Hitachi SJ300-037HFE 사용자 설명서

Configuring the Inverter for Multiple Motors

Oper

ations

a

nd Moni

tor

ing

For some applications, you may need to connect two 
or more motors (wired in parallel) to a single 
inverter’s output. For example, this is common in 
conveyor applications where two separate conveyors 
need to have approximately the same speed. The use 
of two motors may be less expensive than making the 
mechanical link for one motor to drive multiple 
conveyors.

Some of the requirements when using multiple 
motors with one drive are:

• Use only V/F (variable-frequency) control; do not use SLV (sensorless vector control).

• The inverter output must be rated to handle the sum of the currents from the motors.

• You must use separate thermal protection switches or devices to protect each motor. Locate 

the device for each motor inside the motor housing or as close to it as possible.

• The wiring for the motors must be permanently connected in parallel (do not remove one 

motor from the circuit during operation).

NOTE: The motor speeds are identical only in theory. That is because slight differences in 
their loads will cause one motor to slip a little more than another, even if the motors are identi-
cal. Therefore, do not use this technique for multi-axis machinery that must maintain a fixed 
position reference between its axes.

Some equipment manufacturers may have a single type of machine that has to support three 
different motor types—and only one motor will be connected at a time. For example, an OEM 
may sell basically the same machine to the US market and the European market. Some reasons 
why the OEM needs two motor profiles are:

• The inverter power input voltage is different for these markets.

• The required motor type is also different for each destination.

In other cases, the inverter needs two profiles because the machine characteristics vary accord-
ing to these situations:

• Sometimes the motor load is very light and can move fast. Other times the motor load is 

heavy and must move slower. Using two profiles allows the motor speed, acceleration and 
deceleration to be optimal for the load and avoid inverter trip (fault) events.

• Sometimes the slower version of the machine does not have special braking options, but a 

higher performance version does have braking features.

Having multiple motor profiles lets you store several “personalities” for motors in one 
inverter’s memory. The inverter allows the final selection between the three motor types to be 
made in the field through the use of intelligent input terminal functions [SET] and [SET3]. This 
provides an extra level of flexibility needed in particular situations. See the following page.

Inverter

to Nth motor

Motor 1

Motor 2

U/T1
V/T2

W/T3