Pump Down; Control Box And Connecting Position Of Wiring - Mitsubishi Electric PUMY-P125YMA Installation Manual

8.5. Pump down

Before removing air conditioners for transfer to another location, always close the
stop valve (for both liquid and gas pipes) located at the outdoor unit, then remove
the indoor and outdoor units. At this time, the refrigerant in the indoor unit will be
discharged. To minimize the refrigerant discharged, a pump down operation is
required. This operation collects the refrigerant present inside the air conditioner
and sends it into the heat exchanger located in the outdoor unit.
Pump down procedure
1 Operate all indoor units in cooling mode and check that the operation mode
has changed to "COOL". (Set the units so that cooling operation mode is acti-
vated during the pump down operation (when the TEST RUN button is pressed).)
2 Connect a gauge manifold valve (with pressure gauge) to the stop valve of the
gas pipe, to enable measurement of refrigerant pressure.
3 Check that the operation is stopped and switch the outdoor service switch
[SW5-3] (pump down switch) from OFF to ON.
4 Press the outdoor service switch [SW3-1,2] (test run switch) to start operation
in cooling mode.
5 After the cooling operation has been carried out for approximately five min-
utes, close the stop valve on the liquid pipe, with the cooling operation still ON.
(Pump down operation will start.)
6 When the reading of the pressure gauge reaches 0 to 0.1 MPa (0 to 1 kg/
cm 2 G) or when approximately 5 minutes have elapsed following the start of
the pump down operation, fully close the stop valve on the gas pipe and stop
the air conditioner by pressing the outdoor service switch [SW3-1,2] immedi-
ately.
9. Wiring
9.1. Caution
1 Follow ordinance of your governmental organization for technical standard re-
lated to electrical equipment, wiring regulations and guidance of each electric
power company.
2 Wiring for control (hereinafter referred to as transmission line) shall be (5 cm or
more) apart from power source wiring so that it is not influenced by electric
noise from power source wiring. (Do not insert transmission line and power
source wire in the same conduit.)
3 Be sure to provide designated grounding work to outdoor unit.
4 Give some allowance to wiring for electrical part box of indoor and outdoor
units, because the box is sometimes removed at the time of service work.
5 Never connect the main power source to terminal block of transmission line. If
connected, electrical parts will be burnt out.
6 Use 2-core shield cable for transmission line. If transmission lines of different
systems are wired with the same multiplecore cable, the resultant poor trans-
mitting and receiving will cause erroneous operations.
7 Only the transmission line specified should be connected to the terminal block
for outdoor unit transmission.
(Transmission line to be connected with indoor unit : Terminal block TB3 for
transmission line, Other : Terminal block TB7 for centralized control)
Erroneous connection does not allow the system to operate.
8 In case to connect with the upper class controller or to conduct group opera-
tion in different refrigerant systems, the control line for transmission is required
between the outdoor units each other.
Connect this control line between the terminal blocks for centralized control.
(2-wire line with no polarity)
When conducting group operation in different refrigerant systems without con-
necting to the upper class controller, replace the insertion of the short circuit
connector from CN41 of one outdoor unit to CN40.
9 Group is set by operating the remote controller.
9.2. Control box and connecting position of
wiring
1. Connect the indoor unit transmission line to transmission terminal block (TB3),
or connect the wiring between outdoor units or the wiring with the central con-
trol system to the central control terminal block (TB7).
12
7 Switch the outdoor service switch [SW5-3] from ON to OFF.
8 Remove the gauge manifold valve and put the cap back onto each stop valve.
Notes:
1 Never carry out pump down operation if the amount of refrigerant inside
the indoor unit is larger than the amount of charge-less refrigerant.
Carrying out a pump down operation when the amount of refrig-
erant exceeds the amount of charge-less refrigerant will cause
an extreme pressure rise and may result in an accident.
2 The service switch [SW5-3] can only be changed over while the com-
pressor is stopped. If you have changed over this service switch even if
the compressor is still in operation, stop the operation, then retry to
change it over.
Do not continue to operate for a long time with the switch [SW5-3] set to
ON.
Make sure to switch it to OFF after pump down is completed.
3 Test run can be carried out when the test run switch [SW3-1] is ON. Switch
[SW3-2] is used to start and stop operation.
4 Time required for a pump down operation is three to five minutes after
the stop valve on the liquid pipe has been closed. (It depends on the
ambient temperature and amount of refrigerant inside the indoor unit.)
5 Ensure that the reading of the pressure gauge does not drop below 0
MPa (0 kg/cm 2 G). If it drops 0 MPa (0 kg/cm
air will be drawn into the unit if there are any loose connections.
6 Even if the reading of the pressure gauge does not drop below 0 MPa (0
kg/cm 2 G), always stop the pump down operation within approximately
five minutes after the stop valve on the liquid pipe has been fully closed.
When using shielded wiring, connect shield ground of the indoor unit transmis-
sion line to the earth screw ( ) and connect shield ground of the line between
outdoor units and the central control system transmission line to the shield (S)
terminal of the central control terminal block (TB7) shield (S) terminal. In addi-
tion, in the case of outdoor units whose power supply connector CN41 has
been replaced by CN40, the shield terminal (S) of terminal block (TB7) of the
central control system should also be connected to the ground (
[Fig. 9.2.1] (P.5)
A Power source
2. Conduit mounting plates (ø27) are being provided. Pass the power supply and
transmission wires through the appropriate knock-out holes, then remove the
knock-out piece from the bottom of the terminal box and connect the wires.
3. Fix power source wiring to terminal box by using buffer bushing for tensile
force (PG connection or the like).
9.3. Wiring transmission cables
1 Types of control cables
1. Wiring transmission cables
• Types of transmission cables: Shielding wire CVVS or CPEVS
• Cable diameter: More than 1.25 mm
• Maximum wiring length: Within 200 m
2. Remote control cables
Kind of remote control cable 2-core cable (unshielded)
Cable diameter 0.3 to 1.25 mm
When 10 m is exceeded, use cable with the
Remarks
same specifications as (1) Transmission line
wiring
2 Wiring examples
• Controller name, symbol and allowable number of controllers.
Name Symbol
Outdoor unit controller OC
Indoor Unit Controller IC
RC
Remote Controller (M-NET)
MA
2 G) (i.e. vacuum is created),
).
B Transmission line
2
2
Allowable number of controllers
One to eight controllers for one OC
Maximum of 16 controllers for one
OC
Maximum of two per group