Design Information To Be Checked - Mitsubishi Electric Freqrol-A100 Instruction Manual

1.3.3 Design
Information
to be Checked
Provide electrical and mechanical interlocks for MC1
and MC2 which are used for commercial power supply-
inverter switch-over.
The inverter will be damaged not only by miswiring but also
by a sneak current from the power supply due to arcs
generated at the time of switch-over or chattering caused
by a sequence error, when there is a commercial power
supply-inverter switch-over circuit shown below.
-
Interlock
Power supply
T
MC2
!
Sneak current
Inverter
Since input signals to the control circuitare at a low
level, use two parallel micro signal contacts or twin
contact for contact inputs to prevent a contact fault.
Micro signal contacts Twin contact
Do not apply a voltage to the contact input terminals
(e.g. STF) of the control circuit.
When a machine restart i s to be prevented at power
restoration after a power failure, provide a magnetic
contactor MC in the primary circuit of the inverter 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.
Voltage
When connecting the control circuit to a power supply
separately from the main circuit, make up a circuit so
that when the power supply terminals R1, S1 for the
control circuit are switched off, the main circuit power
supply terminals R, S, T are also switched off.
Refer to page 16 for connection.
Do not apply a voltage directly to the alarm output
signal terminals (A, B, C).
Apply a voltage via a relay coil, lamp, etc. to these termi-
nals.
Voltage