Справочник Пользователя для Mitsubishi Electronics FR-A701

This inverter is certified as a motor overload protection device by UL.
When using the electronic thermal relay function as motor overload protection, set the rated motor current to Pr. 9
Electronic thermal O/L relay. 

Electronic thermal relay function operation characteristic

This function detects the overload (overheat) of the 

motor, stops the operation of the inverter's output 

transistor, and stops the output. 

(The operation characteristic is shown on the left)

When using the Mitsubishi constant-torque motor

1) Set "1" or any of "13" to "18", "50", "53", "54" in Pr. 71. 

(This provides a 100% continuous torque characteristic 
in the low-speed range.)

2) Set the rated current of the motor in Pr. 9.

*1

When a value 50% of the inverter rated output current (current 
value) is set in Pr. 9 

*2

The % value denotes the percentage to the inverter rated output 
current. It is not the percentage to the motor rated current.

*3

When you set the electronic thermal relay function dedicated to the 
Mitsubishi constant-torque motor, this characteristic curve applies 
to operation at 6Hz or higher.

⋅ Protective function by electronic thermal relay function is reset by inverter power reset and reset signal input. Avoid

unnecessary reset and power-off.

⋅ When multiple motors are operated by a single inverter, protection cannot be provided by the electronic thermal relay function.

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 thermal relay function will be deteriorated. In this case, use an external thermal relay.

⋅ A special motor cannot be protected by the electronic thermal relay function. Use the external thermal relay.

⋅ Electronic thermal relay does not function when 5% or less of inverter rated current is set to electronic thermal relay setting.

For transistor protection
Electronic thermal relay 
function

52.5%

105%

50

100

150

60

120

180

240

50

60

70

6Hz

20Hz

10Hz

6Hz

0.5Hz

30Hz or more*

3

20Hz
10Hz

0.5Hz

Pr. 9 = 50% setting of 
inverter rating*

1.2

Pr. 9 = 100% setting 
of inverter rating*

1.2

(s) unit display in this range

(min) unit display in 

this range

Operation time (min)

Operation time (s)

Characteristic when 
electronic thermal relay 
function for motor 
protection is turned OFF 
(When 

Pr. 9 setting is 0(A))

30Hz 
or more*

3

Inverter output power (%)       
(% to the rated input current)

Operation range 
Range on the right of 
characteristic curve 
Non-operation range 
Range on the left of 
characteristic curve