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Thread: Running Costs
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08-04-2007, 07:34 PM #1
Running Costs
I need help with the following please
I have to advise customer running costs between the following:
12 Kw Mitsubishi FD 501 DT Cassette system, Inverter , running amps are 17 amps
or 12 Kw Mitsubishi FD 501 Cassette system 3 Phase . manual says running amps are 7 amps, I presume thats 7 amps per phase
Kindly advise
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08-04-2007, 08:38 PM #2
Re: Running Costs
Well 3 phase tends to have better torque chararistics and and such and les start surge, and tend not to have such a voltage sag on start up, All in all the 3phase is best bet.
As for details to many veriables with to little data to plug into them.
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08-04-2007, 09:24 PM #3
Re: Running Costs
Hi Abe
To evalute running costs you have to convert the running amps to Kwh (kilowatthours) - the basis for how electricity is costed.
To convert you need to multiply the running amps x voltage x running hours .
So, for your single phase unit it would be:
17 (A) x 230 (Volts) x ? (hours per year) x cost of electricity
and for the 3 phase unit it would be:
7 (A) x 720 (volts) x ? (hours per year) x cost of electricity
The cost of electricity can be found from the customers last bill. The total running hours can be estimated from his intended use (hours per day x days per week x weeks per year)
From the running amps you stated, it will be more expensive for the 3 phase unit.Last edited by frank; 08-04-2007 at 09:27 PM.
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08-04-2007, 10:32 PM #4
Re: Running Costs
MG Pony, the 3 phase will ahve a bigger starting torque because its a non inverter.
The first one is an inverter on 240 VAC and will not have a starting torque at all.
The overall cost for the inverter will be smaller but what is also very important is the comfort, how you feel the cold draft. Far less with an inverte because they increase evaporating temperature if possible.
And this better comfort is something you can't calculate.It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.
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09-04-2007, 12:58 AM #5
Re: Running Costs
Thank you Pny Frank and Peter
Actually , the customer is less concerned about running costs, I have the choice of fitting either a 3 phase system or the new inverter.
The inverter is only about a hundred pounds more dearer, but I was after a system which is smoother and more reliable..
I am placing the order on Tuesday, I think Im going for the Inverter system
Thank you