Measures Against Noise - Mitsubishi Electric PUHY-200YMF-C Service Handbook

3) Checking and measures to be taken
(a) Measures against noise
Check the items below when noise can be confirmed on wave shape or the error code in the item 1) is generated.
Items to be checked
1 Wiring of transmission and power lines in
crossing.
2 Wiring of transmission line with that of other
system in bundle.
3 Use of shield wire for transmission line (for
both indoor unit control and centralized
control).
4 Repeating of shield at the repeating of
transmission line with indoor unit.
5 Are the unit and transmission lines grounded
as instructed in the INSTALLATION MANUAL?
6 Earthing of the shield of transmission line (for
indoor unit control) to outdoor unit.
7 Arrangement for the shield of transmission line
(for centralized control).
(b) When the wave height value of transmission wave shape is low, 6607 error is generated, or remote controller is
under the state of "HO."
Items to be checked
8 The farthest distance of transmission line is
exceeding 200m.
9 The types of transmission lines are different.
0 No transmission power (30V) is being supplied
to the idoor unit or the remote control.
A Faulty indoor unit/remote controller.
Measures to be taken
Isolate transmission line from power line (5cm or more).
Never put them in a same conduit.
Wire transmission line isolating from other transmission line.
Wiring in bundle may cause erroneous operation like crosstalk.
Use specified transmission wire.
Type : Shield line CVVS/CPEVS
Wire diameter : 1.25mm
The transmission line is wired with 2-jumper system. Wire the shield
with jumper system as same for transmission line.
When the jumper wiring is not applied to the shield, the effect against
noise will be reduced.
Connect to ground as shown in the INSTALLATION MANUAL.
One point earthing should be made at outdoor unit.
Without earthing, transmission signal may be changed as the noise on
the transmission line has no way to escape.
For the shield earth of the transmission line for centralized control, the
effect of noise can be minimized if it is from one of the outdoor units in
case of the group operation with different refrigerant systems, and from
the upper rank controller in case the upper rank controller is used.
However, the environment against noise such as the distance of trans-
mission line, the number of connecting sets, the type of connecting con-
troller, and the place of installation, is different for the wiring for central-
ized control. Therefore, the state of the work should be checked as fol-
lows.
a) No earthing
• Group operation with different refrigerant systems
One point earthing at outdoor unit
• Upper rank controller is used
Earthing at the upper rank controller
b) Error is generated even though one point earth is being con-
nected.
Earth shield at all outdoor units.
Connect to ground as shown in the user's manual.
Measures to be taken
Confirm that the farthest distance from outdoor unit to indoor unit/
remote controller is less than 200m.
Use the transmission wire specified.
Type of transmission line
Wire dia. of transmission line
Refer to "Transmission Power Supply (30V) Circuit Check Procedure."
Replace outdoor unit circuit board or remote controller.
–98–
2
or more
: Shield wire CVVS/CPEVS
: 1.25mm 2 or more