Cruise Control for Your Motor

Cruise Control for Your Motor

Today you are leaving for vacation – a little spot you found just a few hours away. It is early in the day, the roads are open, and the weather is great. 

You turn on the cruise control: there is no need to keep your foot on the pedal to keep the car moving. You let the electronics and mechanics of the vehicle do all the work. Now you can relax and enjoy the drive!

Using a bypass contactor with your soft starter is very similar. 

The soft starter starts the motor, and after it is up to speed, it transitions control over to the bypass contactor, allowing the motor to continuously run at full speed.

This is like cruise control for your soft starter. After the bypass contactor is activated, you can sit back and let the process run!

Today, many soft starters have an internal bypass contactor. These are hybrid soft starters, meaning they have the power structure of a solid-state starter and an internal bypass contactor. 

With an integral bypass soft starter, you need only power and control wiring, there is no need to purchase any additional devices. Integral bypass on a soft starter is ideal for conveyors, fans, pumps and other applications where the current and speed do not need to change while the motor is at speed.

Advantages of an integrated bypass are:

  • Smaller footprint  
  • Reduced wiring
  • Less heat dissipated
  • Lower total install cost  

If your soft starter does not have an internal bypass contactor, you can add an external bypass contactor. The external bypass contactor can either be NEMA or IEC rated, depending on the need and requirements of the application. These fully solid-state soft starters are well suited for harsh, dusty, vibration prone applications.

Advantages of an external bypass are:

  • Allows for specialized control  
  • Higher operations per hour
  • Longer life, no mechanical life limitations
  • Ideal for critical performance in harsh environments

How do you know when to use an internal versus external bypass contactor? 

For more detailed information on bypass control, please download our Soft Starter Bypass Technology in Smart Motor Controllers white paper.

Bill Bernhardt
Posted August 22, 2016 By Bill Bernhardt, Senior Commercial Engineer, Rockwell Automation
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