UNKNOWN MOTOR STARTING /WIRING HELP

[ged]

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

[jraef]

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.

[ged]

Thank you for your advice