Part Winding and Star Delta Motors

Hello,

probably i may not frame the questions in right way, as my knowledge is limited on electrical motors. but still i do my best...

what are the different type of motors? Part Winding Motor/Star-Delta Motor/any other??

Why different motors are used (PW/Star Delta)?

Which one is widely used in supermarket refrigeration in europe?

what is the difference between part winding and star delta motors?

i am bit confused, whether connections in terminal box makes the difference in different motors (PW/Star Delta) or is it motor winding?

Thanks

For your homework it's best to use Google..At least you can be seen as active rather than waiting here for answers..

Good luck.

The starting technique depends on the motor size and application.

The most common motor is the Squirrel cage type. It can be started direct, star, delta or star\delta.
The most common starting technique is direct connection, star or delta.

You can find a lot of info on Danfoss web site.

There are others, for single phase motors, like CSR, CSCR, and variants with voltmetric or ammetric relay.

star delta have 3 contactors to start it,part wind have 2 contactors which kick in with 0.5sec delay

Also part wind have 12 motor leads where a normal star/delta has 6

Quote:

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Originally Posted by Quality

Also part wind have 12 motor leads where a normal star/delta has 6

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Are you sure?

I am sure a part wind motor is simply 2 separate motor windings on the same stator usualy 50/50 but I have seen 60/40

Quote:

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Originally Posted by Quality

I am sure a part wind motor is simply 2 separate motor windings on the same stator usualy 50/50 but I have seen 60/40

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And each motor has three leads (direct start on 50% of the winding), 6 in total

I was refering to a winding have 2 leads hence 6 per motor

HI trane recipes used to have 12 leads because they were dual volt p/winds, copeland do a 50/50, 6 pins ,66/33, 6 pins with star point connection and newer version of 60/40 with 6 pins with double delta connection were all the winding coils are joined together which is a better winding because it generates less heat , you will find most large semi hermetic screws which are 50/50% ,6 pins have p/wind motors are double delta connection, i.e refcomps, bitzers

The Bitzer was my reference

What about a closed transition star delta contactor arrangement with four contactors, elliminates the transitional spikes. Expensive so concider a soft starter with parallel line contactor.
The transitional spikes generally kill motor windings using star delta, dependent on phase relationship cross over.

this should wind everyone up. Its called vector shift between phases.

Even with part winding you can use soft start. All you need to do is to connect the the two windings together.
proper bridges are supplied with every part winding compressor.

Quote:

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Originally Posted by Magoo

What about a closed transition star delta contactor arrangement with four contactors, elliminates the transitional spikes. Expensive so concider a soft starter with parallel line contactor.
The transitional spikes generally kill motor windings using star delta, dependent on phase relationship cross over.

this should wind everyone up. Its called vector shift between phases.

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I certainly wish this had been incorporated into a couple of Cold Stores I worked on in the past - would have saved many motor rewinds - managers get a very glazed look in their eyes when you mention vector shift. ;)

Was the same on a mixer I took over, it had, amongst it's many faults, been wired delta-star. Replaced the whole lot of control gear ( aside from a timer) with a soft starter, added a lot better interlock to it and enclosed it in a sealed cabinet. Stopped the minor issue of the mountings pulling loose from the floor every so often, and I was able to replace the supply breaker with a saner rated one. Adjusted the soft starter to give it's longest run up time, made for a smooth start irrespective of load.

1) part winding 60:40 or 66:33 motors are used in european supermarkets for compressor motors above 7.5 kw . these motors can be started up without the use of compressor unloading mechanism ... example a start unloader like suction discharge by pass line .
2) 66:33 motors are better than 50:50 as these can take start up loads better . First 66% winding is switched on and within one second the balance 33% winding comes on via timer . This sort of start up also helps restrict the start current kick since only one winding ( part winding ) is put across the power . Both can be interlocked , that means if one winding trips , both windings should switch off to avoid motor operating on part winding .
3) Caution : do not switch on smaller part winding first . INDIVIDUAL WINDINGS NEED INDEPEDENT OVERLOAD RELAYS OF DISCREET RATING
4) Star delta motors start with 30% of power whereby compressors must be switched on with 100% unloaded start .