Mitsumi electronic 55K Electronic overcurrent protection Pr, Pr electronic thermal O/L relay

PARAMETERS

Note: 1. In S-shaped acceleration/deceleration pattern A (refer to page 79), 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 =	4		T		2		5
		×		× f		+		T
	9		(Pr.3)2				9

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)

Frequency setting (Hz)
Acceleration/	60	120
decelerationtime (s)
5	5	12
15	15	35

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 or Pr. 45 is "0", the acceleration/deceleration time is 0.04 seconds.

4.When the RT signal is on, the other second functions such as second torque boost are also selected.

5.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 (inertia moment) and motor torque.

4.2.6Electronic overcurrent protection (Pr. 9)

Pr. 9 "electronic thermal O/L relay"

Related parameter

Pr. 71 "applied motor"

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	Factory Setting	Setting Range	4
Number
9	Rated output current	0 to 500A

<Setting>

•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 using a Mitsubishi constant-torque motor, first set "1" in Pr. 71 to choose the 100% continuous torque characteristic in the low-speed range. Then, set the rated motor current in Pr. 9.

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.

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