QDB-101DC 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:

QDB-101DC Grounding Intelligent Quick Finder

2.2 Device principle

2.2.1Principle of DC Crossover Search

The system analyzer is connected to the two DC busbars being tested, and a detection bridge is switched to one of the busbars. The voltage change waveforms of the two busbars are compared to determine whether there is a ring network fault or insulation fault in the system based on the voltage change relationship. If there is a ring network fault or insulation fault, the detection bridge is continuously started for the branch detector to locate the ring network fault point.

When there is a ring network fault in two branches, a detector and collector can be used to detect each branch that may have a ring network fault one by one. Based on the waveform and direction displayed by the detector, the final search for the ring network fault point can be achieved.

The schematic diagram of DC crosstalk detection is as follows:

2.2.3Principles of AC surge detection

The system analyzer is connected to the tested DC bus and detects the AC voltage component in the DC system in real time. If the AC voltage component in the DC system exceeds the set value, it is determined that there is an AC surge fault in the DC system.

The process of finding the fault point of AC surge is the same as the process of finding the insulation fault point.

3、 Functional Features

3.1 Introduction to Main Functions

（1）The system has the function of measuring ground voltage, and the instrument can measure the system's positive ground voltage, negative ground voltage, and system voltage, which can be achieved0—300VThe voltage monitoring range;

（2）System insulation impedance measurement function, the instrument can measure the system's positive to ground insulation impedance, negative to ground insulation impedance, and balance bridge size detection,measurement range0—999.9KΩ；

（3）The AC surge detection function allows the instrument to detect AC surge faults in the DC system and measure the AC voltage value entering the DC system. The AC voltage measurement range is0—280V；

（4）System distributed capacitance measurement function, the instrument can measure the distributed capacitance of the system and display it in real time;

（5）Ring network detection and positioning function, the instrument can detect various ring network faults in two sections of the busbar, including positive pole ring, negative pole ring, two pole ring, and opposite pole ring, and can locate the ring network fault point through waveform display and direction display;

（6）The device has functions of amplitude modulation, reset, current waveform selection, and working mode selection, which can achieve the search and location of high resistance ring network faults.

（7）Branch insulation impedance measurement and insulation fault location function, the instrument measures the insulation impedance of each branch to ground, and can locate the insulation fault point through waveform display and direction display;

（8）Fault current spectrum analysis function, the device can quickly analyze the fault current spectrumFFTTransform the frequency spectrum analysis function to achieve current changes, effectively extract the signal amplitude of the measured current frequency point, and improve detection accuracy;

（9）The ammeter function allows the device to be used as a high-precision ammeter, with a current measurement resolution of up to0.01mA;

（10）The waveform curve display and direction display function, when using the detector to detect the measured branch, the display screen will display the current change of the measured branch in the form of waveform curve, which is convenient for users to quickly and accurately find the fault point,Display the direction of the fault point when there are ring network faults and grounding faults.

3.2 Equipment Features

（1）High reliability design

The device is imported32The microcontroller serves as the main system, and the hardware design strictly follows the relevant standards of power and electromagnetic compatibility. Multiple redundant methods are used internally to ensure the reliability of the device and the tested equipment.

（2）Precision material selection

The device uses a high-precision collector as the signal acquisition unit, and the voltage sampling adopts a high-precision imported analog-to-digital conversion chip, ensuring accurate measurement of voltage and impedance;

（3）Humanized human-computer interaction interface

Both the "analyzer" and "detector" useTFTLCD display screen for users to view information;

The operation is simple and fast, and when detecting different branches, only one press of the start button is needed to complete it;

The test results are displayed intuitively and clearly, and can be presented to users in various display forms, including grounding status, waveform curve, insulation level, insulation impedance, leakage current size, direction information, etc.

（4）Intelligent detection and recognition system

The analyzer can automatically identify the system voltage level;

The analyzer can determine the category of ring network faults;

After synchronizing the information of the "detector" and "analyzer" once, it is not affected by the detection distance;

When the "detector" is used for detection, the collector can clamp a single power cord or multiple power cords to improve detection efficiency;

After the "detector" completes the detection, if there is a ring network or insulation fault in the tested branch, it will determine the direction information of the fault point relative to the test point.

（5）Complete testing functions and fault handling capabilities

The "analyzer" and "detector" are equipped with wireless data transmission modules for communication, with complete testing functions and display information, and can handle various ring network and insulation fault situations in DC systems.

“analyzer”possessMultiple combination working mode selection functions of "amplitude modulation", "waveform", and "mode" can adapt to various complex application environments.

（6）高安全性

The device uses microampere level detection signals combined with high-resolution DC detection collectors to achieve fault detection and localization, without any impact on the DC system.

4、 Main technical indicators

4.1 Main technical indicators of the analyzer

Usage environment

lWorking power supply:DC22V-300V,

lAmbient temperature-20℃—55℃

lRelative humidity:0—90%

DC voltage measurement

lDC voltage measurement range:22-300V

lResolution of DC voltage measurement:0.1V

lAccuracy of DC voltage measurement:220V DC power supply system (180V~286V) 110V DC power supply system (90V~143V)±0.5%

AC voltage measurement

lMeasure AC and DC surge voltage:10-280v

lAC voltage measurement resolution:0.1V

lAccuracy of AC voltage measurement:±5%

Insulation resistance measurement

lMeasurement range of insulation resistance:0-999.9KΩ；Resolution of insulation resistance measurement:0.1KΩ

lMeasurement accuracy of insulation resistance:Ri < 10KΩ Display specific numerical values

10KΩ≤Ri≤500KΩ ±5%

Detection bridge amplitude adjustment range:0mA，0.25mA，0.5mA，1mA，2mA

lRange of resistance values for the detection ring network:50KWithin Ω

System distributed capacitance measurement

Measurement range of system distributed capacitance:0-999.9uF Accuracy C<10uF or C>200uF: Display specific values; 10uF≤C≤200uF:±10%or±3uF；

Selection of waveform types for detection: sine wave, square wave；

lbeUnified ground capacitance measurement:0－1000kΩ

Selection of waveform types for detection: sine wave, square wave

Working mode: forced signal start, automatic signal start

Display medium and resolution:TFT,320x240

4.2 Main technical indicators of the detector

Insulation resistance measurement

lMeasurement range of insulation resistance: 0-500KΩ

lResolution of insulation resistance measurement:0.1KΩ

lMeasurement accuracy of insulation resistance:Ri <10KΩ Display specific numerical values

10KΩ≤Ri≤500KΩ:±10%

Spectrum analysis scope

lNumber of channels for spectrum analysis:1

lSpectrum analysis frequency range:0.125-12.5Hz

lfrequency resolution: 0.125Hz

Current waveform display period:8s；

Detectable feeder current range:0—2A；

Current measurement range:-100—+100mA；

Current measurement resolution: 0.01 mA

Display medium and resolution:TFT,320x240

4.3 Wireless Communication Technology Indicators

lSpeed:2Mbps， Due to the short transmission time in the air, the collision phenomenon in wireless transmission is greatly reduced

lMulti frequency points:125 frequency points, meeting the needs of multi-point communication and frequency hopping communication

lUltra small: Built in2.4GHz antenna, compact size, 15x29mm

lLow power consumption: When operating in response mode communication, fast air transmission and startup time greatly reduce current consumption.

fivePrecautions

（1) Due to the fact that the device is a precision instrument, it should be handled with care during transportation, use, and storage. All components should be protected from strong vibrations such as dropping and falling to ensure high precision during use.

（2) Before each detection after turning on the detector, there should be a data synchronization between the detector and the analyzer. During synchronization, the distance between the detector and the analyzer should be kept within 5 meters. After data synchronization is completed, the detector can be kept away from the analyzer, but when using, please keep the detector turned on after data synchronization.

（3) After each use, the battery of the detector should be removed from the battery compartment and fully charged for the next use. When the detector's battery is low, the battery should be replaced immediately to ensure smooth testing.

（4) The analyzer must be connected before the tested branch (according to the current flow direction), with the positive, negative, and ground wires respectively connected to the DC positive bus, negative bus, and ground wire to ensure good grounding of the ground wire.

（5) Due to the high sensitivity of the collector, it should be kept in a stationary state during detection to avoid affecting the accuracy of the detection.

（6) DetectoruseDtypeDuring collector detection,If it appearsPlease ensure that the current of the measured branch does not exceed 1A, as indicated by the phrase 'clamp meter saturation'. If it exceeds this value, please clamp both positive and negative wires.

（7) Due toDtypeThe collector adopts a staggered process of teeth. When in use, the collector should be opened and the wire clamped. The collector should be closed naturally. If it cannot be closed naturally, it should be carefully observed and closed without external force. If it is forcibly closed, it will cause the teeth on the jaws to be misaligned and not tightly closed, damaging the collector.