Installation manual

[ VII Control ]
- 135 -
HWE10050 GB
(5) Bypass solenoid valve (SV5c) (ON = Open)
Compressor Frequency Control
-6- Compressor 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.
The maximum frequency during heating operation depends on the outside air temperature and the dipswitch settings.
(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).
Operation
SV5c
ON OFF
While the unit is stopped Always ON
Cooling mode When one or more of the following
valves is turned OFF: SV4a
through SV4c.
When the condition on the left is not
met
Defrost mode Always OFF on the P200 - P400 through EP200 - EP300 models and
always ON on the P450 and EP350 models.
Others Always OFF
Model
Frequency/cooling (Hz) Frequency/heating (Hz)
Max Min Max Min
P200 model 52 14 53 19
P250 model 65 14 71 19
P300 model 74 18 81 15
P350 model 95 18 101 15
P400 model 97 18 102 15
P450 model 111 18 117 15
EP200 model 52 14 53 19
EP250 model 58 18 67 15
EP300 model 74 18 81 15
EP350 model 95 18 101 15