100
400
200
10 20 30 40 50 60 70 80 90 100
1
Current (% motor full load current)
Time
Illustration 30: Example of Current Ramp Soft Starting
Parameter 2-3 Initial Current
Parameter 2-2 Start Ramp Time
Parameter 2-4 Current Limit
9.8.3 Constant Current with Kickstart
Kickstart provides a short boost of extra torque at the beginning of a start, and can be used with current ramp or constant current
starting.
Kickstart can be useful to help start loads that require high breakaway torque but then accelerate easily (for example helical rotor
pumps).
300
100
400
200
10 20 30 40 50 60 70 80 90 100
e77ha508.10
1
5
4
%
%
Current (% motor full load current)
Rotor speed (% full speed)
Illustration 31: Example of Kickstart used with Constant Current
Parameter 2-7 Kickstart Level
Parameter 2-6 Kickstart Time
Parameter 2-3 Initial Current
Parameter 2-2 Start Ramp Time
Parameter 2-4 Current Limit
9.8.4 Timed Voltage Ramp
Timed voltage ramp (TVR) soft starting ramps the application of voltage to the motor over a defined time period. The voltage ramp
reduces the initial starting torque and slows the motor's rate of acceleration.
TVR starting can be useful for applications where multiple motors of different sizes are connected in parallel, and/or the loads are
not mechanically linked.
AQ262141844215en-000401 / 175R117464 | Danfoss A/S © 2020.12
Operation
VLT® Soft Starter MCD 600
Operating Guide