Compressor Draws More Power

[Mohammed Qasim]

Hi
Many times I faced the same problem but I havent got
an accurate answer .It relates with a rotary or piston compressor
that draws more than the required power till its internal
overload opens ,I know that a defective capacitor could lead to this but I am talking when the capacitor is
not defective and the condenser is clean also the fan is
working properly ,most of technicans consider it a coil
problem an I agree with them ,hence when checking the
coil for ground how much the reading should be ?Personally I reached above 40 MOhm and no ground ,other than that I have to assume a small contact between the start an running coils.The last assumption is a refrigerant contamination .



Please anyone have more about that I will be thankful


Here are some information about the case:
- The unit is R22 ( although I experienced the same problem with R 12 and R 134 a ).
- For R22 suction presure is 55-60 psi and the outdoor temp. is 80 F .Indoor entering dry bulb temp
is 82 F.
- The unit starts normaly but after about 10-15 min. the amperage begins to rise gradually until
the internal overload opens.
- No earth between the terminals and the body exists below 40 Mohm.

* For me the 2 Mohm is very small and any compressor that have such resistance as an earth
will not work properly .

-

[Tesla]

Hi Mohammed
Anything above 2Mohm is ok. A couple of other things to check is resistance from compressor terminal of neutral and the earth. Check the basics when comp is running superheat and subcooling and comp temp and current. You could use a direct online tester if you think the start gear is defective.
Good luck

[Magoo]

In Libya, you would have to suffer from high condensing temperatures given the summer conditions.
Can you tell us the operating pressures.
magoo

[Tesla]

;)
Hi Mohammed
Anything above 2Mohm is ok. A couple of other things to check is resistance from compressor terminal of neutral and the earth. Check the basics when comp is running superheat and subcooling and comp temp and current. You could use a direct online tester if you think the start gear is defective.
Good luckSorry I was told to write ten characters so here they are

[Entropie]

The required motor power from a compressor depends on the refrigerant mass flow multiplied by the enthalpy difference of the (polytropic) compression (enthalpie@discharge-enthalpie@suction). For different refrigerants and applications different motor power is required. Manufacturers take this into account when produceing a compressor for freezers or air conditioning. Air conditioning compressors do have stronger motors, R22 compressors do have stronger motors then those for 134a. Whenever you use a 134a compressor on R22 or a freezer compressor in an air conditioning application it is likely that the motor is overloaded and hence trips at a point. The full compressor designation on the nameplate gives you the information what type of compressor you have.

[D.D.KORANNE]

Check design conditions v/s operating conditions.