Electronic soft starter
SIEMENS Low-Voltage Power Distribution

The soft-starting device is an electronic control for the soft startup of single-phase asynchronous machines. A phase control causes the current to rise steadily. This also increases the motor torque and the drive starts up smoothly. Because drive elements are handled more gently they can be designed more costefficient. As well as a considerable reduction in startup noise, this also helps prevent the tipping or sliding of materials to be transported. The starting current is minimized. There is no speed adjustment. There is no marked soft start behavior without a mechanically connected load.

If the power semiconductor is to be protected against short circuits or ground faults during startup, a super-quick fuse must be installed. Otherwise, the usual line and motor protective measures must be used. In the case of high switching frequencies, we recommend installing a thermistor motor protection for monitoring the permissible motor temperature.

The soft-starting device must not be operated with capacitive load. In order to ensure the safety of persons and systems, only qualified personnel should work on these devices.

To prevent losses in the device, the power electronics are bridged with relay contacts after startup. Can be retrofitted in existing plants at any time.

Benefits
- On completion of startup, the power semiconductors are bridged, which prevents overheating in the case of frequent starting and inhibits premature wear and tear.
- Separate setting of ramp up time and starting torque enables optimum adaptation to the mechanics.
- The LEDs for startup and continuous operation provide constant information on the operating state.