Apparatus and method for measuring direct current branch insulation resistance utilizing unbalanced bridge

Abstract

The invention relates to an apparatus and method for measuring direct current branch insulation resistance by unbalance electric bridge which comprises CPU unit, inlet signal circuit, outlet circuit, analog value input circuit and digital-analog converter. Outlet signal circuit is connected with one end of bar coupler to quote weather the bus is parallel running or segment running; the unbalance electric bridge of analog value input circuit is parallel connected with bus and can uses resistance divider to change voltage signal into weak voltage signal analog switch gating and inputs in into CPU unit by digital-analog converter; the signal collecting circuit of analog value input circuit is connected with voltage signal output end of branch inspecting sensor and inputs the voltage signal into CPU unit by eclectic switch gating and digital-analog converter; CPU unit controls the opening and closing of outlet contact by outlet circuit.

Description

technical field [0001] The invention belongs to the technical field of relays, in particular to a device and a measurement method for measuring the insulation resistance of a DC branch circuit by using an unbalanced electric bridge. Background technique [0002] In order to ensure the safe operation of the power system, the working power sources such as protection devices, relays, and trip switches in power plants, substations, substations, and switching stations all use DC power sources with battery energy storage. The power supply is insulated from the ground. When the DC feeder is grounded at one point, it will not affect the normal operation of the system, but the grounding point must be found in time to eliminate the fault. Otherwise, when the second point is grounded, the relay or protective device may malfunction and cause a major accident. [0003] Due to the complex wiring and many branches of the DC system, it is difficult to judge the faulty line of the ground. ...

AI Technical Summary

Problems solved by technology

However, this detection method can only determine the faulty branch, and cannot calculate the insulation resistance of the positive and negative feeders.

In addition, there is also the problem of detecting the dead zone. When the positive and negative insulation is reduced at the same time and the resistance is the same, the total current flowing through the transformer is 0. At this time, the fault cannot be judged from the leakage current value.

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