Danfoss VLT MCD 600 Operating Manual page 63

Operating Guide | VLT® Soft Starter MCD 600
MOTOR DAMAGE
If the brake torque setting is too high, the motor stops before the end of the brake time and the motor suffers unnecessary
heating, which could result in damage. A high brake torque setting can also result in peak currents up to motor DOL being
drawn while the motor is stopping.
Careful configuration is required to ensure safe operation of the soft starter and the motor.
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Ensure that protection fuses installed in the motor branch circuit are selected appropriately.
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RISK OF OVERHEATING
Brake operation causes the motor to heat faster than the rate calculated by the motor thermal model.
Install a motor thermistor or allow sufficient restart delay (set in parameter 5-16 Restart Delay).
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70
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1 Parameter 2-10 Stop Time
3 Coast to stop time
Illustration 32: Example of Brake Time
Parameter settings:
• Parameter 2-9 Stop Mode: Set to DC Brake.
• Parameter 2-10 Stop Time: This is the total braking time (1) and must be set sufficiently longer than the brake time (in parameter 2-16
DC Brake Time) to allow the prebraking stage to reduce motor speed to approximately 70%. If the stop time is too short, braking will
not be successful and the motor will coast to stop.
• Parameter 2-15 DC Brake Torque: Set as required to slow the load. If set too low, the motor will not stop completely and will coast to
stop after the end of the braking period.
• Parameter 2-16 DC Brake Time: Set this parameter to approximately 1 quarter of the programmed stop time. This sets the time for
the full brake stage (2).
Danfoss A/S © 2018.10
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2
Time
N O T I C E
N O T I C E
2 Parameter 2-16 Brake Time
Operation
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