Daikin RZQS100B7V3B [100/344] Expansion valve control at startup

Daikin RZQS100B7V3B [100/344] Expansion valve control at startup
SiBE27-702 Expansion Valve Regulating Functions
Functional Description 87
5. Expansion Valve Regulating Functions
5.1 Expansion Valve Control at Startup
Outline Before going to the general expansion valve control, the expansion valve opening will be limited
in order to avoid the risk of liquid back and allow quick build up of pressure difference.
Details During startup, the opening degree is determined by both the compressor frequency & the
suction superheat. During startup, it is not possible to use only the value of the suction
superheat because the operation is not stable yet. As a consequence also the SH value will not
be stable.
Graph
RZQ71B9, RZQS71·100B7V3B (1 phase), RZQ100~140B8W1B (3 phase)
RZQ100~140C7, RZQS125·140C7V1B (1 phase)
Expansion valve
opening during
pressure
equalization
On RZQ71, RZQS71·100 units (using double swing compressor) the expansion valve will be
fully opened (to 480 pulses) for pressure equalisation before compressor start-up. Just before
compressor start up, the expansion valve opening will be set to 65 pulses, same as for the
RZQ100~140 class.
Ending condition The starting control will be terminated when the low pressure value < 6 bar or when the
maximum starting time of 10 minutes has been reached in case the low pressure value stays >
6 bar.
Compressor
Motorized valve
Pressure equalizing
control before
compressor start
Pressure
equalizing
start
Pressure
equalizing
complete
Starting
control
complete
Starting control
RZQ71, RZQS71·100: 1
φ
: 73Hz
RZQ100~140: 3
φ
: 107Hz
480 pls
65 pls
15 s
112Hz
Pressure
equalizing
complete
Starting
control
complete
Pressure equalizing
control before
compressor start
Starting
control
Compressor
Electronic
expansion valve
Cooling or
Heating(<25˚ C)
65 pls
Heating(>25˚ C)
480 pls
Pressure
equalizing
start

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