Specifications

Protections Ver: 0002 E - 7
2. PROTECTIONS OF THE MOTOR
The mechanical power limit of a motor is determined, among other causes, by the maximum
temperature allowed in its windings and, in motors with permanent magnets, by the
conservation of its magnetic properties.
As with the protection of the drives, the protection of the motors is watched in three modes at
the same time:
- Watch that the current does not exceed the maximum peak value permitted. To prevent
this, the drive limits the current command which it will attend to (i
command
) and it watches
the real instantaneous current (i
real
). See section 2.1.
- In permanent duty cycles, the motor temperature is monitored—
- by thermal sensors located in the motor. See section 2.2.
- by estimating the rms current based on the integral of the I
2
t product. This offers
a temperature estimate. See section 2.3.
2.1 PEAK CURRENT LIMIT AT THE MOTOR.
The operator may adjust the value of its parameter CP20 -F00307- to limit the current
command. Thus, the drive will never attend to current commands exceeding MP4 -S00109-,
which is the maximum peak current allowed at the motor.
That maximum peak current MP4 -S00109- is the one shown in the table of section SM.2 of
the general manual. This data is not related to any duty cycle (S3 or S6). It only sets a
preventive current limit to avoid demagnetizing the motor.
CP20 < MP4
MP4 -S00109- is a parameter for synchronous motors only.
In asynchronous motors, the current command is not monitored.
2.2 TEMPERATURE SENSORS IN THE MOTOR.
The motors have an overtemperature sensor (gage) PTC.
It is a triple sensor which permits detecting overtemperatures in the windings of each phase.
This sensor is connected to the drive through the feedback cable of the motor itself. Error 108
will be issued when the limit temperature for the motor is reached (which in Class F is 150°C
(302°F)).
The asynchronous motor also has a thermal Klixon switch that opens when those 150°C are
reached. This switch must be included in the emergency chain of the electrical cabinet.