Mitsubishi Heavy Industries FDT90VNPWVH Service Manual page 46

(ii) If the temperature of 115ºC is detected by the sensor on the discharge pipe, then the compressor will stop im-
mediately.When the discharge pipe temperature drops and the time delay of 3 minutes is over, the unit starts
again within 1 hour but there is no start at the third time.
(12) Current safe
(a) Purpose
Current is controlled not to exceed the upper limit of the setting operation current.
(b) Detail of operation
(i) Input current to the converter is monitored with the current sensor fixed on the printed circuit board of the outdoor unit
and, if the operation current value reaches the limiting current value, the compressor speed is reduced.
(ii) If the mechanism is actuated when the compressor speed is less than 30 rps, the compressor is stopped immediately.
Operation starts again after a delay time of 3 minutes.
(13) Current cut
(a) Purpose
Inverter is protected from overcurrent.
(b) Detail of operation
Output current from the inverter is monitored with a shunt resistor and, if the current exceeds the setting value, the
compressor is stopped immediately. Operation starts again after a delay time of 3 minutes.
(14) Outdoor unit failure
This is a function for determining when there is trouble with the outdoor unit during air-conditioning.
The compressor is stopped if any one of the following in item (a), (b) is satisfied. Once the unit is stopped by this function, it
is not restarted.
(a) When the input current is measured at 1 A or less for 3 continuous minutes or more.
(b) If the outdoor unit sends a 0 rps signal to the indoor unit 3 times or more within 20 minutes of the power being turned on.
(15) Serial signal transmission error protection
(a) Purpose
Prevents malfunction resulting from error on the indoor ↔ outdoor signals.
(b) Detail of operation
(i) If the compressor is operating and a serial signal cannot be received from the indoor control with outdoor control
having serial signals continues for 7 minutes and 35 seconds, the compressor is stopped.
(ii) After the compressor has been stopped, it will be restarted after the compressor start delay if a serial signal can be
received again from the indoor control.
(16) Rotor lock
If the motor for the compressor does not turn after it has been started, it is determined that a compressor lock has occurred
and the compressor is stopped.
(17) Refrigeration cycle system protection
(a) Starting conditions
(i) When 5 (Heating: 9) minutes have elapsed after the compressor ON or the completion of the defrost control.
(ii) Other than the defrost control.
(iii) When, after satisfying the conditions of (i) and (ii) above, the compressor speed, indoor air temperature (Thi-A)
and indoor heat exchanger temperature (Thi-R) have satisfied the conditions in the following table for 5 minutes:
Operation mode
Cooling
Heating
(b) Contents of control
(i) When the conditions of (a) above are satisfied, the compressor stops.
(ii) Error stop occurs when the compressor has stopped 3 times within 60 minutes.
(c) Reset condition
When the compressor has been turned OFF
Compressor speed (N)
< =
40 N
40 N : Outdoor air temperature 0°C < = > =
60 N : Outdoor air temperature 0°C < =
>
45
- -
Indoor air temperature (Thi-A)/
Indoor air temperature (Thi-A)
Indoor heat exchanger temperature (Thi-R)
10 Thi-A 40 < = < =
0 Thi-A 40 < = < =
'19 • PAC-SM-334
Thi-A−4<Thi-R
Thi-R<Thi-A+6