Service manual

Protection Control SiUS28-902_a
29 Function
4. Protection Control
4.1 High Pressure Protection Control
This high pressure protection control is used to prevent the activation of protection devices due
to abnormal increase of high pressure and to protect compressors against the transient
increase of high pressure.
[In cooling operation]
[In heating operation]
Pc > 512 psiEvery 10 sec.
Pc
> 505 psi
Pc
> 526 psi
10 sec.
Pc
< 490 psi
Pc>547 psi
Keeping the current step
Every 60 sec.
490 psi≤Pc≤505 psi
Every
5 min.
or
&
High pressure not limited
High pressure limited
INV. upper limit frequency:
1-step up from current
compressor frequency
INV. upper limit frequency:
1-step up from current
compressor frequency
Pc: HP pressure sensor detection value
INV. upper limit frequency :
1-step down from current
compressor frequency
When occurring 3 times within 30
minutes, HPS is activated without high
pressure standby, thus outputting the
malfunction code "
E3 ".
High pressure
standby
• INV. upper limit frequency
• Pc ≤ 483 psi
• During oil return operation
• After oil return operation
• Stopping operation
• Heating operation
57Hz
Pc > 469 psi
Pc
> 527 psi
57Hz
Pc
< 441 psi
High pressure not limited
High pressure
limited
High-pressure drop
Pc: HP pressure sensor detection value
When HPS is activated, the
malfunction code "
E3 " is output.
High pressure
standby