quinnj3
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| posted on 14/5/08 at 07:34 AM |
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3 phase power consumption (off topic)
Hi guys
I've a bit of a problem here at work I need to get a costing for the hourly run of a 3 phase plant, with all motors added together the full load
current is 75.9A, £0.05/kwh. What is the calculation?
Thanks
my aim is to build my own locost wether it takes me a week or 10 years to get started, i'm sure i will sometime
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quinnj3
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| posted on 14/5/08 at 08:00 AM |
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sorry guys just found the calculation.
it is (voltage x current x root3) / 1000 = KVA
KVA x Hours run x Unit cost = Cost
my aim is to build my own locost wether it takes me a week or 10 years to get started, i'm sure i will sometime
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smart51
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| posted on 14/5/08 at 08:36 AM |
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Motors have a high peak current when you first switch them on that drops as they get up to speed. Don't use the rated current of the plate as a
guide to running cost.
The power that a motor will consume is dependant on load. A 1kW motor can run at 1kW, basically for ever. If your load varies between 100W and 500W,
you'll never draw the full power or current.
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caber
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| posted on 14/5/08 at 09:07 AM |
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Watch out for power factor and peak load metering on industrial power supplies this can increase costs a lot!
Caber
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quinnj3
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| posted on 14/5/08 at 10:05 AM |
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I had the full load current from a motor spec sheet so was able to work out the total max current being used at any one time. The start up procedure
of the plant means that once it is up and running nothing speeds up or slows down so taking the peak into account is not neccessary. It is a waste
recycling plant which is basically a couple of converyors, magnets and trommels etc. The buyer wanted a rough price so i gave him what we think is
the worst case scenario. It worked out to be £140/week!
my aim is to build my own locost wether it takes me a week or 10 years to get started, i'm sure i will sometime
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