Mitsubishi Electric FR-A820-00046 Instruction Manual page 165

Precautions for use of the inverter
Checkpoint
The circuit is not configured to use
the inverter's input-side magnetic
contactor to start/stop the inverter
frequently.
A mechanical brake is not connected
across terminals P/+ and PR.
The voltage applied to the inverter
I/O signal circuits is within the
specifications.
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 the vector control, the
encoder is properly installed.
A magnetic contactor (MC) is
installed on the inverter's input side.
The magnetic contactor on the
inverter's output side is properly
handled.
Tab. 3-15:
FR-A800
Countermeasure
Since repeated inrush currents at power ON will shorten the life
of the converter circuit, frequent starts and stops of the
magnetic contactor must be avoided. Turn ON/OFF the
inverter's start signals (STF, STR) to run/stop the inverter.
Across terminals P/+ and PR, connect only an external brake
resistor.
Application of a voltage higher than the permissible voltage to
the inverter I/O signal circuits 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.
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 (SF-V5RU, SF-THY) nor with
PM motors.)
Power
supply
When 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 inverter'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, PM
sensorless vector control do not require an encoder.)
On the inverter's input side, connect an MC for the following
purposes:
To disconnect the inverter 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 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 inverter 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.
Checklist before starting operation (2)
Checklist before starting operation
Undesirable current
Inverter
Refer
Check
to
by user
page
3-9
2-87
2-44
Interlock
5-488
M
3~
⎯
2-71
3-17
3-17
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