Mitsubishi Electric 800 Series Hardware Instruction Manual page 92

Checkpoint
A countermeasure is provided for
an overload operation.
The specifications and rating
match the system requirements.
Countermeasures are taken
against electrical corrosion on the
motor bearing.
*1 Recommended common mode choke: FT-3KM F series FINEMET® common mode choke cores manufactured by Hitachi Metals, Ltd.
FINEMET is a registered trademark of Hitachi Metals, Ltd.
Countermeasure
When performing frequent starts/stops by the inverter, rise/fall in the
temperature of the transistor element of the inverter will repeat due to a repeated
flow of large current, shortening the life from thermal fatigue. Since thermal
fatigue is related to the amount of current, the life can be increased by reducing
current at locked condition, starting current, etc. Reducing current may extend
the service life but may also cause torque shortage, which leads to a start failure.
Adding a margin to the current can eliminate such a condition. For an induction
motor, use an inverter and a converter unit of higher capacities (up to two ranks).
For a PM motor, use an inverter and a converter unit, and PM motor of higher
capacities.
Make sure that the specifications and rating match the system requirements.
When a motor is driven by the inverter, axial voltage is generated on the motor
shaft, which may cause electrical corrosion of the bearing in rare cases
depending on the wiring, load, operating conditions of the motor or specific
inverter settings (high carrier frequency and EMC filter ON). Contact your sales
representative to take appropriate countermeasures for the motor. The following
shows examples of countermeasures for the inverter.
• Decrease the carrier frequency.
• Turn OFF the EMC filter.
• Provide a common mode choke
effective regardless of the EMC filter ON/OFF connector setting.)
*1
on the output side of the inverter. (This is
3. PRECAUTIONS FOR USE OF THE INVERTER
3.6 Checklist before starting operation
Refer to Check by
page user
1
2
—
3
—
4
5
—
6
7
8
9
10
91