MITSUBISHI ELECTRIC FR-S520 - Manual (Page 180)

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5
.1 Selecting Instructions
(1) Inverter capacity selection
When a special motor is run or multiple motors are run in parallel by one inverter,
choose the inverter capacity so that the sum of the rated motor currents (at 50Hz)
will be not more than the rated output current of the inverter.
(2) Motor starting torque
The starting and acceleration characteristics of an inverter-driven motor are
restricted by the overload capacity of the inverter used. The torque characteristic
is generally smaller than at a start made by the commercial power supply. When
large starting torque is necessary, choose automatic torque boost control (set the
motor capacity in Pr. 98) or adjust the torque boost value. If these selection and
adjustment cannot develop enough torque, choose a one rank higher inverter
capacity or increase both the motor and inverter capacities.
(3) Acceleration/deceleration time
The acceleration/deceleration time of the motor is determined by the motor-
generated torque, load torque and load's inertia moment (J).
If the current limit or stall prevention function is activated during
acceleration/deceleration, the time may increase, so change the
acceleration/deceleration time setting to a little longer value.
When you want to shorten the acceleration/deceleration time, increase the
torque boost value (if you set a too large value, the stall prevention function will
be activated at a start, resulting in increased acceleration/deceleration time),
use automatic torque boost control, or increase the inverter and motor
capacities.
5
.2 Peripheral Selecting Instructions
(1) Installation and selection of no-fuse breaker
To protect the inverter's primary side wiring, install a no-fuse breaker (NFB) on the
power receiving side. For selection of the NFB, refer to page 13 as it depends on
the power supply side power factor (which changes with the power supply voltage,
output frequency and load) of the inverter. Especially, a little larger capacity must
be chosen for a completely electromagnetic type NFB because its operation
characteristic changes with harmonic currents. Also, use the earth leakage circuit
breaker of our harmonic/surge suppression product. (Refer to page 15)