Mitsubishi Heavy Industries FDT71VNXVD Service Manual page 22

(g) Over-current protection current safe controls I, II
Detecting the outdoor unit inverter input (primary) current and the output (secondary) current, if the current values exceed
setting values, the compressor speed (frequency) is controlled to protect the inverter.
Retention
Reset
B
Current (A)
(Fig. C) The control value "A" and the reset value vary depending
on the compressor speed.
24
22
20
18
16
Reset valve B
14
12
40 50 60 70
Compressor speed (frequency) (rps)
(h) Power transistor temperature protection
1) Protective control
If the power transistor temperature (detected with TIP) exceeds the setting value, the compressor speed (frequency)
is controlled to suppress the rise of power transistor temperature.
Reset
81
Power transistor temp. (°C)
(i) Anomalous power transistor current
1) Prevents over-current on the inverter. If the current value in the power transistor exceeds the setting value, the
compressor stops.
2) If the current value in the power transistor exceeds the specified value and the compressor stops 4 times within 30
minutes, E42 is displayed on the remote controller and it enters the anomalous stop mode.
(j) Anomalous inverter PCB
If the power transistor detects any anomaly for 15 minutes, including the stop of compressor, E51 is displayed on the
remote controller and it enters the anomalous stop mode.
(k) Anti-frost control by the compressor frequency control
1) If the indoor unit heat exchanger temperature (detected with Th
start of compressor, the compressor speed (frequency) is controlled to initiate the anti-frost control of indoor unit
heat exchanger.
2) When there are 3 indoor unit heat exchanger temperatures (Th
Reduces compressor frequency
at each minute.
3) Regarding the anti-frost control by the operation stop, refer to the operation control function by the indoor unit
controller and the cooling, dehumidifying frost prevention of page 10.
Reduces frequency
at each minute.
A
Control valve A
80 90 100 110 120 130
Reduces compressor frequency
at each minute.
Retention
85
Reset
Retention
1.5 3.5
Indoor unit heat exchanger temp. (°C)
-
22
Cooling
Model
Control
value A
71 15.0
Primary
100 13.5 (23.0) 12.5 (22.0) 13.5 (23.0) 12.5 (22.0)
current
side
125,
11.0 (23.0) 10.0 (22.0) 11.0 (25.0) 10.0 (24.0)
140
71 13.0
Secandary
100 11.5 (Fig.C) 10.5 (Fig.C) 11.5 (Fig.C) 10.5 (Fig.C)
current
side
125,
11.5 (Fig.C) 10.5 (Fig.C) 11.5 (Fig.C) 10.5 (Fig.C)
140
Note (1) Value in ( ) are for the single phase models.
-R) exceeds the setting value at 4 minutes after the
I
-R), the lowest temperature is detected.
I
-
'10 • PAC-SM-137A
Heating
Reset Control Reset
value B value A value B
14.0 16.0 15.0
12.0 13.0 12.0