SMC3 Controller

The SMC3 controller is designed for smooth starting and reliable operation of single and three-phase AC induction motors. It offers various features to optimize motor performance and protect connected equipment.

Dimensions

• Size 1: 45 mm wide, three-phase control enabling a real soft start capability up to 20 kW
• Size 2: 72 mm wide, three-phase control enabling a real soft start capability up to 45 kW

Features

The SMC3 controller boasts several key features:

• Integrated DIP switch; electronically selectable overload protection (trip class 10, 15 or 20)
• Adjustable overload setting via rotary dial
• Integrated bypass
• Designed for complete integration with the Allen-Bradley MCS range
• Seven nominal ratings ranging from 3 A to 37 A
• Two control voltage options: 24 Vac / dc and 100 V to 240 Vac. 50/60 Hz over 0 to 40 °C

Starting and Stopping Methods

The SMC3 offers flexible starting and stopping methods:

• DIP switch, selectable start methods: soft start of 2 to 15 seconds, current, limit, manual start
• Selectable stop methods with DIP switch: smooth stop at 100%, 200% or 300% of the starting time, inertia until stop

Protection Features

The SMC3 incorporates various protection features to ensure reliable operation:

• Phase rotation check
• Fault detection: phase loss / open line / load loss, SCR short-circuited, gate open, excess temperature - power section
• Phase unbalance: 15% of the line value, overload, phase reversal - pre-start only

Indicators

The SMC3 features LED indicators for:

• "Connection" status
• Fault indication

Important Note

Nominal kW values are based on the 350% current limit value. The product should always be selected based on the full load current of the motor.

Allen Bradley Soft Starters

Allen Bradley soft starters were developed to overcome the drawbacks of direct on line (DOL) and star-delta starting of single and three phase a.c. induction motors, such as high starting currents, voltage peaks and mechanical snatch. Soft starters achieve these benefits by controlling the voltage applied to the motor at starting, giving a reduced but controlled starting current and torque to meet the requirements of the motor-driven load. From this starting value the voltage is gradually increased to full value via adjustable ramp times.

Applications

Typical applications that would benefit from the use of soft starters include:

• Conveyor belts
• Pumps
• Mechanical handling equipment
• Air conditioning systems
• Compressors
• Grain dryers
• Fans

Advantages

In addition to the above, the installation of a soft starter provides the following major advantages:

• Reduced starting torque minimizing stress on motor, bearings, drive belts and chains
• Prolonged equipment life and reduced maintenance
• Minimizes voltage dip problems which may affect sensitive electronic equipment on site
• Energy saving through reduced peak kVA
• Allows minimum cable conductor size
• Elimination of high current transients: when a 3-phase motor switches from Star to Delta