Discharge Pipe Control; Input Current Control - Friedrich MW09C1H Service Manual

6.7 Discharge Pipe Control

Outline
The discharge pipe temperature is used as the compressor's internal temperature. If the discharge pipe temperature rises above a
certain level, the operating frequency upper limit is set to keep this temperature from going up further.
Detail
Divide the Zone
Management within the Zones
Stop zone
Drooping zone
Keep zone
Return / Reset zone

6.8 Input Current Control

Outline
Detect an input current by the CT during the compressor is running, and set the frequency upper
limit from such input current.
In case of heat pump model, this control is the upper limit control function of the frequency which
takes priority of the lower limit of four way valve activating compensation.
Detail
The frequency control will be made within the following zones.
When a "stop current" continues for 2.5 seconds after rushing on the stop zone, the compressor operation stops.
If a "drooping current" is continues for 1.0 second after rushing on the drooping zone, the frequency will be 2 Hz drooping.
Repeating the above drooping continues until the current rushes on the drooping zone without change.
In the keep zone, the frequency limit will remain.
In the return / reset zone, the frequency limit will be cancelled.
Limitation of current drooping and stop value according to the outdoor air temperature
1. In case the operation mode is cooling
* The current droops when outdoor air temperature becomes higher than a certain level (model by model).
2. In case the operation mode is heating
* The current droops when outdoor air temperature becomes higher than a certain level (model by model).
6.9 Freeze-up Protection Control
Outline
Heat exchanger
thermistor
temperature
Z o n e
When the temperature reaches the stop zone, stop the compressor and
correct abnormality.
Start the timer, and the frequency will be drooping.
Keep the upper limit of frequency.
Cancel the upper limit of frequency.
2 Hz drooping
After 2.5 seconds
1.0second after
rushing in the
drooping zone
1
2
3
Reset zone
Stop zone
Drooping zone
Keep zone
Up zone
Reset zone
C o t n o r c l o n e t n s t
Compressor stops
Stop zone
Drooping zone
Keep zone
Function and Control
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