Motor Controller Types and Operation:
Inside the two basic types of motor controllers, there are three main categories of AC across the- line controllers in use presently. There is LVP (low-voltage protection), LVR (low-voltage release), and low-voltage release effect (LVRE) controllers.
The main purpose of an LVP controller is Figure 12 LVP Controller to de-energize the motor in a low voltage condition and keep it from re-starting automatically upon return of normal voltage.