carrier 30gx compressor wiring question

[knight rider]

hello to everyone

got a call to a carrier water chiller model 30 gx (122)
today, reset fault (water flow , chilled water pump No 1 tripped on overload )

anyway, notice the wiring for the compressor start(carlyle screw)

we have permernant 3 phase (415v) supply to one side off the compressor windings ,WHILE the compressors is in the off state :eek:

we have TWO contactors ,one SMALL , one LARGE
the smaller contact pulls in for a few seconds then drops out and the larger one pulls in and stays in and compressor runs happy:)

now , this is not start delta as there are only 2 contactors and this is NOT part wind as the smaller contactor pulls out before the larger one pulls in

as we have permernant 3 phase supply to one side off the windings when the compressor is OFF ,
is this used as oil heating ? :confused:

does anyone have any expreience on this type off start , as i have never come across this before

ALL INFORMATION AS GREATLY WELCOMED

many thanks

[malik55]

Hi knight rider
This is a the same Wye(star)-Delta motors, only difference is it works with 2 contactor as you mentioned, u1-v1-w1 connected through contactors Y and delta, the other side of windings w2-u2-v2 are connected continuously with power, it works same as older Y-d controls, first Y contactor comes on and as other side is connected with power, motor comes on ,after time delay Y contactor goes off and D contactor comes on and motor goes at full current, in this way they saved one contactor..... NOTHING TO DO WITH OIL HEATING, Oil for these chillers is stored in the oil tank and not in the compressor.
malik55

[knight rider]

hi malik55

thank you for your explanation , yes that sounds straight foward enough to understand ,

off course the oil heating is done via a pad heater on the oil seperator and a trace heater on the oil line leaving the oil seperator to the compressor

are there any advantages off this setup ,other then the saving off a contactor

many thanks

[malik55]

Hi knight rider
I don't think there is any thing else, may be some one from carrier Design section can answer if it is there.....:rolleyes:
malik55

[venkatesh]

Hai iam venkatesh:D,
I require to have the user manual of the air cooler 30GX screw chiller.
Please help in getting it.

[nike123]

Hai iam venkatesh:D,
I require to have the user manual of the air cooler 30GX screw chiller.
Please help in getting it.
http://eto.carrier.com/lit.asp

[GHAZ]

Hi knight rider i,ve rebuilt these o6n carrier screw compressors and change the windings on them and they are definetly star delta motors and to run a star delta winding. in star delta configuration you have to make a star point,if there is live phases on compressor and no star point connection then the compressor wont do any thing and the windings wont get damaged and it will sit there perfectly. and then delta with three contactors ,BUT with carrier 06na screw compressors the line is always energised which( eliminates the line contactor) and the smaller contactor is the star point one and then the larger contactor is the delta contactor which pulls in after a few seconds and smaller star point contactor drops out, and also in the chiller it has reverse rotation sensing device which works by sensing the motor internal wiring connection and the live external phases before the compressor starts and tells you either swap the phases around or its ok to run,a safety device. hope this explanation is understandable

[knight rider]

thank you ghaz for your reply and excellent explanation ,
i was curious why only 2 contactors unstead off three ,
once again thanks

[rizwan]

i have a compressor toyo carrier serial no1192w02058 his motor has flash i need winding conaction double star