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21
Vol. 1.2 © 2020 Hanbell Precise Machinery Co., Ltd.
All rights reserved
4. MOTOR
4.1 Motor cooling
There are two ways to cool the magnetic centrifugal compressor. They are by cooling the motor stator,
and by cooling the motor rotor and magnetic bearing. For the motor stator cooling, it is by
high-pressured liquid refrigerant coming from the condenser. The inlet and outlet positions are shown
as the "Motor cooling inlet (liquid)" and the "Motor cooling outlet" below. For the cooling on the
motor rotor and the magnetic bearing, it is mainly by the medium-pressured gas coming from the
economizer. The inlet and outlet positions are shown as the "Bearing cooling inlet ( gas)" and
"Bearing cooling outlet" as below. It should be noted that when the shaft length’s elongation and
bearing’s temperature is in alarm value (see Chapter 4.3 for alarm values), we can turn on the auxiliary
liquid refrigerant (from the condenser) to mix with the medium-pressured gas to cool the magnetic
bearing or motor rotor (as the 4.4 pipeline diagram). At the same time, opening the "Auxiliary outlet of
the bearing cooling" can prevent refrigerant be fluid.
Figure 4.1
Motor & Bearing Cooling
4.1.1 Heater
One 300W UL approved heater has been installed in every compressor as a standard accessory. The
function of the heater is to prevent condensation of refrigerant inside compressor. Before restart of
compressor after shutdown for a long time, please turn on heater at least 24 hours.
Figure 4.2 Heater
Spec.
:
300W; 110V or 220V; IP 54; UL certified
Note: If compressor is installed in low ambient temperature, please turn on the heater once compressor
stop running.
4.1.2 Pt100 RTD (Resistance Temperature Detector)
Recommended max. measurement current DC 1 ~ 3mA for heat coefficient <0.1
℃
Heating coefficient: 10m
Ω
/K
Sensor resistance at 0
℃
: 100
Ω
±0.12
Ω
Change of resistance 0 ~ 100
℃
: 0.385
Ω
/K
Insulation test voltage (V): AC 1.5kV
Motor Cooling Inlet (liquid)
Motor Cooling Inlet (liquid)
Motor Cooling Inlet (liquid)
Motor Cooling Inlet (liquid)
Bea
Bea
Bea
Bearing Cooling Inlet
ring Cooling Inlet
ring Cooling Inlet
ring Cooling Inlet
(gas+liquid)
(gas+liquid)
(gas+liquid)
(gas+liquid)
Motor Cooling Outlet
Motor Cooling Outlet
Motor Cooling Outlet
Motor Cooling Outlet
Auxiliary
Auxiliary
Auxiliary
Auxiliary
B
BB
Bearing Cooling Outlet
earing Cooling Outlet
earing Cooling Outlet
earing Cooling Outlet
Bearing Cooling Outlet
Bearing Cooling Outlet
Bearing Cooling Outlet
Bearing Cooling Outlet