Emerson ZB Copeland Scroll Service Manual download pdf (Page 16)

ZB Series

Installation and piping arrangement

Casing temperature

When the compressor is running, the discharge chamber including

the discharge piping is under extremely high temperature. It is to

be noted that wires and other materials that are susceptible to such

high temperature should not come in contact with these parts.

Make sure to avoid physical contact with the discharge piping and

chamber to ensure personal safety.

De-assembly of system

Caution: Before opening the system, the refrigerant has to be

released from the high-pressure side and the low-pressure side

simultaneously. Make sure that the gauge registers pressures at the

high- side and low-side as being equal to 0 (gauge pressure). Then,

the de-assembly operation may be carried out, or the compressor

can be removed by disconnecting the piping of the system.

Replacing compressor

In the case of a motor burn, the majority of contaminated oil will be

removed with the compressor. The rest of the oil is cleaned through

use of suction and liquid line filter dryers. A 100% activated alumina

suction filter drier is recommended but must be removed after 72

hours. See Application Engineering Bulletin 24-1105 for clean up

procedures and AE Bulletin 11-1297 for liquid line filter-drier

recommendations. It is highly recommended that the suction

accumulator be replaced if the system contains one. This is

because the accumulator oil return orifice or screen may be

plugged with debris or may become plugged shortly after a

compressor failure. This will result in starvation of oil to the

replacement compressor and a second failure.

Function detection of Copeland scroll compressor

The way the suction valve is closed can't be used to check the

attainable minimum suction pressure and to test the compressor

performance. This test will damage the scroll compressor. The

following diagnosis methods can be used to judge whether or not

the function of a scroll compressor is normal.

Check for supply voltage

A routine inspection of the motor winding conductivity and ground

leakage is carried out so as to determine whether or not the motor

winding itself short-circuits and the insulation-to-earth short-

circuits. If the neutral protector trips, the compressor must be

allowed to cool down completely in order to close the motor

protector.

Check evaporator fan and condenser fan operation. Connect the

gauge with the suction side and the discharge side, and switch on

the power supply. If the suction pressure is below the normal value,

it is possible that the refrigerant charge quantity is insufficient or

there is blockage in the system interior.

As far as the three-phase compressor is concerned, if the suction

pressure does not drop and the discharge pressure does not increase

to the normal value, two of the power line terminals are exchanged

to ensure that the rotation direction of the compressor is correct. If

the pressure in the compressor still fails to reach the normal value, it

is possible that the compressor has been damaged.

To test compressor discharge, the current consumption of the

compressor must be compared with the published specifications

under same operating pressure and system voltage. If the deviation

between the measured average current and the published value

exceeds ±15%, it indicates compressor damage. If the balance of the

three-phase currents exceeds 15% of the average current, it could

indicate voltage imbalance. A further inspection should be carried

out. More detailed troubleshooting procedures for compressor and

system problems can be found in chapter H of the Copeland

Electrical Handbook.

Before returning the compressor, it must be clearly established that

the compressor has been damaged. Before returning the

compressor, high-voltage tests should be carried out on motor

winding resistance and motor starting capacitor.

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Emerson ZB Copeland Scroll Service Manual Page 16

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