Protective Functions - Panasonic CS-KS12NB41 & CZ-18BT1U + CU-KS12NK1A Technical & Service Manual

8-2. Protective Functions

Freeze prevention
During COOL or DRY operation, freezing is detected and
operation is stopped when the temperature of the indoor heat
exchanger matches the conditions below.
1. Freeze-prevention operation is engaged when the
temperature of the indoor heat exchanger is below 43°F(6°C).
2. Restart after freeze-prevention operation occurs when the
temperature of the indoor heat exchanger reaches 46°F(8°C)
or above.
46
(8)
A
43
(6)
36
(2)
*
a
Area: Automatic capacity control
a.
When the temperature drops below Point A, the operation
b.
frequency is reduced by a certain proportion.
Area: Frequency increase is prohibited.
c.
When the temperature reaches Point C or above, freezing
d.
prevention is ended and control is the same as in the
*
When the temperature drops to below 36°F(2°C)
(continuously for 2 minutes or longer), the compressor stops.
Once the freeze condition is detected, the air conditioner will
work less than the maximum frequency until it is turned off.
(CLxx models only)
NOTE
The Freeze Prevention Control during the Low Ambient Cooling
Mode (outside air temperature:59°F(15°C) or lower) is as follows.
The compressor stops when the temperature of indoor heat
exchanger becomes less than 36°F(2°C).
The compressor restarts when the temperature of indoor heat
exchanger becomes 46°F(8°C) or higher.
C
B
b c d
area.
a
Compressor discharge temperature control
This function controls the operation frequency to prevent the
compressor discharge temperature from rising more than a
specified temperature.
Compressor discharge temperature °F(°C)
Approx.
214
(101)
Approx.
201
(94)
a
Area: Automatic capacity control.
a.
When the temperature rises above Point A, the operation
b.
frequency is reduced at a specified rate.
Area: Further frequency increase is prohibited.
c.
When the temperature falls below Point B, prevention of a rise
d.
in frequency is released and the air conditioner operates as in
area.
a
*
The compressor will stop if the temperature of the compressor
discharge exceeds 248°F(120°C) due to shortage of gas or
other reason.
CT (Peak current cut-off control)
This function prevents the circuit breaker or fuse from operating
to open the circuit. This function works when electrical current
has increased due to an increase in the cooling load,
or to a decrease in the power supply voltage. In these cases,
operation frequency is reduced or operation is interrupted auto-
matically to control the electrical current for operation.
When the cause of the increase in electrical current is rectified,
the system will resume operation in the original mode.
<CS-KS12NB41>
Peak current cut-off trips
Hz down
<CS-KS18NB4UW>
Peak current cut-off trips
Hz down
50
A
B
b c d
Cooling Dry
22.5
14.0
Cooling Dry
17.5
11.0
(A)
(A)