Mitsubishi Electric PUHY-P250YHM-A Data Book page 36

(3) Wiring Method
1 Check the indoor unit setting (Refer to 7-5.(2) Wiring )
2 When using the external output function, connect each signal line to External output Terminal (TB22)
on the unit, depending on the usage.
3 When using external input function, peal the outer layer of the signal line off, and connect it to external
input terminal (TB21 or TB23) on the unit, depending on the usage.
Wiring On Site
Fix the wire on the low-
voltage (below DC30V)
clamp. Pull the wire
through the hole for
transmission line to
outside the unit. ✻2
Fix the wire on the high-
voltage (AC220-240V)
clamp. Pull the wire
through the hole for
transmission line to
outside the unit. ✻3
✻1 For instructions on how to install the short circuit plate on the 20HP indoor unit, refer to "Caution on using the
external input function" shown on the previous page.
✻2 Do not bundle with high-voltage (AC220-240V) wire, since noise interference from such wire may cause the
unit to malfunction.
✻3 Do not bundle with minute-voltage (DC30V or below) wire, since noise interference from such wire may cause
the unit to malfunction.
Caution
1) Wiring should be covered by insulation tube with supplementary insulation.
2) Use relays or switches with IEC or equivalent standard.
3) The electric strength between accessible parts and control circuit should have 2750V or more.
4) TB21 is a terminal specifically for No-voltage contact point input. Do not apply voltage to TB21, since it
must result in malfunction of indoor unit controller board.
5) TB23 is specifically for contact point input with voltage. Check the polarity before connecting to avoid
damage to the unit.
6) Keep the wires on the input side and on the output side away from each other when using AC220-
240V as a power source for displays.
7) Keep the length of the extension part of external signal line under 100m.
8) 20HP is shipped with B1 and B2 terminals of TB21 and A1 and A2 terminals of TB23 short-circuited
respectively. Do not eliminate this feature. If it is eliminated, the units in one of the two refrigerant circuits
may not operate.
To CN51 of No.1 board
To CN51 of No.2 board
32
Wiring inside the unit