Lots of processes involve motors being loaded and unloaded almost continuously.
Examples include.... rolling mills of all sorts, web-processing, mines, large hoists, and auto shredders, just to name a few.
Some of these processes use DC drives, some use AC motors. While the internal operating differences are significant, the power system impacts are the same.
- Each process has significant regular changes in the mechanical power required to perform the intended work. Squeezing a cold metal sheet alternates with idling. A miner digs into a seam, then "backs out" and repeats the process again. An auto shredder accelerates a huge hammer mill to pulverize a car, then re-accelerates it once the cart is past.
- The mechanical power comes from electrical power, and the electrical loading changes (AC motors and inverters) distorts and increases the mechanical power requirements because of swings in real and reactive power demand.
These swings always cause significant loading swings on the plant power bus. A Dynamic VAr System can used to:
- Cancel VAr flow on the plant bus. This reduces power flow through cabling, switchgear, and transformers by levels of 30% or more, depending upon the application. In turn this can reduce equipment sizes and required switchgear ratings while extending equipment life.
- Reduce DC drive hunting due to voltage swings, especially critical for modern high quality mill products.
- Maximize AC motor torque, directly increasing output in mining, auto recycling and similar AC motor applications.