Soft starters deliver more torque with less vibration
15 April 2011
Soft starters in the new DS7 range from Eaton’s Electrical Sector combine smooth starting and freedom from vibration, previously only available from three-phase units, with the economy and space savings of a two-phase soft starter. In addition, as fully integrated elements of the Eaton xStart motor control range, they offer the convenience of fast, simple tool-free connection with motor protection relays and circuit breakers.
DS7 soft starters, which are available with ratings from 1.1kW to 15kW on 400V three-phase supplies, feature a patented asymmetric triggering system that eliminates DC components in the supply to the motor during starting. This ensures smooth starting, allows the units to deliver more starting torque and reduces motor heating. The low level of motor vibration during starting also minimises wear on mechanical components, extending their lives and reducing maintenance requirements.
The new soft starters simply clip together with PKZ and PKE motor protection devices to produce complete starter assemblies. No additional wiring is needed for the power circuits, which not only saves time but also eliminates the possibility of wiring errors. Accessory connectors are also available to provide plug-and-socket connections between motor and the DS7 soft starter. When these are used, conventional motor terminals are no longer needed in the control panel.
Soft starters in the DS7 range are just 42mm wide, the same as xStart motor protection devices, and therefore occupy very little space in the control panel. As supplied, they are rated for up to ten starts per hour, each with a starting current of three times full load for a maximum of five seconds. More arduous duties can, however, be accommodated by adding an optional cassette fan which simply slips into place within the starter without affecting its overall dimensions.
Eaton’s new DS7 soft starters can be supplied for use with 24V ac/dc or 110/230V ac control circuits. A SmartWire Darwin interface, to minimise control wiring, facilitate remote monitoring and allow easy interfacing with popular fieldbus systems, will be available in the near future.
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