Overvoltage and overcurrent protecting circuit

Abstract

The present invention discloses an overvoltage and overcurrent protecting circuit connected between a power source and a load, which includes: a resettable fuse, a first end of which is electrically connected to an output end of the power source; a switch circuit, a first conduction end of which is electrically connected to a second end of the resettable fuse, and a second conduction end of which is electrically connected to the load; an overvoltage circuit, for detecting whether an output voltage of the power source is overvoltage; an overcurrent detecting circuit, for detecting whether a current flowing through the resettable fuse is overcurrent; and a switch control circuit, a first input end of which is electrically connected to an output end of the overvoltage detecting circuit, and a second input end is electrically connected to an output end of the overcurrent detecting circuit, to control the electrical connection between the output end and the control end of the switch circuit, so as to control disconnection of the switch circuit when the overvoltage and / or overcurrent is detected, and automatically control the conduction of the switch circuit after a preset time period for disconnection is reached. The circuit of the present invention can protect the overvoltage and overcurrent at the same time, and can recover normal operations of the load after the fault state is vanished.

Description

technical field [0001] The invention relates to a protection circuit, in particular to an overvoltage and overcurrent protection circuit. Background technique [0002] Power load management terminals have been widely used in the field of power automation. Power load management terminals are usually installed in various factories and mines. In practical applications, the main control station of the power company sends various commands to the power load management terminals located in various factories and mines through its omnidirectional antenna, and the power load management terminal Extract the data from the response code. [0003] Power load management terminals need to withstand various electromagnetic interference from transformers and power grids, so electromagnetic compatibility measures have been taken to protect the terminals from being disturbed and still work normally. One of the serious interference situations is that the interference affects the terminal power...

AI Technical Summary

Problems solved by technology

[0005] 1. The recoverable fuse relies on current trigger protection, and does not provide protection before the overvoltage state does not cause overcurrent;

[0006] 2. After entering the protection state, if there is still residual voltage and residual current in the internal circuit system, the internal circuit system may enter an abnormal state and cannot recover by itself.

It may cause the resettable fuse to fail to return to the conduction state after the external interference is removed, so that the terminal cannot resume normal operation

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