Control Specification SiUS12-928_B
59 Function and Control
3.5 Input Current Control
Outline An input current is detected by the CT while the compressor is running, and the frequency upper
limit is set from the input current.
In case of heat pump models, this control which is the upper limit control of the frequency takes
priority over the lower limit control of four way valve operation compensation.
Detail
Frequency control in each zone
Stop zone
After 2.5 seconds in this zone, the compressor is stopped.
Dropping zone
The upper limit of the compressor frequency is defined as operation frequency – 2 Hz.
After this, the output frequency is lowered by 2 Hz every second until it reaches the keep zone.
Keep zone
The present maximum frequency goes on.
Reset zone
Limit of the frequency is canceled.
Limitation of current dropping and stop value according to the outdoor temperature
The current drops when outdoor temperature becomes higher than a certain level (depending
on the model).
3.6 Freeze-up Protection Control
Outline During cooling operation, the signals sent from the indoor units control the operating frequency
limitation and prevent freezing of the indoor heat exchanger. (The signals from the indoor units are
divided into zones.)
Detail The operating frequency limitation is judged with the indoor heat exchanger temperature 2 seconds
after operation starts and 30 seconds after the number of operation room is changed.
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