8510223 P01-A © Danfoss Commercial Compressors March 2006
Instructions
deep vacuum test.
• The test should be long enough in duration to
ensure the absence of any slow leaks in the system.
• Use tools specifically designed for detecting leaks.
• The low side test pressure must not exceed 1.1 x Ps
pressure indicated on the compressor nameplate.
• For high side test pressure recommendations,
please refer to the Application Guidelines.
• Whenever the compressor is equipped with
suction and discharge shut-off valves, these
valves are to remain in the closed position while
performing the leak test (compressor leak test
already performed in the factory).
• Should a leak be discovered, proceed with repair
steps and repeat the leak detection.
• When a deep vacuum leak detection test is
selected, observe the following:
1) The level to reach is 500 µm Hg.
2) Wait 30 min.
3) If pressure increases rapidly, the system is
not airtight. Locate and repair leaks. Restart the
vacuum procedure, followed by steps 1, 2, etc.
4) If pressure increases slowly, the system
contains moisture inside. Break the vacuum with
nitrogen gas and restart the vacuum procedure,
followed by steps 1, 2, etc.
5) Connect the compressor to the system by
opening the valves.
6) Repeat the vacuum procedure, followed by
steps 1, 2, etc.
7) Break the vacuum with nitrogen gas.
8) Repeat the vacuum procedure, steps 1, 2; a
vacuum of 500 µm Hg (0.67 mbar) should be rea-
ched and maintained for 4 hours. This pressure is
to be measured in the refrigeration system, and
not at the vacuum pump gauge.
Do not use a megohmeter or apply power to the
compressor while it is under vacuum, as this may
cause motor winding damage (motor burn-out).
Do not use colored leak detection fluids.
6 - Vacuum procedure
Whenever possible (if shut-off valves are present),
the compressor must be isolated from the system.
It is essential to connect the vacuum pump to
both the LP & HP sides, in order to avoid dead-
ending system parts.
Recommended procedure:
1) Once leak detection has been completed,
2) Pull down the system under a vacuum of 500
µm Hg (0.67 mbar).
3) When the vacuum level of 500 µm Hg has
been reached, the system must be isolated from
the pump.
4) A vacuum of 500 µm Hg (0.67 mbar) has
to be reached and maintained for 4 hours. This
pressure is to be measured in the refrigeration
system, and not at the vacuum pump gauge.
If pressure increases, restart the leak-detection
procedure (refer to the “Leak detection” section
of this manual if necessary).
Vacuum pump:
A two-stage vacuum pump with gas ballast (1.5-
mbar standing vacuum) shall be used; its capacity
is to be consistent with system volume. Never use
the compressor as a vacuum pump.
It is recommended to use large-diameter
connection lines and to connect these lines to
the shut-off valves, rather than to the Schrader
connection. This recommendation allows
avoiding excessive pressure losses.
Moisture level:
At the time of commissioning, system moisture
content may be as high as 100 ppm. During
operation, the liquid line filter dryer must reduce
this level to < 20 ppm.
Additional notes:
• To improve moisture removal, the temperature
of the system should not be lower than 10°C. If the
evaporator coil is equipped with electrical defrost
heaters, these heaters should be energized.
• A proper vacuum procedure is even more
important with HFC and polyolester lubricant
than it has “traditionally” been with HCFC (R22) or
CFC and mineral oil.
• For further details, please refer to TI 2-026.
Do not use a megohmeter or apply power to the
compressor while it is under vacuum, as this may
cause motor winding damage (motor burn-out).
7 - Electrical connections
• Make sure the main power supply to the system
has been switched off and isolated, in accordance
with applicable regulations, before performing
any electrical connection.
• Please refer to Fig 7, 8 and 9 for typical wiring
connections and examine the specific wiring
diagram located in the frequency converter
package. For further details, refer to the
application guidelines.
• Follow very closely the installation instruction
for frequency converter:
- See principal for mounting (fig 6): base frame
of the frequency converter needs to very well
fixed to the support to ensure a very good conti-
nuity between the earth potential of every elec-
trical panel and boxes of the system.
- See principal for wiring (fig 7, 8 and 9): bases
are that all control wires have to be of a screee-
ned design, the cable for electrical motor supply
has to be of a shielded design too. Correct ear-
thing of the shield cover has to be done using
the method shown on fig 8 and 9, every time this
one has to be earthed on each end of the cables.
Distinct cable tray must be used for control and
motor supply.
• The frequency converter ensures direct motor
protection and the factory set parameters are de-
signed such as it is protecting the motor over all
current malfunctions. So an external over-load is
not necessary.
• Set the frequency converter parameters in
accordance with Danfoss recommendations for
the couple of CD 302 frequency converter and
VTZ variable speed compressor.
• Maneurop® compressors are able to operate in
both directions (rotation).
• Depending on motor size, the power supply
connection utilizes either a spade connector (1/4”-
AMP-AWE) or a T-block connector (screw type 10-32
UNF x 9.5). For screw-type connections, be aware
that the maximum tightening torque is 3 Nm.
• A 5-mm earth terminal screw is provided in the com-
pressor 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 ¼ and ¾ on the compressor oil
sight glass (when mounted) and/or ensure that the
oil charge of the original compressor is sufficient as
regards system dimension and piping design:
- An additional quantity of oil might be necessary
for line lengths (back and forth) in excess of 20 m.
- An additional quantity of oil might be neces-
sary to compensate the quantity trapped in the
oil separator and oil reservoir when used.
- In the event additional oil is required, use only
an approved lubricant (refer to the “Introduction”
section of this manual).
- Use the compressor oil sight glass or the sight
glass from the oil level controller when used to
check the proper oil level when commissioning after
stabilization of the complete refrigeration system.
For all information necessary on adding oil to the
compressor, refer to TI 2-025.
• Make sure the refrigerant used to fill the system
is compatible with compressor design. Refer to
the “Introduction” section of this manual for an
approved list of refrigerants
• Compressor switched off: The liquid refrigerant
is charged into the condenser and/or liquid
receiver in the liquid phase (compulsory for
refrigerant blends). The charge must be as close
to the nominal system charge as possible in
order to avoid both low pressure operations and
excessive superheating at start-up. Throughout
this operation, both compressor service valves
must remain closed.
• Remember that vapor-charging is only
appropriate for pure refrigerants.
• To the extent possible, maintain the refrigerant
charge below 2.5 kg per cylinder. 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. EN 378).
• When using high-pressure switches or relief
valves, the setting must not exceed maximum
service pressure of any system component.
Refer to the Application Guidelines for relevant
compressor pressure safety limits.
• A low-pressure switch is recommended to
prevent operation under vacuum. Use a minimum
setting of 1.1 bar (absolute).
• Verify that all electrical connections are properly
fastened and in compliance with local safety
regulations.
• When a crankcase heater is required (refer
to the Application Guidelines), ensure that it
has been energized for a minimum of 12 hours
before initial start-up and/or during prolonged
shutdown periods.
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 on the
