Mitsubishi FR - S500 instruction manual Electronic overcurrent protection, DC injection brake

2.3.6 Electronic overcurrent protection

Set the current of the electronic overcurrent protection to protect the motor from overheat. This feature provides the optimum protective characteristics, including reduced motor cooling capability, at low speed.

Parameter	Name	Factory Setting	Setting Range
9	Electronic thermal O/L relay	Rated output current *	0 to 50A

* 0.1K to 0.75K are set to 85% of the rated inverter current.

<Setting>

Set the rated current [A] of the motor.

(Normally set the rated current at 50Hz if the motor has both 50Hz and 60Hz rated current.)

Setting "0" in Pr. 9 disables electronic thermal O/L relay (motor protective function). (The protective function of the inverter is activated.)

When using a Mitsubishi constant-torque motor, first set "1" in Pr. 71 "applied motor" to choose the 100% continuous torque characteristic in the low-speed range. Then, set the rated motor current in Pr. 9 "electronic thermal O/L relay".

CAUTION

•When two or more motors are connected to the inverter, they cannot be protected by the electronic overcurrent protection. Install an external thermal relay to each motor.

•When the difference between the inverter and motor capacities is large and the setting is small, the protective characteristics of the electronic overcurrent protection will be deteriorated. In this case, use an external thermal relay.

•A special motor cannot be protected by the electronic overcurrent protection. Use an external thermal relay.

♦ Related parameters♦

When constant-torque motor is used ⇒ Pr. 71 "applied motor" (refer to page 93)

2.3.7 DC injection brake

By setting the DC injection brake voltage (torque), operation time and operation starting frequency, the stopping accuracy of positioning

Output frequency (Hz)

Pr.10

"Operation

frequency"

operation, etc. or the timing of operating the

Pr.12

Time

DC injection brake to stop the motor can be adjusted according to the load.

DC injection brake voltage

"Operation

voltage"

Time

Pr.11 "Operation time"

64