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8-2. Current Control
The operating current may rise as a result of causes
including increasing heating or cooling loads or
decreases in power voltage. In these cases, the
operating frequency is automatically reduced, or
operation is stopped, in order to control the operating
current so that it is 20 A or less.
As a result:
• Power breakers and fuses will not be tripped.
• Operation can continue during this period with
somewhat reduced heating or cooling capacity.
• Operation at normal capacity is restored when the
cause of the current rise is eliminated.
Description of function
Example of operation for heating
22.5A
14.0A
13.6A
Target
frequency
Frequency
Stops operation
• Operates at the target frequency at Point A and below.
• Stops increases to the frequency between Points A and B.
• Reduces the frequency by 1 Hz per 0.5 seconds when Point B is exceeded.
• Stops operation, and restarts it approximately 3 minutes later, if Point C is
exceeded.
(May operate when sudden voltage fluctuations occur. → Indicates trouble.)
8-2-1. Automatic frequency control
The operating frequency is reduced automatically, or
operation is stopped, in order to control the operating
current so that it is at or below the values shown in the
table below.
Point C (peak cut trip)
Point B (Hz reduction)
Point A (Hz increase prohibit)
NOTE: During defrost operation, the COOL current
setting value is used.
8-2-2. Current control
The operating frequency upper limits shown in the figure
below are established for frequency reduction and
increase-prohibit.
Example of operation during cooling
Current (A)
Trip
Hz reduction
Hz increase
prohibit
8.5
8.1
0
30
Power Point C
Point B
Point A
Approx. 3 minutes
20A
HEAT
COOL
22.5
22.5
14.0
13.0
13.6
12.6
Hz reduction
Hz increase prohibit
Hz reduction
Hz increase prohibit
Frequency (Hz)
8-3. Low Start Current
Operation starts at 10 Hz, and the start current is less than
the normal operating current. This prevents the flickering of
fluorescent lights or television screens that occurs when
ordinary A/C units start.
8-4. Compressor Temperature Control
To protect the compressor coil from overheating, the
operating frequency is controlled based on the compressor
discharge temperature.
(°C)
124
108
100
No control
86
* Within the increase-prohibit range, the range changes
to the Hz reduction range (2 Hz every 30 seconds) if
the compressor temperature rises by 2°C.
8-5. Outdoor Fan Control
8-5-1. COOL operation
31°C
Maintain previous status
29°C
Less than 35 Hz
25
Trip
5Hz every 30 sec. reduction
2Hz every 30 sec. reduction
Increase
prohibit range
(Hz reduction)
Fan H
Fan H
Fan H
Fan L
Fan H
35 Hz
35 Hz or above
Frequency
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