Output channel leakage current detection circuit

Abstract

The invention discloses a leakage current detection circuit for an output channel. The circuit comprises a leakage current detection resistor, a normal current output voltage stabilizing tube, a detection circuit threshold value regulation voltage stabilizing tube, a detection circuit current limiting resistor and a detection output isolation device, wherein the leakage current detection resistor is connected in series with a loop of the output channel; the normal current output voltage stabilizing tube is connected in parallel with the leakage current detection resistor; and the detection circuit threshold value regulation voltage stabilizing tube, the detection circuit current limiting resistor and the detection output isolation device are connected in series, and then are connected in parallel with the leakage current detection resistor. The circuit is simple in design; only a few sorts of elements are adopted, so that the circuit is low in cost; the circuit is small in size (occupies a small area), and is suitable for a multi-output channel system; a leakage current detection threshold value of the circuit is easy to regulate; the sensitivity of the circuit to milliampere-level current can be regulated by regulating the voltage stabilizing tubes and the resistors; the partial voltage of the circuit for an output circuit is determined by stable voltage values of the voltage stabilizing tubes and the positive working voltage of an optocoupler; and when a trunk line normally outputs heavy current, the maximum voltage drop of the trunk line cannot exceed the stable voltage values of the voltage stabilizing tubes.

Description

technical field [0001] The invention relates to the technical field of electronic circuit design, in particular to an output channel leakage current detection circuit applied to industrial control systems, safety signal systems and other systems. Background technique [0002] In industrial control systems and safety signal systems (applied to avionics, railway signals, nuclear power and other industries), the control of the controlled equipment by the system is usually completed through the output channel, and the controller realizes the external controlled signal by switching the output channel. on and off. [0003] Such as figure 1 As shown, it is a common design structure of an output channel circuit, which is composed of three parts: a controller 1, a solid state relay 2, and a leakage current detection circuit 3. Since the solid state relay 2 has a potential failure mode with a smaller off resistance. In this failure mode, even if the output channel is closed, there ...

AI Technical Summary

Problems solved by technology

At present, known leakage current detection circuits (such as current induction coil leakage current detection circuits, etc.) often have disadvantages such as complex circuits, large volume (or area), and high cost.

At the same time, when the main circuit outputs a normal current, some leakage current detection circuits still have the disadvantage of a large voltage divider for the normal output voltage.

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