8510197P03 © Danfoss Commercial Compressors April-2007
Instructions
For the SH/SY/SZ 240 - 300 - 380 compressors, a
phase sequence controller function is built into
the external motor protection module (Refer to
Fig. 9).
• Compressor models SH 090 - 120 - 161 have
no internal reverse rotation protection. If re-
verse rotation occurs it will be obvious as soon
as power is turned on. The compressor will not
build up any pressure, the sound level will be ab-
normally high and power consumption will be
minimal. In such case, shut down the compres-
sor immediately and connect the phases to their
proper terminals. Although reverse rotation is
not destructive for the SH 090 - 120 - 161 for a
short period of time, prolonged reverse rotation
over 12 hours will damage the compressor.
•
The power supply connection is made by
means of a T-block connector (screw type 4.8
mm - 3/16”) and the thermostat connection is
made by means of a spade connector (1/4”-AMP-
AWE). For screw type connections, note that the
maximum tightening torque is 3 Nm.
•
A 5-mm earth terminal screw is provided in
the compressor junction box for the grounding
connection. All electrical components must be
selected as per local standards and compressor
requirements.
8 - Filling the system
•
Before charging the refrigerant, verify that the
oil level is between 1/2 and 3/4 on the compres-
sor oil sight glass (when mounted) and/or ensu-
re that the oil charge of the original compressor
is sufficient as regards system dimension and
piping design:
• An additional quantity of oil might be neces-
sary for line lengths (back and forth) in excess of
20 m.
• In the event additional oil is required, use only
an approved lubricant (refer to the “Introduc-
tion” section of this manual).
• An oil sight glass compressor model is
recommended for split systems and remote
condenser installations. For all information
necessary on adding oil to the compressor, refer
to TI bulletin 1-025.
•
Make sure the refrigerant used to fill the sys-
tem is compatible with compressor design. Re-
fer to the “Introduction” section of this manual
for an approved list of refrigerants.
•
Compressor switched off: The liquid refrige-
rant is charged into the condenser and/or liquid
receiver in the liquid phase (compulsory for re-
frigerant blends). The charge must be as close to
the nominal system charge as possible in order
to avoid both low pressure operations and ex-
cessive superheating at start-up. Throughout
this operation, both compressor service valves
must remain closed.
•
Remember that vapor-charging is only appro-
priate for pure refrigerants, such as R22.
•
To the extent possible, maintain the refrigerant
charge below the refrigerant charge limit for the
compressor model. Above this limit, install a
system, such as a pump-down cycle or suction
line accumulator, to prevent against liquid flood
back into the compressor.
•
Be sure that the refrigerant charge is suitable
for both winter and summer operations.
9 - Verification before commissioning
Ensure that all service valves are in the open
position before start-up. A closed discharge or
suction service valve may cause serious damage
to the compressor and/or compromise safety
device operation, thereby resulting in potential
injury to personnel.
•
Check that all safety devices are operational
and properly set (safety pressure switch set
point, mechanical relief valve if necessary, etc.).
Make sure that these devices comply with both
generally - and locally - applicable regulations
and standards (e.g. EN378).
•
When using high-pressure switches or relief
valves, the setting must not exceed maximum
service pressure of any system component. Re-
fer to the Application Guidelines for relevant
compressor pressure safety limits.
•
A low-pressure switch is recommended to pre-
vent operation under vacuum. Use a minimum
setting of SM/SY/SZ: 1.5 bar (absolute), SH: 1.6
bar.
•
Verify that all electrical connections are pro-
perly fastened and in compliance with local sa-
fety regulations.
•
When a crankcase heater is required (refer to
the Application Guidelines), ensure that it has
been energized for a minimum of 12 hours be-
fore initial start-up and/or during prolonged
shutdown periods.
Exception: On SH compressors, for initial start
up, due to R410A specific behaviour it is not re-
commended to energize the crankcase heaters
in advance.
10 - Start up
Never start the compressor in the absence of
a refrigerant charge.
•
Do not bypass the LP or any other safety
switches during start-up. Check current draw
and voltage levels.
•
Monitor the oil sight glass (when mounted)
for 60 min. to ensure proper oil return to the
compressor.
•
Suction superheat setting: Optimal compres-
sor suction superheat would be around 10K,
with the maximum allowable superheat being
30K.
•
In all cases, the application limits of the com-
pressor must be respected; moreover, high
superheat values lead to high discharge tem-
peratures and decrease compressor capacity.
The maximum discharge temperature is 135°C:
operating at a higher temperature may result in
refrigerant decomposition.
•
Under steady-state operating conditions,
check refrigerant piping or capillary tubes for
abnormal vibrations (refrigeration line move-
ment in excess of 1.5 mm necessitates corrective
actions, pipe brackets, etc.).
•
After 2 to 4 hours of operations under esta-
blished conditions, check the oil level and add
oil if necessary (refer to TI bulletin 1-025). If oil
return continues to perform poorly, further in-
vestigation of the piping design is required.
•
Ensure that refrigerant flow through the liquid
line sight glass (when mounted) is adequate and
that operating temperatures correspond with
system specifications.
•
When needed, refrigerant may be added in the
liquid phase, carefully throttling the refrigerant
on the low-pressure side and as far as possible
from the compressor. The compressor must be
operating during this process.
Do not overcharge the system.
11 - Troubleshooting
•
Compressor failure to start:
Verify that the
compressor is hooked up to the power supply;
check the power lead connections. If these veri-
fications reveal no abnormality, control the mo-
tor windings with an ohmmeter.
Note: When the internal motor protector has
tripped out (SM/SZ 084 - 090 - 100 - 110 - 120 -
124 - 147 - 148 - 161 and SH 090 - 105 - 120 - 140 -
161), it may take up to several hours to reset and
restart the compressor.
•
Compressor failure to build up pressure:
Check to make sure that all bypass valves in the
system have not been open. Also check that all
solenoid valves are in their proper position. For
SY/SZ 240 - 300 - 380, SH 380 models, if the inter-
nal pressure relief valve is opened, the compres-
sor sump will be warm and the compressor will
trip out on the motor protector. If this happens,
it may take up to 2 or 3 hours to reset.
•
Abnormal running noise:
Ensure the absence
of any liquid flood-back to the compressor by
means of measuring the return gas superheat
and compressor sump temperature. The sump
should be at least 10K above the saturated suc-
tion temperature under steady-state operating
conditions.
•
The high-pressure switch trips out:
Check
condenser operations (condenser cleanliness,
fan operations, water flow and water pressure
valve, water filter, etc.). If above check out OK,
the problem may be due to either refrigerant
over charging or the presence of a non-conden-
sable (e.g. air) in the circuit.
•
The low-pressure switch trips out:
Check
evaporator operations (coil cleanliness, fan ope-
rations, water flow, water filter, etc.), liquid refri-
gerant flow and pressure drops (solenoid valve,
filter dryer, expansion valve, etc.), refrigerant
charge.
•
Low refrigerant charge:
The correct refri-
gerant charge is given by the liquid sight glass
indication, the condenser delta T in relation to
