Test Run and Others
5
TD831077
V-11
2. Electrical Work
2-2. Noise countermeasures of control
wiring
7 Signal line wiring between micro computer
mounted devices
Countermeasures: Signal connecting wiring, remote
controller wiring, and group control wiring between the
indoor / outdoor units
Along with the introduction of micro computer in air
conditioners, misoperation due to noise or inter-device
interference is at times generated. To prevent this,
always use a shielded wire for making serial communi-
cation.
¶ Types of shielded wires
*1. Use a shield wire having a shield of braided type
and twist pitch of about 2-inch or lesser.
*2. Use a core wire of 0.75 mm
2
or more thickness
*3. Use a wire of designated core count.
Core count designation:
Inter-indoor / outdoor unit connecting wires
... 2-core
shielded wire
¶ Engineering method
1. Ground the shield on both sides (Fig. 2-1)
2. Install the unit 3 m away from any nearby high
frequency equipment.
* House the remote controller into an iron box, and
its wiring into a wiring pipe or iron conduit.
3. Do not bundle the signal lines together with the power
line or wire them with the same cable. (Fig. 2-2)
* If wired together, keep the distance between them
more than 30 cm.
Current (A)
Distance between signal lines & power line
10 A or less 30 cm or more
50 A or less 50 cm or more
100 A or less 100 cm or more
4. Do not wire the signal lines of different equipment
with multi-core cables. (Fig. 2-3)
5. When using a noise filter or noise cut transformer,
firmly connect the earth wire of filter, etc. with the
main unit of air conditioner. Of course, install an
earth for the air conditioner. (Fig. 2-4)
6. Wire the primary and secondary side lead wires of
noise filter and noise guard transformer away from
each other. (Fig. 2-5)
7. Scrape off the paint from the joint of earth terminal in
order to ensure that its connection resistance does
not become large.
Multi-core cable
1077_1143
Communications equipment
A
B
C
D
A
B
C
D
no good
Filter
1079_1143
Secondary Primary
Filter
Secondary Primary
good
no good
Fig. 2-3
Shielded wire
1076_1143
Inter-unit wiring
Power supply wiring
no good
Shielded wire
0160_M_I
good
Fig. 2-2
Fig. 2-1
Fig. 2-5
Fig. 2-4
Filter
Air conditioner
Short
Earth
EE
1078_1143
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