WEG SSW-08 User Manual - page 40

5

Programming Information and Suggestions

SSW-08 | 35 

Current

Torque

T/Tn

Tn

I/In

Figure 5.2: Characteristic curves of torque and current in a current limitation start

The following items show characteristic curves with the starting torque behavior according to 

some types of loads and their suggested controls.

5.1.1 Voltage Ramp Starting

1)  Set the value of the initial voltage to a low value;

2)  When a load is applied to the motor, set the initial voltage to a value that makes the motor 

rotate smoothly from the instant it is started.

3)  Set the acceleration time with the necessary start time, initially with short times, 10 to 15 

seconds, and afterwards try to find the best starting condition for the used load.

Start

Disable

Voltage Ramp

Enable

t(s)

0

100 %Un

U(V)

Figure 5.3: Voltage ramp starting

NOTE!

With long starting times, or when the motor is without a load, vibration can occur 

during the start of the motor, therefore lower the starting time;

If faults occur during the start, check all the connections from the Soft-Starter to 

the supply network, motor connections, supply network voltage levels, fuses and 

circuit breakers.