Mitsubishi Electric FR-D720 K Series Instruction Manual page 37

Control circuit specifications
(4) Signal inputs by contactless switches
The contacted input terminals of the inverter (STF, STR,
RH, RM, RL) can be controlled using a transistor
instead of a contacted switch as shown on the right.
(5) Wiring instructions
 It is recommended to use the cables of 0.3mm
 The maximum wiring length should be 30m (200m for terminal FM).
 Do not short across terminals PC and SD. Inverter may be damaged.
 When using contact inputs, use two or more parallel micro-signal contacts or
twin contacts to prevent contact faults since the control circuit input signals are
micro-currents.
 To suppress EMI, use shielded or twisted cables for the control circuit terminals and run them away from the main and
power circuits (including the 200V relay sequence circuit). For the cables connected to the control circuit terminals, connect
their shields to the common terminal of the connected control circuit terminal. When connecting an external power supply to
terminal PC, however, connect the shield of the power supply cable to the negative side of the external power supply. Do
not directly earth (ground) the shield to the enclosure, etc.
 Always apply a voltage to the fault output terminals (A, B, C) via a relay coil, lamp, etc.
26
External signal input using transistor
2 2
to 0.75mm gauge for connection to the control circuit terminals.
+24V
STF, etc.
Inverter
SD
Micro signal contacts Twin contacts