March 6, 2020

Today the VFD is perhaps the most common type of output or load for a control system. As applications become more complicated the VFD has the ability to control the velocity of the engine, the direction the motor shaft is turning, the torque the engine provides to a load and any other motor parameter that can be sensed. These VFDs are also obtainable in smaller sizes that are price-effective and take up less space.

The arrival of advanced microprocessors has allowed the VFD works as an exceptionally versatile device that not merely controls the speed of the engine, but protects against overcurrent during ramp-up and ramp-down conditions. Newer VFDs also provide ways of braking, power improve during ramp-up, and a number of settings during ramp-down. The biggest savings that the VFD provides is that it can make sure that the engine doesn’t pull extreme current when it begins, therefore the overall demand factor for the entire factory can be controlled to keep the domestic bill as low as possible. This feature alone can provide payback in excess of the cost of the VFD in under one year after purchase. It is essential to remember that with a traditional motor starter, they’ll draw locked-rotor amperage (LRA) if they are starting. When the locked-rotor amperage takes place across many motors in a manufacturing facility, it pushes the electrical demand as well high which often outcomes in the plant spending a penalty for all the electricity consumed during the billing period. Since the penalty may become as much as 15% to 25%, the savings on a $30,000/month electric expenses can be used to justify the buy VFDs for virtually every engine in the plant also if the application might not require operating at variable speed.

This usually limited the size of the motor that could be managed by a frequency plus they were not commonly used. The initial VFDs utilized linear amplifiers to control all aspects of the VFD. Jumpers and dip switches were utilized provide ramp-up (acceleration) and ramp-down (deceleration) features by switching bigger or smaller sized resistors into circuits with capacitors to generate different slopes.

While others have discussed the topic of Variable Speed Gear Motor, my hope is that this post brings an unique perspective.