Danfoss PSH051-4, Инструкции по применению

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Application guidelines
24
FRCC.PC.021.A5.22
Operating conditions
Liquid injection
Discharge temperature
protection
The OCS functionalities use the evaporating
pressure and condensing pressure signals,
and may be directly impacted by pressure
transmitters accuracy.
To fully benefit from OCS functionalities
(reliability features, overall application envelope
with transient conditions) it is recommended to
use ratiometric pressure transmitters (0-5V) with: • accuracy lower than ±16.68 psi a on high
pressure side, range 0-725 psi a
• accuracy lower than ±4.35 psi a on low
pressure side, range 0-508 psi a.
High pressure and low pressure transmitter
( connector) accessories are available
(refer to accessories list for code numbers).
PSH compressors require liquid injection
to maintain sufficiently low discharge gas
temperature within the entire operating
envelope. Liquid refrigerant is directly injected
into the scroll set.
PSH compressors are provided with a liquid
injection connection. Liquid pick-up has to be
done at the bottom side of the liquid line piping
and
downstream the filter drier .
The Liquid Injection Valve regulates the liquid
mass flow rate according to the discharge
temperature.
Liquid injection is active only for evaporating
temperature below 32°F and discharge
temperature above 284°F.
A minimum 9°F subcooling is necessary to ensure
correct liquid injection.
The Liquid Injection Valve (LIV) is a ETS6 stepper
valve. This valve is closed when the compressors
is idle.
Liquid injection valve accessory is available (refer
to accessories list for code numbers).
An additional solenoid valve has to be installed in
case of power shortage to prevent from liquid to
come back to the compressor. Only one solenoid
valve per unit is required. This solenoid valve
must be a normally closed (NC) valve and a direct
operation valve.
If discharge gas temperature exceeds 302°F and
in case of liquid injection issue (not enough
sub-cooling for example), the OCS will display
a warning. The unit has 5 minutes to decrease
the temperature below 302°F otherwise control
circuit M1-M2 will be opened. If discharge gas temperature reaches 320°F, the
control circuit M1-M2 will open.
Discharge gas temperature sensor accessory
( cable) is available (refer to accessories
list for code numbers).
Pressure transmitter
accuracy and range
Evaporator
EXV
LIV
HP sensor
LP sensor
Sol V
Discharge T sensor
Control
Condenser
Evaporator
EXV
LIV
HP sensor
LP sensor
Sol V
Discharge T sensor
Control
Condenser
Filter drier
In(P)
Pc
Pi
Po
h (kJ/kg)
Conditions
ACTION before condition
running out
Delay
ACTION once condition
has running out
Cumulated
time
ACTION once the boundary
condition has running out
302°F ≥ discharge
temp. < 320°F
WARNING W27 : “max.
discharge temp., stop in 5min”
5min.
ALARM A28 : “max. discharge temp. ,
compressor stopped”
ACTION : stop the compressor
RESTART : back to normal range
(≤293°F) then automatic reset
and manual reset after 4 repeated
occurrences in 24h.
1500h
WARNING W29 : “1500h above
max. disch. temp., change oil”
Discharge temp.
≥ 320°F
ALARM A28 : “max. discharge
temp. , compressor stopped”
0s no action 0s NA