Mitsubishi Electric FR-E700EX Manual page 45

Precautions for Peripheral Device Selection
Installation and selection of
moulded case circuit breaker
Install a moulded case circuit breaker (MCCB) on the power receiving
side to protect the wiring of the drive unit input side. For MCCB
selection, refer to page 43 since it depends on the drive unit power
supply side power factor (which changes depending on the power
supply voltage, output frequency and load). Especially for a completely
electromagnetic MCCB, one of a slightly large capacity must be
selected since its operation characteristic varies with harmonic
currents. (Check it in the data of the corresponding breaker.) As an
earth leakage current breaker, use the Mitsubishi earth leakage current
breaker designed for harmonics and surge suppression. (Refer to page
44)
When installing a moulded case circuit breaker on the output side of
the drive unit, contact each manufacturer for selection of the moulded
case circuit breaker.
Handling of the drive unit input
side magnetic contactor
 For operation via external terminal (terminal STF or STR used),
provide an input side MC to prevent an accident caused by a natural
restart at power recovery after a power failure, such as an
instantaneous power failure, and to ensure safety for maintenance
work. Do not use this magnetic contactor to make frequent starts
and stops. (The switching life of the drive unit input circuit is about
1,000,000 times.) For parameter unit operation, an automatic restart
after power failure is not made and the MC cannot be used to make
a start. Note that the primary side MC may be used to make a stop
but the regenerative brake specific to the drive unit does not operate
and the motor is coasted to a stop.
 Installation of a magnetic contactor at the input side is
recommended. A magnetic contactor avoids overheat or burnout of
a brake resistor when heat capacity of the resistor is insufficient or a
brake regenerative transistor is damaged with short while
connecting an optional brake resistor. In this case, shut-off the
magnetic contactor when fault occurs and drive unit trips.
Handling of the drive unit output
side magnetic contactor
Do not install a magnetic contactor at the drive unit's output side.
Thermal relay installation
When installing a thermal O/L relay (OCR) between the drive unit and
motor to protect the motor from overheating, set the electronic thermal
O/L relay of the drive unit to 0A. Note that the current indicated on the
motor rating plate is affected by the line-to-line leakage current (Refer to
page 48) when selecting the setting for a thermal relay.
Measuring instrument on the
output side
When the drive unit-to-motor wiring length is large, the meters and CTs
may generate heat due to line-to-line leakage current. Therefore,
choose the equipment which has enough allowance for the current
rating.
Disuse of power factor improving
capacitor (power capacitor)
The power factor improving capacitor and surge suppressor on the
drive unit output side may be overheated or damaged by the harmonic
components of the drive unit output. Also, since an excessive current
flows in the drive unit to activate overcurrent protection, do not install a
capacitor or surge suppressor. For power factor improvement, use a
DC reactor (Refer to page 37).
47
Wire thickness and wiring distance
When the wiring length between the drive unit and motor is long,
use thick wires so that the voltage drop of the main circuit cable is 2%
or less especially at low speed output. (A selection example for the
wiring distance of 20m is shown on page 43)
For remote operation via analog signal, wire the control cable between
the operation box or operation signal and drive unit within 30m and
away from the power circuits (main circuit and relay sequence circuit)
to prevent induction from other devices.
When using the external potentiometer instead of the parameter unit to
set the speed, use a shielded or twisted cable, and do not earth
(ground) the shield, but connect it to terminal 5 as shown below
(3)
10(10E)
(2)
2
(1)
5
Speed setting
Twisted
potentiometer
cable
Earth (Ground)
Always earth (ground) the drive unit and motor. In addition, always use
the earth (ground) terminal of the drive unit to earth (ground) the drive
unit. (Do not use the case and chassis)
Noise
The effect of electromagnetic interference must be reduced by using a
noise filter or by other means. Otherwise nearby electronic equipment
may be affected. Consider countermeasures referring to the following
countermeasure examples.
 As measures against AM radio broadcasting noise, radio noise filter
FR-BIF produces an effect.
 As measures against sensor malfunction, line noise filter FR-BSF01,
FR-BLF produces an effect.
 As measures against induction noise from the power cable of the
drive unit, an effect is produced by putting a distance of 30cm (at
least 10cm) or more and using a twisted pair shielded cable as a
signal cable. Do not earth (ground) shield but connect it to signal
common cable.
Noise reduction examples
Install common mode
FR-BLF
filter
Enclosure
FR-BSF01
on drive unit input side.
Drive unit
FR-
Drive
power
BSF01
unit
supply
Install capacitor type FR-BIF filter
FR-
on drive unit input side.
BIF
Separate drive unit and power
line by more than 30cm (at
least 10cm) from sensor circuit.
Control
Power
power supply
for sensor
supply
Do not earth (ground)
enclosure directly.
Do not earth (ground) control cable.
Shielded cable
(3)
10(10E)
(2)
2
(1)
5
Speed setting
potentiometer
Install common mode
FR-BLF
filter
FR-BSF01
on drive unit output side.
FR-
Motor
M
BSF01
Use 4-core cable for motor
power cable and use one
cable as earth (ground) cable.
Use a twisted pair shielded cable
Sensor
Do not earth (ground) shield but
connect it to signal common cable.