6-14
[ 9 ]
dbh
Overheat protection for braking resistor
Problem Thermal protection for braking resistor activated.
Possible Causes What to Check and Suggested Measures
(1) Braking load was too
heavy.
Recalculate the relation between the braking load and braking
capacity.
Lighten the braking load.
Reconsider the choice of the braking resistor in order to
improve braking ability. Resetting the data of function codes
F50 and F51 is also required.
(2) The deceleration time was
too short.
Recalculate the required deceleration torque and time from the
moment of inertia for the load and the deceleration time.
Increase the deceleration time (F08, E11, and H54).
Reconsider the choice of the braking resistor in order to
improve the braking ability. Resetting the data of function
codes F50 and F51 is also required.
(3) Incorrect values have
been set for the data of
function codes F50 and
F51.
Check the braking resistor specifications.
Reconsider and change the data of function codes F50 and
F51.
Note: The inverter does not detect the overheating alarm of a braking resistor by monitoring its
surface temperature, but by monitoring its load magnitude.
Therefore, even if the surface temperature itself does not rise, the alarm may be detected if the
resistor is used more frequently than the set data of function codes F50 and F51. If you use the
resistor to the limit of its capacity, you must adjust the data of function codes F50 and F51 while
checking the surface temperature of the resistor.
[ 10 ]
0l1
Electronic thermal overload relay
Problem Electronic thermal function for motor overload detection was activated.
Possible Causes What to Check and Suggested Measures
(1) Load was too heavy. Measure the output current.
Lighten the load (e.g., lighten the load before overload
occurs using the overload early warning (E34)).
(2) The acceleration/
deceleration time was too
short.
Check that the motor generates enough torque fo
acceleration/deceleration. This torque is calculated from the
moment of inertia for the load and the acceleration
deceleration time.
Increase the acceleration/ deceleration time (F07, F08, E10,
E11 and H54).
(3) The characteristics of
electronic thermal did not
match those of the motor
overload.
Check the motor characteristics.
Reconsider the data of function codes P99, F10 and F12.
Use an external thermal relay.
(4) Activation level for the
electronic thermal relay
was inadequate.
Check the continuous allowable current of the motor.
Reconsider and change the data of function code F11.
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