Frequency Control - Mitsubishi Electric PUHY-P200 Service Handbook

[5-2 Outdoor Unit Control ]
Operation
When Continuous heating
mode
5-2-6

Frequency Control

Depending on the capacity required, the frequency of the compressor is controlled to keep constant evaporation temperature
(0°C [32°F] = 0.71 MPa [103 psi]) during cooling operation, and condensing temperature (49°C [120°F] = 2.88 MPa [418 psi])
during heating operation.
The table below summarizes the operating frequency ranges of the inverter compressor during normal operation.
The OS in the multiple-outdoor-unit system operates at the actual compressor frequency value that is calculated by the OS
based on the preliminary compressor frequency value that the OC determines.
Model
200 model
250 model
300 model
350 model
400 model
450 model
500 model
The maximum frequency during heating operation is affected by the outdoor air temperature to a certain extent.
(1) Pressure limit
The upper limit of high pressure (63HS1) is preset, and when it exceeds the upper limit, the frequency is decreased every 15
seconds.
The actuation pressure is when the high-pressure reading on 63HS1 is 3.58MPa[519psi].
(2) Discharge temperature limit
Discharge temperature (TH4) of the compressor in operation is monitored, and when it exceeds the upper limit, the frequency
is decreased every minute.
Operating temperature is 115°C [239°F].
(3) Periodic frequency control
Frequency control other than the ones performed at start-up, upon status change, and for protection is called periodic frequen-
cy control (convergent control) and is performed in the following manner.
Periodic control cycle
Periodic control is performed after the following time has passed
30 seconds after either compressor start-up or the completion of defrost operation
30 seconds after frequency control based on discharge temperature or pressure limit
The amount of frequency change
The amount of frequency change is controlled to approximate the target value based on the evaporation temperature (Te) and
condensing temperature (Tc).
HWE14040
ON
P200-P400: Top part of heat exchanger is
being defrosted.
P450-P500: Right part of heat exchanger
is being defrosted.
Frequency/cooling (Hz)
Max Min
52 10
65 10
74 16
91 16
97 16
111 16
123 16
- 95 -
SV11
OFF
Other than on the left
Frequency/heating (Hz)
Max
56
71
88
105
110
122
129
Min
10
10
16
16
16
16
16
GB