Mitsubishi Heavy Industries SRK25GZ-L1 Handbook page 29

(g) Cooling overload protective control
(i) Operating conditions: When the unit is operating with the outdoor unit frequency other than 0 Hz(rps) or when the
outdoor temperature sensor temperature rose beyond 41ºC for 2 minutes continuously.
(ii) Detail of operation
S SRK25GZ-L1
1) Indoor fan speed is raised forcibly by 1 step. However, the maximum speed is the 3rd speed.
2) 10A current safe operation
Taking the lower limit of control frequency at 34 Hz, if the output frequency obtained with the fuzzy calculation
reaches this value, the operation changes to the thermostat operation.
S SRK35GZ-L1
1)
10A current safe operation
S SRK502Z-L
1)
Outdoor fan speed is raised forcibly by 1 step.
2)
With the controlled lower limit speed at 20 rps, there will be thermostat operation if the output speed by fuzzy
calculation reaches this value.
3) The controlled upper limit speed control is 94 rps.
(iii) Reset conditions: When the external temperature thermistor temperature drops below 40ºC.
(h) Freezing cycle system protective control
(i) Operating conditions: When both of following conditions have continued for more than 5 minutes later than 5
minutes after the start of operation.
1) Command frequency is higher than 60 Hz(rps)
2) During cooling, dehumidifying: Indoor heat exchanger temperature - Room temperature > – 4ºC
During heating: Indoor heat exchanger temperature - Room temperature < 6ºC
(ii) Detail of operation: Changes immediately the command frequency to 0 Hz and stops the operation on the entire system.
S SRK25, 35GZ-L1
Changes immediately the command frequency to 0 Hz and stops the operation on the entire system.
S SRK502Z-L
The command speed repeats 30 minutes at 30rps ↔ 2 minutes at 62 rps. It is cancelled if outside of 1) or 2) above.
(I) Compressor overheat protection
(i) Purpose: It is designed to prevent deterioration of oil, burn of motor oil and other trouble resulting from the compres-
sor overheat.
(ii) Detail of operation
1) Frequencies are controlled with temperature detected by the thermistor mounted on the discharge pipe (Comp. dome).
(Example) Fuzzy
Inverter
Notes (1) When the discharge pipe temperature is in the range of 100 to 125ºC, the frequency is reduced by 4 Hz (4rps).
(2) When the discharge pipe temperature is raised and continues operation for 20 seconds without charging, then the fre-
quency is reduced again by 4 Hz (4rps).
(3) When the discharge pipe temperature is in the range of 95 to 100ºC, and if the inverter frequency is being maintained and
the operation has continued for more than 3 minutes at the same frequency, it returns to the normal operation.
(4) Value in ( ) indicates 50 model.
2) If the temperature of 125ºC is detected by the thermistor on the discharge pipe (Comp. dome), then the compres-
sor will stop immediately.
Simultaneously, the red LED on the printed circuit board of outdoor unit controller flashing 5 times for 0.5 second
at interval of 8 seconds.When the discharge 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.
(J) Serial signal transmission error protection
Purpose: Prevents malfunction resulting from error on the indoor ↔ outdoor signals.
(i)
(ii) Detail of operation: When the indoor unit controller ↔ outdoor unit controller signals cannot be received, the
compressor is stopped immediately. Simultaneously, the red LED on the printed circuit board of outdoor unit controller
flickers 6 time for 0.5 second at intervals of 8 seconds. Once the operation stops, it does not start any more.
(Timer lamp on the indoor unit flashing at the same time.)
After lapse of 3 min. or over
After lapse of 3 min. or over
After lapse of 3 min. or over
95
(90)
Discharge pipe temperature (˚C)
(3) 4 Hz (4rps)
(3)
4 Hz (4rps)
Lower limit
(3)
frequency 34 Hz
0 Hz (0rps)
(Cool : 22rps, Heat : 38rps)
100 125
SRK-GZ
(1), (4)
27