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Soft Starter Overview

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The NSFTxx soft starters are fully protected, digitally-controlled and programmable units. They are simple to install and are effectively employed in applications driving:

• Transport systems (conveyors, escalators, roller tables etc.) for low inertia loads,
• Pumps and compressors,
• Inelastic transmissions (gear trains, high-ratio belt systems etc.), and
• Fans and ventilators.

Main features of the line include:

• Generous x4 starting current and cooling circuit design provides for 60-555 A (starting, per phase), 10-90 HP/7.5-66 kW (at 3x400 V) loads. The employed 1600 VDC power circuit allows our soft starters to be used in up to 3x480 VAC systems.
• User selectable starting current limitation to control the acceleration torque.
• Complete and comprehensive electronic protection:

1. Overcurrent: load current is monitored in each phase and the overload limit is set by the user.
2. Undercurrent: to detect mechanical coupling problems (such as loose belts and uncoupled transmissions) and unloaded conditions (such as a dry pump).
3. Over/Under-voltage: to protect against supply line problems.
4. Phase sequence and integrity: to protect against dropped phase faults and wrong phase sequence after reconnection to the grid.
5. Noise and line disturbances: protected against the high-voltage spikes and faults of the industrial environment.
6. Internal temperature: to protect against cooling circuit failure, typically caused by a blocked fan or ventilation inlet/outlet.

• Individually powered, isolated, versatile two input user/control interface.
• Selection of fault handling, trigger/control type, profile, deceleration, starting value and duration, operation timer by DIP switch.
• Galvanically isolated bit outputs ("Idle", "Run", "By-pass", "Fault").
• Load current signal analog output.
• Overcurrent limit can also be set externally via the analog input.
• Small 24 VDC power supply to power a local sensor or other automation device.
• Installation-friendly, robust, space-saving "bookcase" style enclosure.
• Separate control circuit supply to enable separate/isolated power circuit functions and to prevent any power disruptions from affecting the unit's control and monitoring functions.

The individual model characteristics are summarized in the following table:

Units above 90 HP and for non-standard or medium voltage applications are offered on a custom, per order basis.

The NSFT/ICCD panel controller accessory enables the NSFTxx to operate in a Quamatic or similar network as well as integrating all the functions required for local operation.
 

The line is also available in ready-to-install, completely assembled systems. Units over 10HP include a bypass contactor to minimize heat dissipation.

Features are:

• The IP54 electrical wall-mounted cabinet is designed for use in an environment of <50 deg.C.
• The front NSFT/ICCD panel controller features a polyester membrane, carries the indicating LEDs, the two start/stop switches and the bypass contactor solid-state switch. Network connectivity is offered as an option.
• The bypass contactor is driven by the panel controller's solid state switch.
• A 400/230 V transformer sources the required 230 V control voltage thus eliminating the need to connect to the line neutral.
• Line and load connections are made to DIN rail terminal blocks.

Other soft starter products of interest:

• The BSxT basic soft starter addresses simple and low cost applications such as hydraulic lift pumps and ventillation fans.
• The iSFT intelligent soft starter controller is recommended for more complex and demanding soft starting applications.
• The solid state relay analog controller can be used to start a single phase motor load.