Service Manual

Protection Control SiUS181631EA
62 Functions and Control
4.2 Low Pressure Protection Control
Outline Low pressure protection control is used to protect compressors against the temporary decrease of
low pressure.
Cooling Operation
Heating Operation
Pe < 0.25 MPa (84 ftAq)
36 Hz Unload
Pe > 0.39 MPa (130 ftAq)
Pe
< 0.07 MPa (23 ftAq)
Low pressure not limited
Hot gas bypass valve = OFF
Hot gas bypass valve = ON
(R19081)
Low pressure
limited
Pe: Low pressure sensor detection value
Low pressure
standby
When occurring 3 times within 30 minutes,
the error code E4 is output.
Pe < 0.15 MPa
(50 ftAq)
Pe > 0.30 MPa
(100 ftAq)
&
Pe
> 0.09 MPa (30 ftAq)
or
Ts1 – Te
< 8˚C (14.4˚F)
Pe
> 0.06 MPa (20 ftAq)
After 10 sec.Pe
< 0.17 MPa (57 ftAq)
Pe
< 0.17 MPa (57 ftAq)
Pe
> 0.20 MPa (67 ftAq)
Pe < 0.07 MPa (23 ftAq)
After 15 sec.
Low pressure not limited
Low pressure limited
Current step limited
Hot gas bypass valve = OFF
Hot gas bypass valve = ON
(R19082)
Low pressure
standby
When occurring 3 times within 30 minutes,
the error code E4
is output.
Pe: Low pressure sensor detection value
Pe < 0.12 MPa
(40 ftAq)
Pe > 0.17 MPa
(57 ftAq)
Upper limit frequency: 3-step down
Upper limit frequency: 1-step up