Mitsubishi Electric FR-A820-04750-GF Instruction Manual page 117

2.6
Electronic thermal O/L relay (Pr.9)
• This function detects the overload (overheat) of the motor and shuts 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.
• 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 the EM-A motor is used
70
60
50
240
180
120
60
0
80 100 120 140 160 200 220 240 260 280 300
Protective function activated area: the area right of the characteristic curve
Normal operation area: the area left of the characteristic curve
*1 The % value denotes the percentage to the rated motor current.
NOTE
• The internal accumulated heat value of the electronic thermal relay function is reset to the initial value by the
inverter's power reset or reset signal input. Avoid unnecessary reset and power-OFF.
• The transistor protection thermal O/L relay is activated early when the Pr.72 PWM frequency selection setting is
increased.
2.7
Brake sequence function
The brake sequence function is available when the EM-A motor is used.
For details on the brake sequence function, refer to "5.14.3 Brake sequence function" in the Instruction Manual
(Detailed).
2.8
Automatic restart after instantaneous power failure function
The automatic restart after instantaneous power failure function is available when the EM-A motor is used.
When the EM-A motor is used, the frequency search is available at 450 r/min or higher.
For details on the automatic restart after instantaneous power failure function, refer to "5.14.15 Automatic restart after
instantaneous power failure/flying start with a PM motor" in the Instruction Manual (Detailed).
Range for the
transistor
protection
Current [%]
*
1
10 BCN-C22005-1008