Precautions For Use Of The Inverter - Mitsubishi Electric FR-A700 Technical Manual

1.6 Precautions for use of the inverter

The FR series is a highly reliable product, but incorrect peripheral circuit making or operation/handling method may shorten
the product life or damage the product.
Before starting operation, always recheck the following items.
1.6.1 Instructions on the inverter output side
Do not connect the power supply to the inverter output side terminal (U, V, W).
Application of power to the output terminals U, V, W of the
inverter will damage the inverter module. Especially when
there is a commercial power supply-inverter switchover
circuit, use mechanically interlocked magnetic circuit (MC1,
MC2) as shown on the right to prevent accidental
application of commercial power to the inverter output side.
To select the MC, refer to page 526 and use the ones
which have sufficient capacities from the magnetic switch
data. If the MC used have small capacities, this may be
connected with the commercial power supply by arcs at
current shut-off.
Also make connections so that the motor rotates in the
same direction (phase rotation) in both the commercial
power supply operation and inverter operation.
A short circuit or earth (ground) fault on the inverter output side may damage the
inverter modules.
Fully check the insulation resistance of the circuit prior to
inverter operation since repeated short circuits caused by
peripheral circuit inadequacy or an earth (ground) fault
caused by wiring inadequacy or reduced motor insulation
resistance may damage the inverter modules.
1) Fully check the to-earth (ground) insulation and phase
to phase insulation of the inverter output side before
power-ON.
Especially for an old motor or use in hostile
atmosphere, securely check the motor insulation
resistance etc.
Do not install a power factor correction capacitor, surge suppressor or capacitor type
filter on the inverter output side.
This will cause the inverter to trip or the capacitor and
surge suppressor to be damaged. If any of the above
devices are connected, immediately remove them.
common
(common)
MCCB
Power
supply
Bypass/inverter switch-over circuit
2) When - start is made during commercial powers
supply operation or a pole-change motor is used,
make up a circuit which provides mechanical
interlock and sufficient timing so that the circuit is not
shorted on the inverter output side (including arc
short).
114
SPECIFICATIONS
MC1
OCR
To be mechanically
interlocked
Inverter
MC
R/L1
U
S/L2
V
T/L3
W
MC2
Make connections after confirming that
phase rotation of commercial power
supply is in R→S→T sequence.
Motor
IM