QDB-101 DC Grounding Intelligent Quick Finder

I. Overview

DC system insulation fault, DC crossover fault, and AC crossover fault are types of faults that are prone to occur and pose a significant threat to the normal operation of the power system.

In order to better assist on-site maintenance personnel in quickly and accurately identifying DC faults, our company has worked hard for many years, summarized a large amount of on-site experience, and developedDC grounding fault locator.

DC grounding fault locatorBy using a high-precision current clamp meter and utilizing the difference in DC current in the fault circuit for fault detection and localization, the system can quickly identify and locate faultsFFTThe introduction of transformation technology into DC fault finding equipment can detectEach voltage level（24V，48V，110V，220V）Various insulation faults, DC crossover faults, and AC crossover faults in DC systems.

With the increasing demand for safe operation in the power system, the requirements for various types of DC fault detection in the power system will also become higher. Therefore, high-precision and insulation trend analysis will become the new generation of requirements for the power systemDC grounding fault locatorThe basic requirements.

A new type of DC fault based on frequency modulation and amplitude modulation technology baseYuPrinciple of DC current difference detectionnew-typeDC grounding fault locatorIntroducing FastFFTTransformation technology,By analyzingdetection volumeDetailed analysis of amplitude frequency characteristics balances DCgroundingRegarding the safety and sensitivity of fault diagnosisofContradiction, direct currentgroundingFault technology has reached a new heightIt has a wide range of application prospects.

2、 Device structure and principle

2.1 Device composition

DC grounding fault locatorIt consists of three parts: system analyzer, branch detector, and collector, as shown in the following diagram:

2.2 Device principle

2.2.1 Principle of insulation fault diagnosis

The system analyzer is connected to the tested DC bus and uses the ping-pong principle to calculate the balance bridge resistance and ground insulation resistance of the tested DC system. If there is an insulation fault in the tested DC system, the system analyzer inputs a detection bridge with a set frequency and amplitude to the DC system. The detector locates the ground fault point by detecting the current signal in each branch. The detection principle is shown in the following diagram:

The feeder line in the picture1For normal feeders, feedersnFor feeders with negative to ground insulation faults,For insulation fault resistance,RBalance the bridge for the system.

After the analyzer detects an insulation fault, it applies a detection bridge to the DC system, which is shown in the diagramETheFThe input of the detection bridge causes a known frequency periodic change in the DC system's ground voltage. Let the frequency of this change beThe amplitude of the change in ground voltage generated by the DC system is, then flow throughThe amplitude of the current change on top isChange frequency and detection bridge input frequencySame.

The detectors are located separatelyA，B，CConduct testing at the location. atAThe change in current signal cannot be detected at this location, indicating that the feeder line1There is no insulation fault, inBThe change in current signal can be detected at this location, indicating that the feeder linenThere is an insulation fault, butCThe change in current signal cannot be detected, thus it can be determined that the insulation fault point is locatedBTheCbetween.

QDB-101 DC Grounding Intelligent Quick Finder