Phase sequence correcting system for three-phase AC power
US4021704A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 27, 1976 |
| Grant date | May 3, 1977 |
| Priority date | — |
| Expiry date | Feb 27, 1996 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF02B3/06
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The phase sequence of a three-phase AC power supply is detected and information representing that sequence is stored in a memory device, such as a flip-flop. Since the power supply, once it is energized, may require a few seconds to stabilize (such as may be the case when the power source is a diesel generator), the information fed to the memory device is likely to change during the stabilizing period. At the end of that period, however, the stored information represents the true phase sequence of the AC power supply, and at that time the information is read out and used to actuate switching apparatus to interconnect the three-phase AC power supply to the three terminals of a phase-sensitive load (such as a three-phase AC motor) in the manner necessary to provide the load with a desired phase rotation sequence. After the stabilizing period, the input circuitry of the memory device is inhibited so that the stored information representing the true phase sequence will be locked into the memory device and so that the device will be insensitive to any fluctuating voltages, frequency or noise that could otherwise cause an accidental phase reversal while the load is energized.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.