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UNKNOWN MOTOR STARTING /WIRING HELP


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#1 ged

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Posted 13 December 2005 - 02:13 PM

have been asked to wire a Copeland D4RH COMPRESSOR

I have not seen it yet but have have the following information

380 - 420 volts
178 - 192 amps

I called copeland and was given the following information. The motor starts using 2 of the 3 windings for not more than 1 second ? (this seems very short to get up to speed)

then a single winding runs the machine.

I was told the maximum operating current was 44.5Amps
The LRA was 177A
Inrush Current was 133A

I apologise for the lack of info but can anyone proffer some advice wrt starting cable sizes fuse /mcb size ?

Without seeing anymore info I was assuming the following

Protect with a Type D 63A MCB/MCCB
Wire with cabling to suit above into 2 x contactors with a timer to energise first winding 1 & 2 DOL ?

Then after time out contactors change over to energise winding 3

Does anyone know of any pre manufactured starters of this type ?

If the main board only has a 200A incomer am I sailing too close to the wind ?

Thanks for any advice in advance

#2 jraef

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Posted 13 December 2005 - 04:14 PM

That does not sound right. Single phasing a motor will not reduce the current on the 2 phases connected, only on maybe the average curent. So in effect you may be able to fool an averaging meter of some sort, but I have never heard of anything so ridiculous. That said, I have been proven wrong before ...

More likely, you got connected to someone who did not truly understand how a "Part Winding" starter works. What that scheme does is to connect part or each of the 3 phase windings, as in 58% (I think), then after a few seconds another contactor adds in the rest of the windings. It is still all 3 phases, but the motor has the winding split and brought out to terminal blocks in the connection box. There are plenty of starter manufacturers who make Part Winding starters, and it is a very common way to start ompressor motors. Do a google search on "Part Winding Motor Starter" and take a look at some wiring diagrams. Then contact Copeland again and ask if this is what they recommend.
"He's not dead, he's just pinin' for the fjords!"

#3 ged

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Posted 14 December 2005 - 08:37 AM

Thank you for your advice




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