2)
Pressure limit
The upper limit of high pressure (Pd) is set for each frequency.
When the limit is exceeded, frequency is reduced every 10 seconds.
(Frequency decrease rate (Hz) : 22% of the present value)
<P200YMF-C>
3)
Discharge temperature limit
Discharge temperature (Td) of compressor is detected during operation. If the upper limit is exceeded, the fre-
quency is reduced. (Change rate : 5% of the present value)
• 30 seconds after starting compressor, control is performed every minute.
• Operation temperature is 130˚C.
4)
Periodical frequency control
Frequency controll is periodically performed except for the frequency controls at operation start, status change, and
protection.
1 Cycle of periodical frequency control
Periodical frequency control is performed every minute after the time specified below has passed.
• 20 sec after starting compressor
• 20 sec after frequency control by discharge temperature or pressure limit
2 Amount of frequency change
The amount of frequency change is controlled corresponding to evaporation temperature and high pressure
saturation temperature.
3 Back up of frequency control by bypass valve
During 20Hz operations, frequency is backed up by turning on (opening) bypass valve (SV2).
• Cooling
During 20Hz operations 3 minutes after starting compressor, bypass valve is turned on when,
Ps is 1.5kg/cm
2
• Heating
During 20Hz operations 3 minutes after starting compressor, SV2 turned on when high pressure (Pd) exceeds
pressure limit and turned off when Pd falls to 20kg/cm
(5) Oil return control (Electronic expansion valve <SLEV>)
• Oil return LEV (SLEV) opening is dependent on compressor frequency and ambient temperature.
• SLEV is closed (0) when compressor stops, and SLEV is set (50) for 10 minutes after starting compressor.
G (0.15MPa) or less and turned off when Ps is 2.5kg/cm
ON
OFF
2
1.5kg/cm
G
2.5kg/cm
(0.15MPa)
(0.25MPa)
2
G (1.96MPa) or less.
ON
OFF
2
2
G
20kg/cm
G
(1.96MPa)
–50–
<P250YMF-C>
2
G (0.25MPa) or more.
2
27kg/cm
G
(2.65MPa)