on before milking... lol

 

[dlt27]

Thanks all for the advice. Will be better prepared next time.....