Connecting Thermistor - Mitsubishi Electric PAC-IF012B Technical Manual

4. Connecting thermistor

4.1 Connecting thermistor cable
Connect the thermistor for the interface controller.
When the thermistor cables are too long, cut it to the appropri-
ate length.
Do not bind it in the interface unit.
1. Target temp. thermistor (TH1)
Connect the thermistor for the target temp. to 1 and 2 on
the terminal block (TB61) on the interface controller.
2. Pipe temp. thermistor / Liquid (TH2)
Connect the thermistor for the pipe temp. to 3 and 4 on
the terminal block (TB61) on the interface controller.
3. Pipe temp. thermistor / 2-phase (TH5).
Connect the thermistor for the 2-phase temp. to 5 and 6
on the terminal block (TB61) on the interface controller.
Set the DIP switch 2-6 to OFF of the interface controller.
Caution:
Do not route the thermistor cables together with power cables.
The sensor part of the thermistor should be installed where user must not touch.
(It is separated by the supplementary insulation from where user may touch.)
4.2 Thermistor position
< Target temp. thermistor (TH1) > (Used only in *auto step mode (Only for Air to Air applications))
1. Put thermistor (TH1) where average intake temperature for heat exchanger can be detected.
2. It is better to put thermistor (TH1) where radiant heat from heat exchanger can be avoided.
To use this interface for manual step control, put a fi xed resistor of 4~10kΩ instead of thermistor. (TH1 on the terminal block
TB61)
* Auto step mode: In this mode, the capacity step of the outdoor unit is controlled automatically to let the target (intake)
temperature reach the set temperature. (Only for air to air application)
< Liquid pipe thermistor (TH2) >
1. Put thermistor (TH2) where liquid refrigerant pipe temperature can be detected.
2. It is better to protect the thermistor (TH2) with heat insulating materials not to be affected by the ambient temperature, etc.
3. In case that the refrigerant is distributed by distributor, put thermistor (TH2) before the distributor.
< 2 phase pipe (condensing/evaporating) thermistor (TH5) >
*Only for Air to Air application (Refer to page. 4)
*Only in AUTO STEP mode of the I/F (Refer to page. 4)
1. 2 phase pipe thermistor must be located where the 2 phase (condensing / evaporating) temperature of HEX can be meas-
ured.
2. Preferably, it should be insulated to avoid any infl uences by the ambient air temperature and so.
3. It must be located where it does NOT measure hot gas/subcool liquid temperature in heating mode.
4. If HEX is divided into several paths, 2 phase pipe thermistor should be put on the upper path. (Liquid refrigerant tends to
stay in the lower path when HEX works as a condenser, and the improper temperature may possibly be picked up.)
5. 2 phase thermistor should be located in the middle of the path. If it is impossible to put it in the middle, it should be put a bit
inlet side of condenser. Do NOT move it too much to the inlet side, however, as it may possibly pick up hot gas temperature.
(Never put it on the outlet side of condenser as it may pick up subcool liquid temperature.)
TB61
TH1
TH2
TH5
30
Photo. 4-1