Composite monitoring device for electrode difference protection and grounding of direct-current system

Abstract

The invention discloses a composite monitoring device for electrode difference protection and grounding of a direct-current system. After one path of the anode and the cathode of a direct-current system passes through a breaker, the anode passes through a Hall current sensor, and the cathode then passes through the Hall drain current sensor; thus, the anode and the cathode simultaneously pass through the Hall drain current sensor to be led out; the other path of the anode and the cathode of a direct-current system directly supplies power to a power supply modifier; after changing high voltage to low voltage, the power supply modifier supplies power to an anode Hall current sensor, the Hall drain current sensor, a cathode Hall current sensor, an MCU microcontroller, a relay, an electromagnet, 485 communication, an alarming port, a fault indicating lamp and a set dialing device through farad capacitor; the anode Hall current sensor, the cathode Hall current sensor and the Hall drain current sensor transfer the detected signals to the MCU microcontroller, and then results are transferred to each above action element after being calculated and analyzed by the MCU microcontroller so as to perform corresponding action.

Description

technical field [0001] The invention relates to a differential protection and ground leakage monitoring device of a DC system, in particular to a comprehensive differential protection and grounding monitoring device suitable for power systems, railway systems with DC 220V or DC 110V, and telecommunication systems with 48V power supply. Background technique [0002] In the power system, when the power equipment is in normal operation, the DC system provides the closing power for the circuit breaker, and also provides the DC power for the relay protection, automatic devices, communication equipment, etc. When a circuit failure occurs in the system, especially when the AC power supply is interrupted, the DC system must provide safe and reliable DC power for relay protection and automatic devices, closing and tripping of circuit breakers, and accident lighting. And the basic guarantee for the correct operation of the circuit breaker. [0003] In the railway system, the signal e...

AI Technical Summary

Problems solved by technology

However, the fuse or DC miniature circuit breaker cannot detect the grounding of the DC system in time, which also leads to the rapid spread and expansion of the accident.

[0007] 1. Limitations of using fuses: fuses use the principle of thermal melting effect to break the fault current, but there are many manufacturers of fuses at present, and the quality of products is uneven. The difference in the materials of fuses and parts cannot fully guarantee the quality of products Therefore, even if the fuses of the same manufacturer and type have certain dispersion, the breaking capacity and ampere-second characteristics of each fuse have certain actual deviations, and the function of differential protection cannot be completed, and the DC system Grounding cannot be monitored in time

[0008] 2. Limitations of using miniature circuit breakers: The circuit breaker uses a combination of magnetic effect and thermal effect, and there is also the problem of inconsistent ampere-second characteristic curves; some manufacturers can only achieve DC positive or negative unilateral protection; When it is too large to a certain extent, the two actions are close to each other, which will cause leapfrogging; even if the DC circuit breakers produced by the same manufacturer, the same model, and the same batch, the ampere-second characteristics are not consistent, and the difference in current and time is very small; the circuit breaker The inherent action time of the circuit breaker is inconsistent, the inherent action time is not marked on the nameplate of the circuit breaker, and it cannot be guaranteed that the inherent action time of the superior circuit breaker is not less than the inherent action time of the lower level; in addition, the current and time differential of the circuit breaker cannot be set; the differential protection of the DC system cannot be completed. and ground monitoring function

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