EDT 17-3 Smooth starting three-phase machines

Smooth starters use phase-angle control to reduce the motor voltage during switch-on. The starting current drops proportionally to the terminal voltage. The power component of a smooth starter is usually comprised of two thyristors per phase switched antiparallel. To keep the power losses and the contingent heat arising from this as low as possible, the power semiconductors are shunted by an integrated power circuit-breaker subsequent to the start-up phase.

Training objectives:

• Putting the system into operation
• Setting the parameters of the run-up and run-down ramp functions and starting voltage
• Investigating current and voltage during start-up
• Start-up with different loads
• Comparison to star-delta start-up