Inverter Application Precautions; Selection - YASKAWA Varispeed E7 Instruction Manual And Parameter Description

Inverter Application Precautions

Selection

Observe the following precautions in selecting an Inverter.
Installing Reactors
A large peak current will flow in the power input circuit when the Inverter is connected to a large-capacity
power transformer (600 kVA or higher) or when switching a compensating capacitor. Excessive peak current
can destroy the convertor section. To prevent this, install a DC or AC reactor (optional) to improve the power
supply power factor.
DC reactors are built into 200 V class Inverters of 22 to 110 kW and 400 V class Inverters of 22 to 300 kW.
If a thyristor convertor, such as a DC drive, is connected in the same power supply system, connect a DC or
AC reactor regardless of the power supply conditions shown in the following diagram.
Inverter Capacity
When connecting special motors or multiple motors in parallel to an Inverter, select the Inverter capacity so
that the rated output current of the Inverter is minimum 1.1 times the sum of all the motor rated currents.
Initial Torque
The startup and acceleration characteristics of the motor are restricted by the overload current ratings of the
Inverter that is driving the motor. The torque characteristic generally is different from those when starting a
motor at a normal commercial power supply. If a large initial torque is required, select an Inverter with a
somewhat larger capacity or increase the capacity of both, the motor and the inverter.
Options
Terminals
connect any other devices to these terminals.
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Power supply
capacity
(kVA)
, 1, 2, 3 are for connecting only the options specifically provided by Yaskawa. Never
DC or AC reactor
Required
DC or AC reactor
Not required
Inverter capacity (kVA)
Fig 10.1