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Design information
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 3) Low-level signal contacts
Power
supply
Inverter
Leakage current
Interloc
k
MC2
MC1
U
V
W
IM
R
S
T
Low-level signal contacts Twin contact