Mitsubishi Electric F800-E Series Instruction Manual page 56

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.
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.
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.
When using a PM motor, a low-
voltage manual contactor is installed
on the inverter's output side.
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 terminal P/+ of the converter unit and terminal P/+ of the
inverter, and terminal N/- of the converter unit and 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 terminals P/+ and N/- (across terminals
P and P/+ or across N and N/-).
• Always connect terminal RDA of the converter unit and terminal MRS (X10)
of the inverter, and terminal SE of the converter unit and terminal SD
(terminal PC for source logic) of the inverter.
Not connecting these terminals may damage the converter unit.
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 PM 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.
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 JEM1038-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.
A PM motor is a synchronous motor with high-performance magnets
embedded inside. High-voltage is generated at the motor terminals while the
motor is running even after the inverter power is turned OFF. In an application,
such as fan and blower, where the motor is driven by the load, a low-voltage
manual contactor must be connected at the inverter's output side, and wiring
and inspection must be performed while the contactor is open. Otherwise you
may get an electric shock.
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.
PRECAUTIONS FOR USE OF THE INVERTER
Checklist before starting operation
MC1
Interlock
U
IM
V
MC2
W
Undesirable current
Refer
Check
to
by user
page
31
25
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52
52
3
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55