Relay Overload Combination - how to install?

[hybred777]

Using a ohm meter my question is how do I figure the terminals..." run, common, start on a refrigeration compressor ?" I want to install an R041 relay/overload combination or maybe another Supco relay/overload to replace the factory oem parts on failed relay-overloads. thankyou God Bless

[Yuri B.]

Hi. Honestly, "R041", "Supco relay" does not say anything to me, as I do not work with them. Do I understand rightly, the working princip on you compressor is: neutral constant, live is "on" and "off", by that, there is a capacitor wired in the scheme? (and you wish the live to go through some ovelload protection?)

[Yuri B.]

But, in any case, and I have not yet seen otherwise, common-start is more Ohms than common-run.

[Yuri B.]

By that, start-run is still more, and includes the two above resistances.

[sedgy]

if my memory is correct stat to run is twice the total of start to com
start to com =5 ohms
start to run= 10 ohms
< the numbers arejust an egzample<
can anyone confirm my memory?

[Yuri B.]

Resistance start / run is a sum of start/common + common/run. Resistance depends on the power of the motor, the more powerfull, the less (active) Ohms.

[hd88]

go to grainger or johnstone supply and pick up a 3in1 start kit for the compressor. take the model number and info off the label on the compressor and the counter sales guy or girl will give you what you need and the instuctions will help you identify the terminals on the compressor. also the compressor terminal cover has a diagrahm identifying the terminals.

[icehouse]

This is a piece I wrote for a NATE certification prep course. And most times you read left to right : C S R
FIRST:
Single phase compressor motors have a "Start Winding" and a "Run Winding" with a "Common" connection between them. Therefore the total resistance is the sum of both windings.

SECOND:
Shorted motor windingsccur when the insulation on the windings become defective and allows a shorted condition (two wires to touch), allowing a bypass of the winding. Depending on how bad of a short it is possible for the compressor to operate, but will draw excessive amps.
There should be no reading from any terminal to the compressor motor case using an ohmmeter.

THIRD:
Grounded motor windings occur when the insulation on the winding is broken down and becomes shorted to the compressor motor case.
This can be verified with an ohmmeter by touching one lead to any terminal to the compressor motor case (it is recommended to scrape away paint).

FOURTH:
A compressor motor may have a weakened winding that will short to ground when called to run. It is therefore recommended that a "Hi-Pot" tester be used in conjunction with an ohmmeter to check for insulation failure.

[icecube51]

It is therefore recommended that a "Hi-Pot" tester be used in conjunction with an ohmmeter to check for insulation failure.

Somethimes also cald a "megger" device. the device send a small current over the windings so its possible to see or to find out whitch one is sort cutted.

Ice