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....

 

[Simon47]

Will have to be a fairly hefty genny to start the big motors.
The biggest issue I see with using a genny is how to deal with the chiller plant - that's not something that can be just turned off at the end of milking. You might need to look into having two compressors - a large one to use during milking (especially if direct cooling), and a smaller one that can run on the mains supply for in between.
I've worked on farms where there's a tractor driven vacuum pump - either for emergencies, or for off-grid milking out in the fields. If you could get load down enough to run the chiller off the mains (and use an ice bank for "cold" storage), then it might be sufficient to just run the vacuum pump from an engine. Or, belt drive both the vacuum pump and a genny from one engine - so you don't need quite so big a genny.

 

[dlt27]

Unfortunately I am mainly an install electrician so don’t have much experience with motors etc etc. I know the basics, with dol and capacitor start/ run and the like but not much more than that. I believe they’ve got a plate cooler with the milk and apparently the guys who fitted the tanks have said they can use a relay so when vac pumps turn on compressors won’t run.
I have covered my arse now as everybody is aware of loading issues and western power have said they need 3 phase, however farmer seems to want to bury his head in the sand and is adamant it will be too expensive and will try everything just to make work. To me using relays, timers etc still isn’t going to solve issues with low voltage etc, however from experience I will make sure everything is in writing and signed by him.
“ If only guys selling parlour would have advised him about checking supply was adequate before building, installing etc”
Thanks again for all the valuable advice..