• When using the Mitsubishi Electric constant-torque motor, set Pr.71 Applied motor = "1, 13 to 16, 50, 53, 54". (This setting
enables the 100% constant-torque characteristic in the low-speed range.)
Pr. 9 = 50% setting
of inverter rating*
Inverter output power (%)
(% to the inverter rated current)
When setting Pr.9 to a value (current value) of 50% of the inverter rated current
The % value denotes the percentage to the rated inverter current. It is not the percentage to the rated motor current.
When you set the electronic thermal relay function dedicated to the Mitsubishi Electric constant-torque motor, this characteristic curve applies to
operation at 6 Hz or higher. (For selection of the operation characteristic , refer to
Transistor protection is activated depending on the temperature of the heatsink. The protection may be activated even with less than 150%
depending on the operating conditions.
• The internal accumulated heat value of the electronic thermal relay function is reset to the initial value by the inverter's power
reset and reset signal input. Avoid unnecessary reset and power-OFF.
• Install an external thermal relay (OCR) between the inverter and motors to operate several motors, a multi-pole motor or a
dedicated motor with one inverter. When setting an external thermal relay, note that the current indicated on the motor rating
plate is affected by the line-to-line leakage current. (Refer to
operation. Use a thermal protector or a motor with built-in thermistor.
• The protective characteristic of the electronic thermal O/L relay is degraded when there is a large difference in capacity
between the inverter and motor, and when the set value is small. In such case, use an external thermal relay.
• A dedicated motor cannot be protected by an electronic thermal O/L relay. Use an external thermal relay.
• Set Pr.9 = "0" for Vector-control-dedicated motors (SF-V5RU) because they are equipped with thermal protectors.
• The transistor protection thermal O/L relay is activated early when the Pr.72 PWM frequency selection setting is increased.
Electronic thermal O/L relay when using IPM motor (Pr.9)
• This function detects the overload (overheat) of the motor and shut off the inverter output by stopping the operation of the
transistor at the inverter output side.
• Set the rated current (A) of the motor in Pr.9 Electronic thermal O/L relay. Performing IPM parameter initialization
automatically sets the rated current of the IPM motor. (Refer to
• Set "0" in Pr.9 to avoid activating the electronic thermal relay function; for example, when using an external thermal relay
for the motor.
(Note that the output transistor protection of the inverter is activated. (E.THT))
• Operational characteristic of the electronic thermal O/L relay when MM-CF is used.
5.10 (H) Protective function parameter
Pr. 9 = 100% setting
of inverter rating*
30Hz or more*
Region on the right of
Region on the left of
electronic thermal relay
function for motor
protection is turned off
(When Pr. 9 setting is 0(A))
114.) The cooling effect of the motor drops during low-speed