A1
motor protection module (INT69SCY)
B1 room
thermostat
F1 fuse
F3 high-pressure
switch
F4 low-pressure
switch
K1 contactor
R2 crankcase
heater
S1 auxiliary
switch
Y5
Solenoid valve for vapour injection
Figure 7: Control Circuit
18 Electronic Motor Protection
Protector Specifications :
Type:
Carel
Voltage:
24 V AC; 230 V AC,120/240 V AC
Control Rating:
60 VA, 25 A Inrush 300/375 VA 25/15 A Inrush
Normal PTC resistance: 250 to 1000 Ohms
Trip resistance:
>4500 Ohm +/- 20%
Reset resistance:
<2750 Ohms
Module time out:
30 m/- 5 minutes
Low Voltage Sensing: None
Phase Monitor:
No
Fig. 8: Thermistor Resistance Curve
The electronic motor protection system as used in all ZH56K4E ... ZH11ME models is identified by a “W” as the
center letter in the motor code. This system utilises the temperature dependent resistance of thermistors (also called
PTC resistances) to read the winding temperature. A chain of four thermistors connected in series is embedded in the
motor windings so that the temperature of the thermistors can follow the winding temperature with little inertia. An
electronic module is required to process the resistance values and trip a control relay depending on the thermistor
resistance. The characteristic gradient of a thermistor resistance curve is shown in Figure 8. The resistance curve can
be designed for different operating points, the nominal response temperature (NAT), e.g. 80 °C, 130 °C, 140 °C and
must comply with the tolerances laid out in the standard DIN 44081.
Module
L1/T1 neutral connection
L2/T2 line voltage connection
S1, S2 thermistor chain connection
M1, M2 control circuit connection
Figure 9: Wiring of the Motor Protection Module
For protection in case of blocked rotor one thermistor for each phase is embedded in the winding heads on the upper
(suction gas) side of the compressor motor (NAT 100 °C). A fourth thermistor is located in a winding head at the lower
end of the motor (NAT 140 °C). A fifth sensor is located in the discharge port of the fixed scroll to control discharge
gas superheat (NAT 140 °C).
C6.2.16/1004/E 7
