Operating conditions
Cycle rate limit
Danfoss recommends a restart delay timer to
limit compressor cycling. The timer prevents
reverse compressor rotation, which may occur
during brief power interruptions. The system
must be designed in a way that guarantees
a minimum compressor running time of 2
minutes so as to provide for sufficient motor
cooling after start-up along with proper oil
return. Note that the oil return may vary since it
depends upon system design. There must be no
more than 12 starts per hour, a number higher
than 12 reduces the service life of the motor-
compressor unit. A three-minute (180-sec) time
out is recommended.
T
T
TH
TH
KA
A1
A2
A3
A1
180 s
A2
KA
~
~
Please contact Danfoss Technical Support for any deviation from this guideline.
The Liquid Injection Valve (LIV) is a UKV stepper
valve. This valve is closed when the compressors
is idle. An additional solenoid valve has to be
installed in case of power shortage to prevent
liquid entry to compressor when compressor is
off. Only one solenoid valve per unit is required.
Injection pick-up has to be done at the bottom
side of the liquid line piping and downstream the
filter dryer.
A filter is required before liquid injection pipe in
order to avoid debris blocking liquid injection
pipe.
A minimum 4k subcooling is necessary to ensure
good liquid injection.
20
FRCC.PC.022.A4.02
Application Guidelines
