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FAQ

  • What kind of certificate can you provide

    We can provide CE mark,ISO 9001 quality certificate, the third party calibration certificate(CNAS),factory test report.
  • How to treat the role of DC resistance tester

    The DC resistance measuring instrument determines the welding and connection quality of the lead wire in the closed loop circuit, whether there is a short circuit or open circuit between the turns of the transformer coil, whether the tap switch is in good contact, etc., by detecting the resistance value of the DC resistance. The measurement of the DC resistance of the transformer is an indispensable test in the handover test and preventive test of the transformer.

    The DC resistance measuring instrument is used to measure the DC resistance value of power transformers. The DC resistance value of the transformer has great reference value before entering the transformer maintenance, leaving the factory, and using it. Therefore, the DC resistance measuring instrument is a highly practical device. Professional equipment for measuring the DC resistance of transformer windings and high-power induction equipment.
     
       The DC resistance test of transformer windings is an indispensable test item after transformer handover, overhaul, and tap changer change. In the transformer handover, major repair, minor repair, joint position change, fault inspection and preliminary test, how to measure the DC resistance of the transformer windings, how to treat the role of the DC resistance tester?
     
       1. Check the welding quality of the wires and leads inside the winding
       2. Check whether the contact of each position of the tap changer is good
       3. Check whether the winding and lead wire are broken.
       4. Check the correctness of the parallel branch circuit, and check whether the windings wound by several parallel wires are broken in one or more places
       5. Check whether there is a short circuit between layers and turns.
     
       DC resistance measuring instrument adopts new power supply technology, has the characteristics of rapid measurement, small size, convenient use and high measurement accuracy. It is an ideal equipment for measuring the DC resistance of transformer windings and high-power induction equipment.
  • How to choose the current value of the DC resistance tester?

    The DC resistance tester is a high-precision replacement product that replaces the DC single and double-arm bridges. The instrument adopts advanced switching power supply technology and liquid crystal display measurement results. It overcomes the shortcomings of other similar products that the LED display value is inconvenient to read under the sun, and it also has an automatic arc suppression function.
    This instrument has the advantages of fast measurement speed, high precision, intuitive display, strong anti-interference ability, small size, low power consumption, stable and reliable test data, and not being affected by human factors. The DC resistance tester can quickly measure the DC resistance of the transformer. DC resistance testers include 10A, 20A, 40A, 50A, 100A and other specifications. How to choose a DC resistance tester with a suitable current size? This article will introduce several calculation formulas and explain how to determine the current value of DC resistance measurement.
     
      1, Formula one
       When the AC no-load current at the rated voltage passes through the transformer windings, there will be a rated magnetic flux density Bn in the iron core, and the magnetic permeability of the iron core will be relatively low at this time. When measuring DC resistance, it is necessary to make the magnetic density in the iron core larger than Bn, so that the iron core conductivity becomes lower, so as to reduce the time constant of the circuit and the back electromotive force dLi/dt, and shorten the stabilization time. Therefore, the DC current when measuring DC resistance should be at least:
     
      I=k√2i0In+100
     
      " in the formula:k: constant>1;I0: AC rated frequency, percentage of no-load current under rated voltage (%);In: the rated current of the winding under test (A)"
       where the constant √2 is the magnitude of the DC current equivalent to the AC current. When the factor k is greater than 1, the magnetic density in the iron core> Bn, which reduces the magnetic permeability μ of the iron core during DC resistance measurement.
     
      2, Formula two
       When the transformer windings are connected in star (Y), the line current is equal to the phase current. From the above formula, the current that should be applied when measuring the DC resistance is:
     
      IY=1.41ki0In:100
     
      3, Formula three
    When the transformer winding is triangular (D) connection, the no-load current line current of the converter is √3 times of the phase current, and the DC current when measuring the DC resistance is based on the ratio of the total current] and 1/3 and 2/3 distributed. Therefore, the current should be added to measure the DC resistance:
     
      ID=1.41x3/2+1/√3ki0Inx100=1.22ki0In÷100
     
       When k is 3~10, that is, when the excitation ampere-turn when measuring DC resistance is 3~10 times of the no-load current ampere-turn, you can make the magnetic density in the iron core is greater than Bn and is close to saturation, that is, the DC current when measuring the DC resistance is equal to 2%-10% of the rated current.If the DC current is too large during the measurement and the measurement time is too long, the resistance will change due to the heating temperature of the winding, which will increase the measurement error.
     
    Pass 
    https://www.cqgoldequipment.com/gdzc-series-transformer-winding-dc-resistance-tester-mirco-ohmmeter.html Learn more about product testing.
  • What is circuit breaker? Types of circuit breakers

    What is a Circuit breaker?
    A circuit breaker (CB) is an automatically operated electric switch designed to protect an electrical circuit from damage caused by an overload or short circuit.Unlike fuses, which must be replaced when they open, a circuit breaker can be reset once the overcurrent condition has been corrected. Pushing the handle to the “OFF” position then back to the “ON” position restores the circuit. If a circuit reopens upon reset to the “ON” position, the circuit should be checked by a qualified electrician.
    Contact breakers vary in size, from small devices that protect someone and household appliances to large switchgear designed to protect high voltage circuits that transmit to the entire city.

    Types of circuit breakers:
    (1)Air Circuit Breakers
    (2)Oil circuit breaker
    (3)Air-Blast Circuit Breakers
    (4)Vacuum Circuit Breaker
    (5)Solid-State Circuit Breaker
  • On-site Fault Analysis of High-voltage Circuit Breaker Characteristic Test

    Through the analysis of the detection principle of the instrument fracture state. The instrument forms a loop through switch, grounding and instrument fracture, and tests the port state of the instrument by detecting the on-off of the entire loop, and also uses this principle to test the opening and closing time of the switch. Generally speaking, we connect the moving/static contact of the high voltage circuit breaker to the fracture test end of the tester, and then short the other contact to ground, the signal of the instrument can form a loop state with the instrument through the switch and the ground.

    In the actual situation, there may be such a situation: we did not exit the remote grounding situation, the contact connected to the instrument was grounded through the remote end, and we short-circuited it to ground at the other contact side. It will cause the dynamic and static contacts of the entire switch to be in a short-circuited state through grounding regardless of the state of the switch, causing the high-voltage circuit breaker dynamic characteristic tester to display that the switch is in the closed state no matter how it is operated.
     
      For this kind of failure, we can solve it in two ways. One is to exit remote grounding through remote grounding control. However, it is worth noting that there is not necessarily only one switch that protects the remote ground. There may be other equipment running. If you exit the remote ground, there will be procedural problems. The second is to change the wiring. This is also the easiest way. We can short-circuit the contact that was supposed to be connected to the ground and then not ground it, but directly connect it to the ground terminal on the instrument, so that the above-mentioned problems will not occur, and the fracture detection of the instrument can also be restored to normal, and the test is also Can go smoothly!
  • What is the importance of using SF6 gas analyzers in gas insulated substations (GIS)?

    A substation consists of many types of equipment such as transformers, circuit breakers, etc, to do the transmission and the distribution of the electric power.The components of the gas insulated substation are closely packed and due to this, the size of the substation has been reduced. The SF6 gas is used as an insulation medium in this substation. The major parts of this substation are contained in a sealed environment, this is achieved by using sulfur hexafluoride gas. So the major components of this substation are enclosed and because of this, the size of this substation is reduced. The high voltage carrying parts of this transformer is situated within a metal enclosure and it is held in a concentric configuration by cast epoxy spacer insulators. The sulfur hexafluoride gas is filled between the insulator and the conductor at a specified amount of pressure.
     
    Therefore, it is very important to use SF6 gas comprehensive analyzer in GIS substation; SF6 gas comprehensive analyzer can detect (dew point) micro water/purity/decomposition products/H2S/SO2 and other gases in SF6 gas.
    The function of SF6 gas comprehensive analyzer:
    1. Quickly save gas
    2. Self-locking connector
    3. Data storage
    4. Curve function
    5. Clear display
    6. Built-in power supply
     

    For product details, please check the official website link below:

    https://www.cqgoldequipment.com/gd-2h-sf6-sf6-synthesized-tester-gas-concentration-sf6-dew-point-sf6-water-content-sf6-purity-tester.html

    Welcome To Inquire!

  • What are the precautions when testing the relay?

    1. For relays with iron shells, the test data should be taken as formal test data after the iron shell is covered.
    2. When the relay is tested for the action value under the setting position, the test should be repeated three times, and the error between each measured value and the setting value shall not exceed the specified range.
    3. When the current or voltage impact test is performed on the relay, the value of the impact current is based on the maximum fault current at the protection installation, and the value of the impact voltage is based on 1.1 times the rated voltage. If negative sequence current or negative sequence voltage is used for impact test, the positive phase sequence can be reversed to negative phase sequence. If there are special requirements for the impact value, it will be clearly stipulated in the relevant chapters.
    4. The change of the test power frequency has a greater impact on the electrical characteristics of some relays. Therefore, when recording the test data of these relays, the power frequency during the test should be indicated.


    The relay tester produced by our company has Single-phase (GDJB-III)/Three-phase (GDJB-PC)/Six-phase (GDJB-1200).
    Welcome to know more details and inquiry!

  • What are the precautions for using the CT/PT tester?

    1)All technical index should keep in work condition before testing with Analyzer.
    2)Please follow associated international standards in a special application.
    3)Forbid high voltage or high current connected to CT/PT Analyzer directly.
    4)All tests need to follow procedure in user manual.
    5)It is forbid to open the box of CT/PT Analyzer. Otherwise, the quality assurance will be invalid.
    6)It is forbid to update or extend the tester without manufacturer authorization.
    7)Please use the original accessories for Analyzer.
    8)It is forbid to cut off test connection before LED indicator light is OFF.
    9)Please connect Analyzer to ground with grounding cable in no laboratory application.
    10)Please confirm that one terminal of sample CT primary connected to ground.
    11)Do not run Analyzer in extreme moist condition.
    12)Please confirm that all terminals connected to Analyzer have no voltage. All voltage outputs are from CT/PT Analyzer.
    13)Please confirm that voltage had been injected to CT secondary winding in CT test. Otherwise, CT/PT Analyzer will be damaged possibly.
    14)Please confirm that voltage had been injected to PT primary winding in PT ratio test. Otherwise, CT/PT Analyzer will be damaged possibly.
    The ratio error and phase angle error test is valid for electromagnetic voltage transformer only. It can not applied in CVT test.

    -Welcome Inquiry-

    https://www.cqgoldequipment.com/gdva-404-ce-certificate-current-transformer-ct-pt-analyzer.html
  • Why is the detection of the secondary circuit so important?

    Although the secondary circuit is not the main body of power transmission and transformation equipment, it only monitors, controls, regulates and protects the primary equipment, but it plays an extremely important role in ensuring the safety of power production and providing qualified power to users. The fault or wrong wiring of the secondary circuit will seriously affect the normal operation of the power system; if the secondary circuit of the transformer differential protection is incorrectly wired, a false trip will occur when the load of the transformer is large or a through-phase short circuit occurs; If the circuit breaker's control circuit and line protection are connected incorrectly, once the system fails, it may cause the circuit breaker to malfunction or refuse to operate, causing equipment damage or even the collapse of the power system.

    Common equipment in the secondary circuit includes comprehensive relay protection, transformers, high-voltage switches, vacuum switches, capacitors, etc.Therefore, our company's secondary circuit test equipment is for these equipment to carry out relay protection test, ct/pt analysis test, ratio difference angle difference test, high-voltage switch contact resistance and dynamic characteristic test and other experimental items.

    Our company's secondary loop testing instrument not only has the superior performance and advanced functions of the large-scale testing instrument, but also has the advantages of small size and flexibility, simple operation and high reliability, and high performance and price ratio.

    Welcome Inquiry!

  • How to Calibrate and Maintain Oil Type Test Transformer

    1. Periodic test contents of high-voltage oil type test transformer include:
     
    1) Oil sample testing-performance indicators such as withstand voltage and impurities are carried out every three years, which can shorten the period of long-term full load or overload operation of the transformer.
     
    2) The high and low voltage insulation resistance is not less than 70% (10MΩ) of the original factory value, the DC resistance of the winding at the same temperature, the difference of the three-phase average value should not be more than 2%, and it is not compared with the result of the last measurement. Should be greater than 2%.
     
    3) The grounding resistance value of the high-voltage test transformer is measured every two years.
     
    4) The cleaning and inspection cycle after power failure is determined according to the surrounding environment and load conditions, usually once half a year to once a year; the main contents include eliminating the defects found in the inspection, cleaning the porcelain sleeve, replacing the broken or aging rubber pad, and checking and tightening the connection point. Lack of oil and replenishing oil, check and replace the silica gel of the respirator, etc.

    2. The daily maintenance methods of high-voltage oil type test transformers are:
     
    1) he grounding of the transformer
    2) The transformer shell should be grounded reliably, and the working neutral wire shall be laid separately from the neutral ground wire, and the working neutral wire shall not be buried in the ground.
    3) The neutral grounding circuit of the high-voltage test transformer should adopt detachable connecting bolts near the transformer.
    4) The grounding of a transformer equipped with a lightning arrester should meet the requirements of the trinity; that is, the neutral point of the transformer, the transformer shell, and the grounding of the arrester should be in one place and grounded together


    Our GDJZ Oil Type Transformer AC DC Hipot Tester is applied in power system for insulation test, withstand voltage of high voltage equipment like power cable, power transformer, switchgear, etc. There are many kinds of output voltage for you choice,
    Welcome Inquiry!  

    https://www.cqgoldequipment.com/gdjz-series-oil-immersed-test-transformer-ac-dc-hipot-tester-for-power-transformer-withstand-voltage-testing.html 
  • How to choose an ultra-low frequency high voltage generator?

    Very Low Freuqency Tester: It is mainly used for non-destructive insulation withstand voltage test of large-capacity test products such as large generators, wires and cables. Use 0.1Hz ultra-low frequency withstand voltage test instead of power frequency withstand voltage test, not only can have the same Equivalent, and the size of the equipment is greatly reduced, and the weight is greatly reduced. Let's take the VLF-Series as an example to illustrate how to select the "Ultra Low Frequency and High Voltage Generator":
    First of all, pay attention to the choice of frequency and voltage level:
    1. The frequency is as low as possible: 0.1Hz, 0.055Hz, 0.02Hz are optional.
    2. Selection of voltage level
    Model 1: GD-VLF/30KV. Rated voltage: 30KV/20mA;
                     Load capacity: 0.1Hz, ≤1.1uF, 0.05Hz, ≤2.2uF, 0.02Hz, ≤5.5uF;
                     Weight: Controller: 4kg, Booster: 25kg.
                     Uses: 10kV cables, generators.
    Model 2: GD-VLF/50KV. Rated voltage: 50KV/30mA;
                      Load capacity: 0.1Hz, ≤1.1uF, 0.05Hz, ≤2.2uF, 0.02Hz, ≤5.5uF;
                      Weight: Controller: 4kg, Booster: 50kg.
                      Purpose: Used for burn-through of cable faults.
    Model 3: GD-VLF/60KV. Rated voltage: 60KV/30mA;
                      Load capacity: 0.1Hz, ≤0.5uF, 0.05Hz, ≤1uF, 0.02Hz, ≤2.5uF.
                      Weight: Controller: 4kg, Booster: 50kg.
                      Uses: 20kV cables, generators.
    Model 4: GD-VLF/80KV. Rated voltage: 80KV/30mA;
                     Load capacity: 0.1Hz, ≤0.5uF, 0.05Hz, ≤1uF, 0.02Hz, ≤2.5uF.
                     Weight: Controller: 4kg, Booster: 75kg.
                     Uses: 35kV cables, generators.
    VLF high voltage Tester-LOGO
  • What are the routine testing items for transformers?

    Before the transformer is officially put into operation, various tests must be carried out on the transformer in accordance with the regulations. The transformer test equipment is used to detect the transformation performance to ensure that the equipment performance is correct and can be operated normally. The routine test items of power transformers are as follows:
    1 Insulating oil test
    2 Measure the DC resistance of the winding and bushing
    3 Check the voltage ratio of all taps
    4 Check the three-phase wiring group of the transformer and the polarity of the lead wire of the single-phase transformer
    5 Measure the insulation resistance of each fastener that is insulated from the iron core (the connecting piece can be detached) and the iron core (with an external ground wire)
    6 Test of non-pure porcelain casing
    7 Inspection and test of on-load voltage regulation switching device
    8 Measure the insulation resistance, absorption ratio or polarization index of the winding and bushing
    9 Measure the tangent value of the dielectric loss angle of the winding and the bushing tanδ
    10 Measure the DC leakage current of the winding and bushing
    11 Transformer winding deformation test
    12 AC withstand voltage test of winding and bushing
    13 Long-term induced voltage test of winding and bushing with partial discharge test
    14 Impulse closing test under rated voltage
    15 Check the phase

  • How often should the transformer be tested?

    The transformer will be inspected once 2 to 3 months after it is put into operation, and once a year thereafter, the inspection contents are mainly:
    (1) Check whether the dry-type transformer pointer thermometer and other instruments and protection devices operate normally;
    (2) Check whether the air duct of the dry-type transformer iron core is blocked by dust, foreign matter, rust or corrosion, etc.;
    (3) Check whether there is dust accumulation, cracks, discoloration, discharge, etc. on the cast-in wingdings and inter-phase connecting wires, and whether the insulation resistance is normal;
    (4) Check whether the winding compression device is loose;
    (5) Check whether the contacts of the tap changer are overheated, discolored, poorly contacted, or corroded.
    (6) Check whether the dry-type transformer cooling device including the motor and fan bearings are in good condition.

  • What is the function of the Oil Type Hipot Tester?

    By generating power frequency high voltage, it can act on the insulating material of the electrical equipment under test to examine whether the equipment under test can work reliably under long-term working voltage and instantaneous over-voltage.
    It is suitable for power systems, industrial and mining enterprises, scientific research departments, etc. to conduct insulation strength and leakage tests under power frequency or DC high voltage for various electrical equipment, electrical components, and insulating materials. It is an essential and important equipment for high voltage testing.
    GDJ Oil type transformer AC DC Hipot tester
    The daily maintenance methods of Oil Type Hipot Tester are:

    ①The grounding of the transformer;
    ②The transformer shell should be grounded reliably, and the working neutral wire should be laid separately from the neutral grounding wire, and the working neutral wire should not be buried in the ground;
    ③The neutral ground loop of the high-voltage test transformer should adopt detachable connecting bolts near the transformer;
    ④The grounding of a transformer equipped with a lightning arrester should meet the requirements of the trinity: that is, the neutral point of the transformer, the transformer shell, and the grounding of the arrester should be in one place and grounded together.

  • The importance and characteristics of relay protection equipment?

    As the first line of defense of the power system security defense system, the relay protection system plays an indispensable role. It is responsible for the function of operating a large working current with a small working current in the control loop of the automation technology.-- "Automatic Switch"

    Product Characteristics

    1. Meet all test requirements on site. According to different voltages/currents, we can provide single-phase/three-phase/six-phase relay protection testers; it can test various traditional relays and protection devices, as well as various modern microcomputer protection tests, especially It is a device for transformer differential protection and automatic switch-on, making the test more convenient and perfect;

    2. Classic WindowsXP operation interface, friendly man-machine interface, easy and quick operation; high-performance embedded industrial control computer and 8.4-inch TFT true color display with 800×600 resolution, which can provide rich and intuitive information, including equipment Current working status and various help information, etc;

    3. The native WindowsXP system comes with a recovery function to avoid system crashes caused by illegal shutdown or misoperation;

    4. Equipped with ultra-thin industrial keyboard and optical mouse, which can complete various operations through keyboard or mouse like ordinary PC;

    5. The main control board adopts DSP+FPGA structure, 16-bit DAC output, and can generate 2000 high-density sine waves per week for the fundamental wave, which greatly improves the quality of the waveform and the accuracy of the tester;

    6. The power amplifier adopts high-fidelity linear power amplifier, which not only ensures the accuracy of small current, but also ensures the stability of large current;

    7. This microcomputer relay protection tester adopts USB interface to directly communicate with PC, without any adapter cables, which is convenient to use;

    8. It can be connected to a laptop computer (optional) for operation. The notebook computer and the industrial computer use the same set of software, no need to relearn the operation method;

    9. Equipped with independent dedicated DC auxiliary voltage source output, the output voltage is 110V (1A), 220V (0.6A). For use in relays or protection devices that require DC power supply;

    10. With software self-calibration function, it avoids the need to open the case and adjust the potentiometer to calibrate the accuracy, thereby greatly improving the stability of the accuracy Cost-effective  .

  • Common methods for AC withstand voltage test of power cross-linked cables

    (1)Very Low Frequency Method

     

    As we know that the cable capacity is large. After the power frequency test, the transformer capacity changes. It is necessary to increase the test power supply with a large capacity to fundamentally ensure that the cable can provide reactive power during operation. However, this method cannot be used in the field. The low frequency is the main test power source. However, the ultra-low frequency method has a relatively poor effect on the insulation defects of the cross-linked polyethylene cable and accessories detected. Therefore, the frequency of the over-frequency method applied to the voltage cable at this stage is relatively high.

     

    (2) Oscillating Voltage Method

     

    When the cable is subjected to DC shock, the resistance and inductance are discharged after a certain voltage, and then the damped vibration voltage is formed. The damped vibration voltage can be used to detect defects in the cable insulation and accessories. This is still very important in the DC withstand voltage test. The effect, but the essence is still mainly manifested in two aspects: on the one hand, the oscillating voltage is weakened, which cannot fundamentally satisfy the cable, on the other hand, the high-frequency voltage will cause varying degrees of damage to the cable.

     

    (3)Resonance withstand voltage method

     

    The resonance withstand voltage method mainly refers to changing the cable and frequency in the experimental circuit to make the circuit as a whole in a resonance state. The resonance withstand voltage method can meet the test requirements of high voltage and large current. In addition, from the point of view of the adjustment method of the resonance withstand voltage method, it can be divided into two types: inductance and frequency modulation. From the use method of the resonance withstand voltage method, it can be divided into two types: series resonance and parallel resonance.

     

    1. Inductive resonance withstand voltage

    After adjusting the power inductance of the reactor and the basic capacity of the cable, resonance will occur at 50HZ, which meets the basic needs of the entire test

     

    2. FM resonance withstand voltage

    When changing the output frequency of the power supply in the test, the fixed inductance in the circuit and the corresponding test piece fundamentally meet the basic requirements of resonance and the basic requirements of the entire test.

     

    3. Series resonance method

       During the test, the current of the transformer must meet the requirements of the test as a whole, but when the voltage does not reach the test voltage, a reactor or a series of test pieces must be selected for the test. When the circuit is in resonance, the test product appears to be a multiple of the corresponding circuit quality factor, and the output voltage of the transformer changes. Before the power supply capacity is satisfied, the effective power in the circuit will be lost.

     

    4. Parallel resonance method

    In the test, when the voltage of the transformer meets the test requirements and the current does not meet the requirements, the reactor and the test product are connected in parallel to meet the circuit parameters required for resonance in the test to promote the active development of the test. At the same time, the parallel resonance method and reactor are selected. The basic inductive current compensates the capacitive current of the test product.

  • What are the precautions for using the transformer turns ratio tester?

    1.Use Proper Power Cord

    Only use the power wire supplied by the product or meet the specification of this produce.

    2.Connect and Disconnect Correctly

    When the test wire is connected to the live terminal, please do not connect or disconnect the test wire.

    3.Grounding

    The product is grounded through the power wire; besides, the ground pole of the shell must be grounded. To prevent electric shock, the grounding conductor must be connected to the ground.
    Make sure the product has been grounded correctly before connecting with the input/output port.

    4.Pay Attention to the Ratings of All Terminals

    To prevent the fire hazard or electric shock, please be care of all ratings and labels/marks of this product. Before connecting, please read the instruction manual to acquire information about the ratings.

    5.Do Not Operate without Covers

    Do not operate this product when covers or panels removed.

    6.Use Proper Fuse

    Only use the fuse with type and rating specified for the product.

    7.Avoid Touching Bare Circuit and Charged Metal

    Do not touch the bare connection points and parts of energized equipment.

    8.Do Not Operate with Suspicious Failures

    If you encounter operating failure, do not continue. Please contact with our maintenance staff.

    !Do Not Operate in Wet/Damp Conditions. 

    !Do Not Operate in Explosive Atmospheres.

    !Ensure Product Surfaces Clean and Dry.

    0.1Variable Ratio Group Tester Transformer Ratio Automatic Tester For Power System Laboratory Testing 

  • What is the purpose of DC resistance testing for transformers?

    The DC resistance of the transformer refers to the DC resistance value of each phase winding. The purpose of measuring the DC resistance is to check whether there is an inter-turn short circuit inside the three-phase winding;
    Because if there is a short-circuit between phases in the transformer, the short-circuit current value is very large, it is easy to burn the transformer, the phenomenon of the fault is also obvious, and the appearance is easy to judge; however, if a short-circuit occurs between the winding turns of one of the phases, the short-circuit current If the value is very small, the automatic transformer protection will trip. However, it is difficult to see whether the transformer itself is faulty from the appearance of the transformer. By measuring the DC resistance of each phase and comparing the resistance values of the three phases, it is easy to determine whether an inter-turn short-circuit occurs inside: the resistance value is large, and the possibility of inter-turn short-circuit failure is great; if it is basically similar, this can be ruled out. The possibility of a failure.

    In summary, the purpose of measuring the DC resistance is to determine whether the transformer has an inter-turn short circuit or whether the line falls off, so as to facilitate troubleshooting.

    Panel display of GDZC-Series DC resistance tester
    GDZC-series transformer winding resistance tester Intelligent loop DC resistance power analyzer

     
     
  • What service can our company provide you?

    Pre-sale Service:
    1. The professional sales team will reply to the inquiry in real time;
    2. Customize suitable solutions according to the needs of different customers;
    3. Provide product technical parameters/operation manuals and evaluation reports, etc.;
    4. During the global 
    COVID-19, video factory inspections are supported.
     
    After-sale Service:
    1.From the date of purchase within one year instrument, is a product quality problem free repair replacement, lifetime supply of maintenance and technical services.
    2.Technical Support
    (1)Our technical team supports our customers at all time with our long experience, expert advice and the unlimited spirit and always be for providing the best customer service.
    (3)Training how to install the machine,you can arrange your engineer to our company to get free training.
    (4)If necessary, we can also arrange our engineer to your company for training and commissioning at your cost.
    3.The instrument has found anomalies or malfunctions please contact us to arrange the most convenient treatment options.

  • Why do transformers need tan delta and power factor tester?

    Its function is to check the overall moisture/aging of the transformer, and to find dust and serious local defects on the windings. The measurement results of the dielectric loss factor are often affected by surface leakage and external conditions. Measures should be taken to reduce and eliminate this effect (for example, using the inter-frequency method/frequency conversion method to resist interference).
    The measured dielectric loss factor value refers to the reference standard of the measurement together with the casing. However, in order to improve the accuracy of the measurement and further detect the sensitivity of the defect, if necessary, a decomposition test can be carried out to determine the location of the defect.
     

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