Mitsubishi Electronics A800 ユーザーズマニュアル

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Checklist before starting operation
74
The converter unit and the inverter 
are correctly connected.
• 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.
When using the electronic bypass 
operation, electrical and mechanical 
interlocks are provided between the 
electronic bypass contactors MC1 
and MC2.
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 nor with PM motors.)
When switching to the commercial power supply operation while a failure 
such as an output short circuit is occurring between the magnetic contactor 
MC2 and the motor, the damage may further spread.
When a failure occurs between the MC2 and motor, make sure to provide a 
protection circuit, such as using the OH signal input.
-
A countermeasure is provided for 
power restoration after a power 
failure.
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.
-
Wheng using the vector control, the 
encoder is properly installed.
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.)
A magnetic contactor (MC) is 
installed on the converter unit's 
input side.
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.
The magnetic contactor on the 
inverter's output side is properly 
handled.
Switch the magnetic contactor between the inverter and motor only when 
both the inverter and motor are at a stop.
When using a PM motor, a low-
voltage manual contactor is installed 
on the inverter's output side.
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.
An EMI countermeasure is provided 
for the frequency setting signals.
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).
-
Checkpoint
Countermeasure
Refer 
to page
Check 
by user
Inverter/
converter unit
MC2
MC1
U
V
W
R/L1
S/L2
T/L3
IM
Power 
supply
Undesirable current
Interlock