Mitsubishi Electric EHGT17D-YM9ED Service Manual page 57

Booster heater
Thermostat (90°C) and thermal cut out (121°C)
121 °C
Thermal
cut-out
9
3 + 6 kW heater (400 V, 3 phase)
1kW
1 2
Earth leakage circuit breaker for heater
Relay for heater
R S T
U V W
OCH722A
Part Name
90 °C
Manual reset
water
thermostat
10
1kW
2kW
1kW 2kW 2kW
3
4 5 6
A1 A2
Measure the resistance between the terminals with a tester.
Terminal
9–10
Terminal
1−2=2-3=1−3 105.8(+11.8/−5) Ω
4−5=5-6=4−6 52.9(+5.8/−2.5) Ω
If a short circuit occurs on the booster heater, immersion heater, or each power
line, a short-circuit breaker will trip and power source will be blocked.
Eliminate the causes of short circuit and then turn on the breaker again.
When the applied voltage is not 230 V AC across the terminals A1-A2, check
the terminals R-U, S-V, and T-W are open.
When the applied voltage is 230 V AC across the terminals A1-A2, check the
terminals R-U, S-V, and T-W are short.
57
Checkpoints
Normal Abnormal
110(±35) mΩ Open or Short
Normal Abnormal
Open or Short
Open or Short