Design Information - Mitsubishi Electric FR-S520E Series Instruction Manual

1.8 Design information

1) Provide electrical and mechanical interlocks for MC1 and MC2 which are used for
bypass operation.
When the wiring is incorrect and if there is a bypass operation circuit as shown
below, the inverter will be damaged by leakage current from the power supply due
to arcs generated at the time of switch-over or chattering caused by a sequence
error.
2) If the machine must not be restarted when power is restored after a power failure,
provide a magnetic contactor in the inverter's primary side and also make up a
sequence which will not switch on the start signal.
If the start signal (start switch) remains on after a power failure, the inverter will
automatically restart as soon as the power is restored.
3) Use two or more parallel micro-signal contacts or twin contacts to prevent a contact
fault when using contact inputs since the control circuit input signals are micro-
currents.
4) Do not apply a large voltage to the contact input terminals (e.g. STF) to the control
circuit.
5) Always apply a voltage to the alarm output terminals (A, B, C) via a relay coil, lamp
etc.
6) Make sure that the specifications and rating match the system requirements.
1) Bypass
Power
R
supply
S
T W
Inverter
MC1
Interlock
U
IM
V
MC2
Leakage current
3) Low-level signal contacts
Low-level signal contacts
51

Design information

Twin contact
1