Mitsubishi Heavy Industries FDT28KXE6A Service Manual page 14

4) When the under-dome temperature (detected by Tho-C) exceeds 20°C and the under-dome superheat is 15degC, the
compressor protective start control "A" is cancelled and the inverter frequency will be increased by 5Hz per 25 seconds.
(d) Compressor protective start control "B" according to the crankcase heater ON time (Master unit/Slave
unit)
If it is the 1st startup after the cumulative crankcase heater ON time has elapsed less than 45 minutes since power ON
1) After 4-way valve switching safeguard, inverter frequency is set at 20Hz. And during reducing frequency to 20Hz
after 4-way valve switching safeguard, if the time for reaching to 20Hz is elasped 1 minutes after startup, it is set at
the maximum frequency after 1 minute elasped (20Hz).
2) During the period of 18 minutes after the inverter frequency reaches to 10Hz (the frequency to complete startup op-
eration), the maximum inverter frequency will be increased from 20Hz by 5Hz per 2 minute.
3) From 18 minutes to 24 minutes after startup, the maximum inverter frequency will be increased by 5Hz per 1 minute,
and this control will end when 24 minutes is elapsed after startup.
4) After this control ends once, if it is the 2nd startup or the period of 45 minutes after th power ON is elapsed, this con-
trol will be shifted to the compressor protective start control "A".
5) If the compressor stops within 24 minutes after startup, and when the compressor starts again, the compressor protective
start control "B" is performed during the cumlative period of 24 minutes after the initial startup. However when the period
of 45 minutes has elapsed since compressor stopped, the control is shifted to the compressor protective start control "A".
6) When the under-dome temperature (detected by Tho-C) exceeds 20°C and the under-dome superheat is 15degC, the
compressor protective start control "B" is cancelled and the inverter frequency will be increased by 5Hz per 25 sec-
onds.
(4) Solenoid valve (SV6,7) control for oil return from oil separator (Maste unit/Slave unit)
(a) When the compressor starts, the following solenoid valve for corresponding compressor is opened respectively.
Compressor
CM1
CM2
(b) SV6, SV7 is kept open for the period of 3 minutes after 4-way valve switching safeguard control and compressor protective
control start.
(c) If the compressor frequency is 80Hz (68Hz) or higher, SV6,7 opens, and if the compressor frequency is 76Hz(64Hz) or
lower, it closes.
Note (1) Value in ( ) are for the models FDC615, 680KXE6 and FDC1180~1360KXE6
(d) If the compressor stops after SV6, 7 opens, SV6, 7 remains open for 3 minutes and 10 seconds, then closes.
Solenoid valve
(SV6, 7)
Compressor
Solenoid valve
SV6
SV7
SV6, 7 open
SV6, 7 closed
76Hz
(64Hz)
Actual compressor frequency (Hz)
OFF
20Hz
Stop
15 sec.
3 minutes
Compressor
Run
Starts
command
12
-
80Hz
(68Hz)
ON
80Hz or higher
3 minutes
76Hz or
10 seconds
lower
-
OFF
Stop