Electronic thermal relay function operation characteristic
Pr. 9 = 50% setting of inverter rating*1, 2
Inverter output current(%)
(% to the rated inverter current)
Protective function by electronic thermal relay function is reset by inverter power reset and reset signal input. Avoid
unnecessary reset and power-OFF.
When two or more motors are connected to the inverter, they cannot be protected 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 an external thermal relay.
Electronic thermal relay may not function when 5% or less of inverter rated current is set to electronic thermal relay
Pr. 9 = 100% setting of inverter rating*2
30Hz or more
Range on the right of characteristic curve
Range on the left of characteristic curve
Characteristic when electronic thermal
relay function for motor protection is turned off
(when Pr. 9 setting is 0(A))
This function detects the overload (overheat)
of the motor, stops the operation of the
inverter's output transistor, and stops the
(The operation characteristic is shown on the
When using the Mitsubishi constant-torque
1) Set "1" or any of "13" to "16", "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.
When a value 50% of the inverter rated output
current (current value) is set in Pr. 9
The % value denotes the percentage to the
inverter rated output current. It is not the
percentage to the motor rated current.
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.