Purvis Industries

THE BENEFITS FROM ELECTRIC MOTOR BRAKING

          Many of our customers have the need for electric motor braking whether they know it or not. Most of them are unaware of the potential time and energy savings they could receive from electric motor braking.

          Once it has been determined braking is required there are several things that need to be known. The first thing that must be known is the weight and speed of the rotating load, next is how fast that load needs to be stopped and lastly how frequently this load needs to be stopped. Once these factors are known it can be determined if the VFD drive can stop the load on its own or if additional items are required. In the event the VFD drive needs additional items to stop the load you might need to add a braking resistor and or the brake chopper option to the VFD drives order code. On some occasions you will need to add an external brake module to a VFD drive that doesn’t have the option for a brake chopper. These items are used together to dissipate the excess energy that is created when stopping a rotating load.

           The most common solution is to dissipate this energy by turning it into heat with a braking resistor. Braking resistors have a duty cycle and come in varying wattages and resistances. They can only be on for a certain amount of time and will require more time off to cool down.

On applications that stop frequently or that create an excessive amount of power it is recommended to use a regenerative unit or a regenerative VFD drive. This solution turns this excess energy into electricity that can be used elsewhere in the customers plant. While this solution is more expensive to purchase initially it’s cost can be recovered by the energy savings it creates for the customer.

Your Regional Triad Application Engineer can assist you and your customer in the decision of a braking resistor or a regen unit for their application.