Voltage and phase sequence protection circuit

Abstract

The invention discloses a voltage and phase sequence protection circuit, which comprises a voltage sampling part and a logic control output part, wherein the voltage sampling part consists of two groups of circuits of which each comprises a voltage transformer and a sampling conversion circuit unit; and the logic control output part comprises a microchip module, a resetting circuit module, an oscillating circuit module and an output circuit module. The circuit further comprises a power circuit module and a communication circuit module. The voltage and phase sequence protection circuit provided by the invention simultaneously realizes voltage and phase detection, improves circuit sensitivity, simplifies a circuit structure, can work independently of an independent external power supply dueto structural improvements in the power circuit module, and also can be conveniently connected with other control systems for intelligent control by the communication circuit module, so functions andapplication modes of the circuit are expanded.

Description

technical field [0001] The invention relates to a protection circuit, in particular to a voltage and phase sequence protection circuit for a three-phase electric motor. Background technique [0002] With the development of the economy, motors have been widely used in various industries as a source of electricity and power, so many products for motor protection have been derived, such as simple thermal relays, etc. The action curve of thermal relays is similar to that of motors. The actual protection curves are not consistent, thus losing the protective effect. [0003] In recent years, with the development of technology, some new protection circuits have appeared, such as the attached figure 1 The typical RC-shift phase sequence protector circuit shown in the figure works on the principle of shifting the phase of the three-phase voltage. The phase-shifted circuit is superimposed on the relay RY. When the phase is normal, the relay RY is closed. , the contacts 7 and 8 are c...

AI Technical Summary

Problems solved by technology

Its structural features are simple in the main circuit. It can realize phase loss and reverse phase protection. The disadvantage is that it cannot realize the functions of detecting phase loss (R phase / S phase), voltage imbalance, over-voltage and over-low protection, etc.

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