Справочник Пользователя для Mitsubishi Electronics FR-A500

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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.

*0.4K and 0.75K are set to 85% of the rated inverter current.

• Set the rated current [A] of the motor.

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

• Setting of "0" makes the electronic overcurrent protection (motor protective function) invalid. (The inverter's

output transistor protective function is valid.)

• When Mitsubishi constant-torque motor is used, set "1" or any of "13" to "18" in Pr. 71. (100% continuous

torque characteristic in the low speed range is selected.) Then, set the rated motor current in Pr. 9.

Note: 1. In S-shaped acceleration/deceleration pattern A (refer to page 86), the set time is a period

required to reach the base frequency set in Pr. 3.

• Acceleration/deceleration time calculation expression when the set frequency is the base

frequency or higher

        t = 

 

× 

 ×

 f

2

 + 

 T

T: Acceleration/deceleration time setting(s)

 f: Set frequency (Hz)

• Guideline for acceleration/deceleration time at the base frequency of 60Hz (0Hz to set frequency)

5

5

12

27

102

15

15

35

82

305

2. If the Pr. 20 setting is changed, the settings of calibration functions Pr. 903 and Pr. 905 (frequency setting

signal gains) remain unchanged. To adjust the gains, adjust calibration functions Pr. 903 and Pr. 905.

3. When the setting of Pr. 7, Pr. 8, Pr. 44, Pr. 45, Pr. 110 or Pr. 111 is "0", the acceleration/deceleration time

is 0.04s. At this time, set 120Hz or less in Pr. 20.

4. If the shortest acceleration/deceleration time is set, the actual motor acceleration/deceleration time

cannot be made shorter than the shortest acceleration/deceleration time determined by the mechanical
system's J (moment of inertia) and motor torque.

5. Changing the Pr. 21 setting changes the setting values of acceleration/deceleration time (Pr. 7, Pr. 8, Pr.

16, Pr. 44, Pr. 45, Pr. 110, Pr. 111, Pr. 264, Pr. 265). (The Pr. 611 setting is not changed.)
<Example>
When Pr. 21 = "0", setting "5.0"s in Pr. 7 and "1" in Pr.  21 changes the Pr.  7 setting to "0.5"s

9

Rated output current*

0 to 500A

Note: 1. 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.

2. When a 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.

3. A special motor cannot be protected by the electronic overcurrent protection. Use an external

thermal relay.

4

9

T

(Pr.3)

2

5

9

Related parameters

Pr. 71 "applied motor"