TH-CZ01 DC Grounding Fault Detector

TH-CZ01 DC Grounding Fault Detector

I. Overview

DC system in power systemGrounding fault is oneEasy to breedA fault that poses a significant threat to the power system. Whether it is positive or negative grounding, it may cause protection misoperation or protection refusal, endangering the normal operation of the power system.

The Electric Power Industry Standards of the People's Republic of ChinaDL/T856－2004How to translate

The setting values for grounding faults in different DC systems are specified. When the grounding impedance of the DC system is lower than this resistance value, it indicates that the system is in a faulty operating state and needs to be dealt with as soon as possible.

due toThe complexity and dynamism of DC systems often make it difficult to locate DC grounding faults, and traditional pulling methods are no longer sufficient to locate grounding fault points while ensuring safe system operation. In recent years, relevant regulations have explicitly prohibited the use of pulling methods to locate grounding fault points.In order to assist on-site maintenance personnel in quickly and accurately identifying grounding fault points, our company has developed a portable DC grounding fault locator through years of effort and extensive on-site experience. This locator can find and solve various voltage levels（

48V，110V，220V）Indirect grounding, non-metallic grounding, loop grounding, positive and negative simultaneous grounding, positive and negative balanced grounding, AC/DC surge faults, multi-point grounding and other insulation faults in DC systems.The portable DC grounding fault locator adopts a high-resolution sensing unit to collect the leakage current of the grounding point in the DC systemDetect 600K at 220V voltage levelΩ

The internal insulation impedance to ground has fast detection speed and accurate positioning,

Truly solved the insulation fault problem in DC systems.2、 Working principle

Portable DC grounding fault locatorThe basic principle is to use the leakage current signal of the grounding point. When an insulation abnormality occurs in a certain feeder circuit of the DC system, a leakage current related to the resistance value will be generated in the insulation impedance of the branch to ground, as shown in the following figure:

From the above figure, it can be seen that when the negative pole experiences an insulation anomaly with a ground impedance of Rx, the current magnitude at point A (the vector sum of the current magnitude of the positive and negative power lines supplying the load RL) is:；

Portable DC grounding fault locator

By analyzing the system's ground voltage and the leakage current of each branch, the insulation condition of the system and the insulation fault points of the branches can be determined.When detecting above the grounding point, an insulation fault signal will be given; When detecting below the grounding point, a normal insulation signal will be provided to locate the grounding fault point.

Portable DC grounding fault locator

It consists of two parts: the "analyzer" and the "detector". When in use, connect the power cord of the DC system insulation analyzer to the positive pole, negative pole, and ground wire of the tested DC system bus according to the markings. After turning on the power, the analyzer will analyze the insulation condition of the DC system and display parameters such as the direct to ground voltage, negative to ground voltage, and grounding impedance on the instrument LCD screen. If insulation abnormalities are detected in the system, users can use the detector to locate the grounding point.

The analyzer and detector can communicate data through a wireless module. The detector is equipped with a high-resolution collector to detect the leakage current of the measured branch. At the same time, it reads the ground voltage signal transmitted by the insulation analyzer through the wireless module, and detects the insulation impedance of the measured branch based on the voltage and current values.

1TH-CZ01 DC Grounding Fault Detector

3、 Functional Features1Introduction to main functions0（）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 achieved—

300V2The voltage monitoring range;0（）System insulation impedance measurement function, the instrument can measure the system's positive to ground insulation impedance and negative to ground insulation impedance, and can achieve—

999.9K3Measurement of Ω;0（）The AC surge detection function allows the instrument to detect AC surge faults in the DC system and measure the AC voltage value in series with the DC system. The AC voltage measurement range is—

280V4；

（5）Branch insulation impedance measurement function, the instrument measures the positive and negative to ground insulation impedance of each branch;

（6）The branch grounding fault point positioning function can be achieved by the instrument, which can locate the grounding fault point of the branch grounding fault;（

）The ammeter function allows the device to be used as a high-precision ammeter, with a current measurement resolution of up to70.01mA;

（8）The device has the function of non signal grounding search, and can locate the grounding fault point without injecting any signal into the system;

（9）The direction display function will provide directional arrows to indicate the relative direction between the grounding point and the searched grounding point for the tested branch, improving search efficiency.

（10）The insulation index analysis function, when using the grounding function for testing, after detecting a branch, the detector will display the insulation index of that branch for user reference and analysis.

2（

）The waveform curve display function, when using a detector to detect the insulation condition of the tested branch, the display screen will show the current changes of the tested branch in the form of waveform curves, making it convenient for users to quickly and accurately locate the fault point.1Equipment characteristics

（16）High reliability design

The device is imported2The 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.

（

）Precision material selection3The 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;

（

）Humanized human-computer interaction interface

Both the "analyzer" and "detector" use LCD screens 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;4The 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.

（

）Intelligent detection and recognition system

The analyzer can automatically identify the system voltage level;

The analyzer can quickly display insulation impedance information after the system insulation impedance changes;

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 line or multiple power lines to improve detection efficiency;5After the "detector" completes the detection, if there is an insulation fault in the tested branch, it will determine the direction information of the fault point relative to the test point.

（

）Complete testing functions and fault handling capabilities6The "analyzer" and "detector" are equipped with wireless data transmission modules for communication, with complete testing functions and display information, and can handle various insulation fault situations in DC systems.

（

）高安全性

The device can locate the grounding fault point without injecting signals into the DC system. In signal mode, the device is equipped with a current and voltage limiting module, which has no impact on the DC system.14、 Main technical indicators

（）Usage environmentl

Ambient temperature-30℃～+50℃；l

relative humidity2≤95%；

（）Wireless communication technology indicatorsl

Signal power:≤ 10dbm；l

Signal frequency band:433Mhz；l

Sensitivity: -106dBm；l

Transmission distance: at line of sight, above ground2 meters reliable transmission distance 250 meters

(3)Technical specifications of analyzer l

Applicable DC system voltage level:48V, 110V, 220V or user specified voltage levell

System positive and negative voltage measurement range:0—300Vl

Measurement range of DC voltage to ground:0—300Vl

Measurement range of AC voltage to ground:0—280Vl

Alarm threshold for AC surge fault:5Vl

Voltage measurement resolution:0.1Vl

Measurement range of system to ground resistance:0—999.9KΩl

Ground resistance measurement resolution:0.1KΩl

Display mode:LCDl

Detecting signal current magnitude:0-2mA adjustablel

Detecting signal voltage amplitude:0-50V adjustablel

Signal frequency: No signal mode and0.16Hz optionall

Anti DC system distributed capacitance interference:1000uF

(4)Technical specifications of the detector

lDetection range of branch insulation impedance in signal mode:

The system voltage level is220V：　0 -600KΩ

The system voltage level is110V： 0 -300KΩ

The system voltage level is48V：　 0 -60KΩ

Resolution of insulation impedance measurement:0.1KΩ

lDetection range of branch insulation impedance in no signal mode:

The system voltage level is220V：　0 -50KΩ

The system voltage level is110V： 0 -25KΩ

The system voltage level is48V：　 0 -10KΩl

Resolution of insulation impedance measurement:0.1KΩ 12l

Waveform display time:secondlCurrent measurement range:

±100mAl

Current measurement resolution:0.01mAl

Display mode:LCD

lDirection display mode: same direction or reverse indicationl

Anti DC system branch distributed capacitance interference:100uF

lDistance between the analyzer and the user: No distance limitlJaw size:

F

130mm

5、 Usage method

Equipment appearance and description of each functional key2. Operation method

（

1) The analyzer is connected to the DC systemTurn off the power switch of the analyzer, insert one end of the power cord configured with the device into the analyzer, and connect the other end to the positive, negative, and ground wires of the DC system according to color.

Brown: positive electrode; Blue: Negative pole; Huang

/Green: GroundAfter confirming that the wiring is correct, turn on the power switch and enter the main interface of the analyzer, as shown in the following figure:

After turning on the power switch, the power indicator light of the analyzer lights up and automatically identifies the system voltage level, determines whether there is an AC surge fault in the system, calculates the system insulation impedance, and displays itOn the LCD, if the system insulation is normal, the normal indicator light is on. If abnormal insulation of the system to ground or negative ground is detected, the positive or negative ground alarm indicator light is on.（

2）Self-test of detector

Translate into EnglishPlace 4 No. 5 batteries into the detector battery compartment as indicated, turn on the power switch, and enter the main interface of the detector, as shown below:When the analyzer detects an insulation fault in the system, clamp the detector collector onto the analyzer's ground wire, use the function key to select the detection function as the fault detection function, press the test key to perform the detection, and if the "communication test" appears

…

Please wait "prompt interface, please bring the detector close to the analyzer. After the detection starts, the detector will display a grounding detection waveform diagram. The detection process diagram is shown below:

The downward arrow in the figure is the signal synchronization auxiliary arrow, which appears at the turning point of the waveform from high to low;When the detector detects, it will display two cycles of signal waveform diagrams. The measured waveform diagram may differ from the above figure. As long as the waveform diagrams of the two cycles are displayed correctly, it can be determined that the equipment self-test is normal.

The grounding point direction indicator arrow can reflect the direction of the fault point relative to the test point. The specific judgment method is described in the following section

Introduction to using 'grounding point direction' to detect loop grounding.

Without grounding, the system analyzer will not send any signals to the system, nor will it send synchronization signals to the detector.3 During self inspection, please ensure that there are no other devices in the DC system that are sending signals to the DC system. If there are, please exit the post test, including during the subsequent search process, devices with signal sources must be exited from the DC system, otherwise it may interfere with the detection.

（

）Testing beginsAfter passing the device self-test, the system branches can be tested one by one. To ensure smooth testing, do not turn off the power of the detector when moving it away from the analyzer for testing.

The detector has three functions available for users to use, namely

The three functions of "fault detection", "insulation analysis", and "current detection" can be switched through the function keys.

Fault detection function

The device has set different threshold values for branch grounding impedance detection for different voltage level systems. When the branch insulation fault is less than this threshold value, the detection result displays a grounding fault alarm signal and informs the direction of the grounding fault point;

/K

Ω

Equipment grounding detection threshold table

0-300

0-600

Impedance Measurement Range Table of Detector

If there is an insulation fault in the tested branch, the schematic diagram displayed after the detection is completed is as follows:

Current detection functionThe current detection function will directly display the leakage current of the tested branch in the form of current magnitude. The usage method of this function is as follows:

（1）Place the collector in a natural state (without clamping any current branch and keeping the clamp closed normally), select the function item through the function menu, and press the test button to enter the display interface of the function item;

（2）Clamp the collector into the tested branch, and the leakage current of the tested branch will be displayed on the screen; As shown in the current detection function 1 in the following figure;

（3）In the current detection function display interface, press the "Test" button to reset the current to zero. When detecting the current of the next branch, the collector is in a natural state. Press the "Test" button until the current is displayed as zero on the display screen, and then clamp in the tested branch;

（4）The current detection function display interface will show the status of each branch. When the system analyzer is in "non signal detection" mode, this function can be used to detect the status of each branch. In this mode, the branch status is detected, and the collector can only clamp the positive and negative branches together. The branch status displays three results: normal; Insulation impedance value with direction; Abnormal. Displaying 'abnormal' indicates that the leakage current of this circuit is large, and there may be a possibility of a loop. After the detection is completed, as shown in current detection function 2 in the following figure;

（5）When the system analyzer is in other detection modes, the branch status information is provided for reference. By default, the system analyzer is in signal detection mode.Explanation: The four position dip switch on the side of the system analyzer can be used to set the operating mode of the analyzer. The dip switch is

x998.00—600The default display of the device when it leaves the factory is when it is turned onMode, i.e. unlimited amplitude, limited current

1mA

.996.0Forced signal mode: In forced signal mode, if the system grounding impedance changes, the signal current remains unchanged; In non mandatory signal mode, if the system grounding impedance changes and exceeds a certain threshold value, the analyzer will recalculate the signal current size.

Power-on displayIn mode, the analyzer operates in non signal mode.The limit is represented in the table as“x”

,4 This gear has no limit.

（

）Testing Techniques

Detection method for "single clamp"

If the positive electrode is grounded, clamp the collector onto the positive electrode cable using the same testing method as above; If it is a negative grounding, clamp it onto the negative cable and use the same testing method as above.

Detecting multiple routes together to improve detection efficiency

Clamp the collector onto this bundle of cables (note: the clamp of the collector must be able to close). If the insulation is detected to be normal, it means that there is no grounding fault in the tested bundle of cables; If it is determined through testing that there is an insulation fault in the cable bundle, it indicates that one or more circuits in the tested cable bundle have grounding faults, and the cable bundle must be tested separately.

Explanation of analyzer access point

According to the grounding fault situation of the DC system, connect the analyzer to the positive and negative busbars and ground wire near the output end of the battery. During testing, the analyzer should always be connected to the power supply end of the DC branch, while the detector should always be tested at the load end of the DC branch.(Because there is a balanced bridge inside the analyzer, if it is connected to a certain branch, it will be mistaken for insulation abnormalities when using a detector for searching.)

利用Insulation quantification index "detection for multi-point grounding:The system has multiple grounding faults, or both positive and negative DC busbars have grounding faults. In the detection of each circuit, the device will automatically detect the branch with more serious grounding faults and then detect the grounding fault point. Analyze the test results during the inspection, and identify severe (positive or negative) grounding faults. Can also be utilized“Insulation degree strip”And reference“Insulation degree percentage

”Quantitative index for comparing test results

Minor differences. After the fault is eliminated, other branches should be tested and the grounding fault points should be checked and eliminated one by one.

Determination of grounding direction:The determination of the direction of the grounding point is jointly determined by the direction of the arrow of the collector when the wire is stuck and the direction of the arrow displayed by the detector: taking the direction of the collector arrow as the reference direction, during detection, the direction of the collector remains unchanged. When the direction of the arrow displayed by the detector is downward, it indicates that the direction of the grounding point is opposite to the direction of the collector arrow; When the direction of the arrow displayed on the detector is upward, it indicates that the direction of the grounding point is the same as the direction of the arrow on the collector, as shown in the following figure:

利用

Grounding direction "detection loop grounding:1If one or both poles of two branches in a system are connected together to form a closed-loop system, it is called a loop. Usually, loops appear in the following forms:

（2）The positive and negative poles of the two branches are connected to form a loop;

（3）Connect one of the positive or negative poles of two branches to form a loop;

（

）The positive pole of one of the two branches is connected to the negative pole of the other branch through a load to form a loop.If on-site conditions permit, it is recommended to disconnect the loop connection during testing to improve testing efficiency and reduce testing time. The loop cannot be disconnected or the loop itself is abnormal. In this case, the signal sent by the analyzer will be diverted by the loop, causing the grounding signal to be detected within the loop, resulting in the inability to find the specific direction of the grounding point. The grounding point can be determined based on the direction.As shown in the figure: Branch1 and branch 2 form a loop, while branch 3 is a branch on the loop and has a ground fault. usedetectorrespectivelyA. Five points B, C, D, and E are detected, and the direction indicated by the arrows is the direction of the grounding point detected by the detector. According to the direction of the arrows of the grounding point detected by points A, B, C, D, and E, it can be inferred that the branch where point E is located is a branch of the loop and has a grounding fault

And canFault location. Similar methods can be used for fault location in other types of loop grounding.

利用

Use 'waveform' to determine grounding

The grounding degree of the detected branch can be determined by the waveform: the larger the waveform amplitude, the smaller the grounding impedance of the detected branch; The smoother the waveform, the better the insulation of the detected branch.16、 Precautions

（2）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.5（

）Before each detection after turning on the detector, there should be a signal synchronization between the detector and the analyzer, and the synchronization should be maintained between the detector and the analyzer3Within a distance of meters, after signal synchronization is completed, the detector can move away from the analyzer. When using, please keep the detector turned on after signal synchronization.

（4）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.

（5）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.（）Use of detectorcollectorWhen detecting, ifPlease ensure that the leakage current of the clamped branch of the collector does not exceed the value of "saturation of the clamp meter"

2A6If it exceeds this value, please clamp both positive and negative wires.