Wiring Precautions; When Using Separate Power Supplies For The Control Circuit And The Main Circuit - Mitsubishi Electric FR-A820-00046 (0.4K) Instruction Manual

2.6.4

Wiring precautions

• It is recommended to use a cable of 0.3 to 0.75 mm
• The wiring length should be 30 m (200 m for terminal FM) at the maximum.
• Use two or more parallel micro-signal contacts or twin contacts to prevent contact faults when using contact inputs since
the control circuit input signals are micro-currents.
Micro signal contacts
• 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 200 V 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 (A1, B1, C1, A2, B2, and C2) via a relay coil, lamp, etc.
• For the FR-A820-03160(55K) or higher and FR-A840-02160(75K) or higher, separate the wiring of the control circuit away
from the wiring of the main circuit.
Make cuts in rubber bush of the inverter side and lead the wires through.
Rubber bush
(viewed from inside)
2.6.5 When using separate power supplies for the
control circuit and the main circuit
 Cable size for the control circuit power supply (terminals R1/L11 and S1/
L21)
• Terminal screw size: M4
• Cable gauge: 0.75mm
• Tightening torque: 1.5 N·m
76
2. INSTALLATION AND WIRING
2.6 Control circuit
Twin contacts
Make cuts along the lines on
the inside with a cutter knife
2 2
to 2 mm
2
for the connection to the control circuit terminals.
<Wiring example>