Compressor help

[Danny11]

Hi guys

I was just woundering how other engineers go about checking a compressor to see if it gone down.
Im talking anything from a 2.5 to 10.5 kg.
VRV.VRF types


If you have time a step by step guid would be great.

Cheers

[Daikin=Overated]

In a word. Megga.

Hand wind type I find easier to work with and more easy to interprit, but I do use both.

I find that in 95% of compressor electrical issues (when down to earth) it'll blow the MCB. It's usually that clear. If 3PH, then check the amperage across each phase to begin with.

If blowing the MCB, I go to CU and fault find from there to indetify through process of illimination as to which component is at fault.

What circumstances do you have with the compressor in particular, are you sure it's not a compression issue??

J.

[The Viking]

Before you start turn the isolator OFF
Then, and only then:

1. REMOVE THE CABLES FROM ALL COMPRESSOR TERMINALS.

2. Check that all cables are removed.

3. Using an Ohm meter, measure the resistance between the terminals.
On a single phase pot the resistance between T1 and T2 + the resistance T2 to T3 should add up to the resistance of T1 to T3.
On a 3 phase compressor all the resistances should be within 10% of eachother. (There are exceptions, like part wind/star-delta set ups).

4. Using a Mega Ohm meter (normally referred to as a MEGGER but this is a TM, a bit like HOOVER), check for resistance between the terminals and earth. This should be open circuit.

5. Carry out a dry run of the controls without the compressor connected, checking for correct voltages to the compressor and function of delay timers. This is especially important on inverted units, as the voltages coming from the inverter MUST BE EQUAL to each other (each phase measured to neutral). If they not are equal, there is a problem with the inverter and the compressor might as a result suffer damage.

If all the above checks out OK, then you are good to start the compressor. Just remember to have an Amp meter clamped on to it and be prepared to turn it off quickly if it doesn't sound right.