Mitsubishi FR-A800

(H) Protective function parameter
PARAMETERS
333
5
GROUP
H
Electronic thermal O/L relay when using IPM motor (Pr.9, E.THM)
• This function detects the overload (overheat) of the motor and trips the inverter by stopping the operation of the transistor at
the inverter output side. (The operation characteristic is shown below.)
• Set the rated current (A) of the motor in Pr.9. Performing IPM parameter initialization automatically sets the rated current of
the IPM motor. (Refer to page 174.)
• Set "0" in Pr.9 to avoid activating the electronic thermal O/L 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))
NOTE
• 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.
• When using a PM motor other than MM-CF, set the free thermal parameters (Pr.600 to Pr.604) in accordance with the motor
characteristic.
• The transistor protection thermal O/L relay is activated early when the Pr.72 PWM frequency selection setting is increased.
•MM-CF
 The % value denotes the percentage to the rated motor current.
• Protective function activated area: the area right of the characteristic curve
• Normal operation area: the area left of the characteristic curve
80 100 120 140 160 200 220 240 260 280 300
Current [%]

(min) unit display in
this region(s) unit display in this region
Thermal relay
operation time [min]
50
60
70
0
60
120
180
240
Thermal relay operation time [s]
2000r/min
(133.33Hz) or lower
3000r/min
(200Hz)
2000r/min
(133.33Hz) or lower
3000r/min
(200Hz)
Range for the
transistor
protection