Mitsubishi Electric FR-A802-P Instruction Manual page 82

Checkpoint
The voltage applied to the I/O signal
circuits of the inverter and the
converter unit is within the
specifications.
The converter unit and the inverter
are correctly connected.
The RS-485 terminals are correctly
connected.
When using the electronic bypass
operation, electrical and mechanical
interlocks are provided between the
electronic bypass contactors MC1
and MC2.
A countermeasure is provided for
power restoration after a power
failure.
When using vector control, the
encoder is properly installed.
A magnetic contactor (MC) is
installed on the converter unit's
input side.
The magnetic contactor on the
inverter's output side is properly
handled.
An EMI countermeasure is provided
for the frequency setting signals.
Countermeasure
Application of a voltage higher than the permissible voltage to the I/O signal
circuits of the inverter and the converter unit or opposite polarity may
damage the I/O devices. Especially check the wiring to prevent the speed
setting potentiometer from being connected incorrectly to short circuit the
terminals 10E and 5.
• Make sure that the terminal P/+ of the converter unit and the terminal P/+ of
the inverter, and the terminal N/- of the converter unit and the terminal N- of
the inverter are correctly connected.
Connecting the opposite polarity of terminals N/- and P/+ will damage the
inverter.
Also, do not install an MCCB across the terminals P/+ and N/- (across
terminals P and P/+ or across N and N/-).
• Always connect the terminal RDA of the converter unit and the terminal
MRS (X10) of the inverter, and the terminal SE of the converter unit and the
terminal SD (terminal PC for source logic) of the inverter.
Not connecting these terminals may damage the converter unit.
Always connect wiring to the RS-485 terminals of the master/slave inverters.
If the RS-485 communication is not performed correctly, the parallel
operation cannot be made.
When using a switching circuit as shown below, chattering due to mis-
configured sequence or arc generated at switching may allow undesirable
current to flow in and damage the inverter. Mis-wiring may also damage the
inverter.
(The commercial power supply operation is not available with vector control
dedicated motors.)
Power
R/L1
supply
S/L2
T/L3
Inverter/
converter unit
If switching to the commercial power supply operation while a failure such as
an output short circuit has occurred between the magnetic contactor MC2
and the motor, the damage may further spread. If a failure has occurred
between the MC2 and the motor, a protection circuit such as using the OH
signal input must be provided.
If the machine must not be restarted when power is restored after a power
failure, provide an MC in the converter unit's input 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.
The encoder must be directly connected to a motor shaft without any
backlash. (Real sensorless vector control does not require an encoder.)
On the converter unit's input side, connect an MC for the following purposes:
• To disconnect the inverter and the converter unit from the power supply at
activation of a protective function or at malfunctioning of the driving system
(emergency stop, etc.).
• To prevent any accident due to an automatic restart at power restoration
after an inverter stop made by a power failure.
• To separate the inverter and the converter unit from the power supply to
ensure safe maintenance and inspection work.
If using an MC for emergency stop during operation, select an MC regarding
the converter unit input side current as JEM 1038-AC-3 class rated current.
Switch the magnetic contactor between the inverter and motor only when
both the inverter and motor are at a stop.
If electromagnetic noise generated from the inverter and the converter unit
causes frequency setting signal to fluctuate and the motor rotation speed to
be unstable when changing the motor speed with analog signals, the
following countermeasures are effective:
• Do not run the signal cables and power cables (inverter and converter unit I/
O cables) in parallel with each other and do not bundle them.
• Run signal cables as far away as possible from power cables (inverter and
converter I/O cables).
• Use shielded cables.
• Install a ferrite core on the signal cable (Example: ZCAT3035-1330 TDK).
PRECAUTIONS FOR USE OF THE INVERTER
Checklist before starting operation
MC1
Interlock
U
IM
V
MC2
W
Undesirable current
Refer Check
to page by user
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