Wuhan GDZX Power Equipment Co., Ltd

Why Do We Conduct Power Frequency Withstand Voltage Tests?

In the power industry, insulation performance is the key to ensuring the safe and reliable operation of electrical equipment. To verify insulation levels, the Power Frequency Withstand Voltage Test has become an essential inspection during manufacturing, installation, and operation stages. What is the Power Frequency Withstand Voltage Test? The Power Frequency Withstand Voltage Test, also known as the AC Withstand Test, applies a power-frequency voltage higher than the rated operating voltage to electrical equipment for a specified duration. Its purpose is to check whether the insulation can withstand the applied voltage without breakdown or flashover. This is one of the most fundamental and critical insulation tests. Why is the Test Necessary? 1. Verify Insulation StrengthEquipment such as cables, transformers, switchgear, and instrument transformers must operate under long-term power-frequency voltage. This test ensures their insulation strength meets requirements and can withstand real operating conditions. 2. Detect Potential DefectsInsulation may deteriorate due to factors such as moisture, aging, surface damage, or manufacturing flaws. By applying a higher voltage, this test helps uncover hidden issues early, allowing timely maintenance and repair. 3. Comply with Industry StandardsInternational and national standards (IEC, IEEE, GB, etc.) mandate power frequency withstand voltage testing as a critical step for factory inspection, acceptance testing, and preventive maintenance. 4. Ensure Grid and Personnel SafetyInsufficient insulation in service may lead to breakdown, short circuits, outages, or even personal injury. This test significantly reduces such risks, ensuring both system stability and operator safety. Conclusion The Power Frequency Withstand Voltage Test is not only a “quality checkpoint” in the manufacturing and operation of electrical equipment, but also an essential safeguard for the safe and stable operation of the power grid. By verifying insulation performance, detecting potential defects, and meeting industry standards, it plays a vital role in improving the safety and reliability of power systems. Power safety is never a small matter — it starts with reliable withstand voltage testing to safeguard every kilowatt-hour of electricity.

ZXVLF Series Very Low Frequency (VLF) AC Hipot Tester

The ZXVLF series Very Low Frequency (VLF) high-voltage generator is a specialized device for conducting withstand voltage tests and insulation diagnostics on medium- and high-voltage power cables, rotating electrical machines (such as generators and large motors), and other capacitive electrical equipment (such as power capacitors and cable accessories). By generating a 0.1Hz ultra-low frequency sinusoidal high voltage, it provides an equivalent replacement for power frequency (50Hz/60Hz) withstand voltage testing. This eliminates the challenges associated with testing large-capacity specimens (such as long cables) at power frequencies, which typically require bulky, cumbersome equipment that is difficult to transport and handle on-site.  It is widely used for cables, generators, motors, transformers, and switchgear, fully meeting IEC, IEEE, and national power industry standards.       Key Features High Intelligence: Digital frequency conversion technology with microcomputer control enables fully automatic boosting, lowering, and measurement. Easy Operation: Simple wiring, 7-inch LCD touch screen, and user-friendly interface. Comprehensive Protection: Over-voltage and over-current protection on both HV and LV sides, fast response (≤10ms), ensuring safety. Safe & Reliable: Controller and HV generator are connected via low-voltage photoelectric isolation for maximum safety. Stable Output: Equipped with HV/LV closed-loop negative feedback circuit to eliminate capacitance rising effect. Accurate Sampling: Voltage and current data are directly sampled on the HV side for true and precise results. Well Equipped: 7-inch capacitive touch screen, LCD display, automatic storage, and printing functions. Wide Test Range: Multiple frequency options (0.1Hz, 0.05Hz, 0.02Hz) to cover different test objects. Portable: Compact and lightweight, convenient for field testing. Multi-language Display: Supports Chinese-English switch, other languages customizable.

What is Contact Resistance?

When two conductors touch, you’d expect electricity to flow freely — but in reality, it doesn’t.On a microscopic level, metal surfaces are rough, so current only passes through a few tiny spots. This creates contact resistance. Why it matters:Too much contact resistance in switches, breakers, or busbar joints can cause: Overheating  Power losses  Damaged contacts Equipment failure What causes it? Constriction effect – Current squeezed through tiny contact spots Surface films – Oxides, moisture, or dirt blocking current Material factors – Some metals (like silver, gold) resist oxidation better than copper How do we test it? The standard way is the DC voltage drop method: Apply high current (100A–600A) Measure the tiny voltage drop Use Ohm’s law R=U/IR = U / IR=U/I to calculate resistance In short:Contact resistance may be small, but it can cause big problems. That’s why regular testing is essential to keep electrical equipment safe and reliable. Do you monitor contact resistance in your projects?

What is a Circuit Breaker Tester and Why It Matters for Power System Safety

Introduction:Circuit breakers are the guardians of our power systems. When a fault occurs, such as a short circuit or overload, they act instantly to disconnect the faulty part of the circuit, preventing accidents from spreading. Ensuring that circuit breakers operate reliably is critical — and that’s where circuit breaker testers come in. What is a Circuit Breaker Tester? A Circuit Breaker Tester is a specialized electrical testing device used to detect, verify, and evaluate the performance of high- and low-voltage circuit breakers. It helps power professionals ensure that circuit breakers are ready to perform when the grid demands. Main Functions 1. Operating Time TestMeasures the closing and opening time, as well as three-phase asynchronism, to determine whether the circuit breaker operates accurately and responsively. 2. Mechanical Characteristic TestEvaluates parameters such as opening/closing speed, stroke, over-travel, and rebound amplitude to assess the mechanical performance of the breaker. 3. Dynamic Characteristic TestAnalyzes dynamic current and voltage waveforms to study the breaker’s behavior during operation. 4. Main Circuit Resistance TestMeasures the contact resistance of the breaker to assess its conductivity and contact condition. 5. Minimum Break Time and Reclosing TestChecks the breaker’s ability to open and close repeatedly within a short time, ensuring it meets the fast switching requirements of the power grid. Application Scenarios Power plants and substations Power maintenance departments High-voltage switchgear manufacturers Electrical research institutes Conclusion:In short, a circuit breaker tester is like a “doctor” for circuit breakers. By conducting a series of electrical and mechanical tests, it ensures that breakers operate safely, quickly, and reliably — keeping the power grid secure at all times.

What is a Relay Protection Tester?

Core Definition A Relay Protection Tester (also known as an Automated Test Set) is a specialized electronic device designed to test and verify the performance and reliability of protective relays in power systems. Functions & Capabilities Fault Simulation: Accurately generates fault signals such as overcurrent, over/under voltage, distance protection, differential protection, and frequency deviation. Logic Verification: Ensures the relay can correctly and promptly issue trip commands to circuit breakers when abnormal conditions are detected. Setting Verification: Confirms that the relay operates precisely at the configured set points (current, voltage, time) as required by the grid standards. Automated Testing: With dedicated software, the tester can automatically run complex test sequences and generate comprehensive test reports. Application Value Relay protection testers are essential for ensuring the safe and stable operation of power systems. They are widely used for: Routine maintenance and inspection of power equipment Acceptance testing of new installations before commissioning Post-fault analysis to verify relay operation and protection logic The importance of relay testing lies in the fact that, during a short circuit or ground fault, the reliability and speed of relay operation (often within milliseconds) directly determine whether: Equipment is protected from severe damage The power grid remains stable or suffers a large-scale blackout Safety incidents can be prevented Thus, relay protection testers are an indispensable tool in power plants, substations, and transmission networks. GDZX Advantages GDZX offers a wide range of relay protection testers, from standard models to advanced automated solutions, meeting diverse testing requirements across the power industry.Feel free to contact us anytime for detailed solutions and quotations.

GDZX-September Procurement Festival · Limited-Time Promotion！！！

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What is Working Principle of Current Transformers?

A Current Transformer (CT) is a critical metering and protection device widely used in power systems. Its primary function is to convert high-voltage, large currents into proportional low-voltage, small currents for measuring instruments and protective relays, ensuring accurate energy metering and safe system operation. In power plants, substations, and user-side high-voltage metering systems, CT accuracy directly affects stakeholders across generation, transmission, and consumption. Therefore, CTs must be verified in accordance with IEC 61869 Instrument Transformers series standards (e.g., IEC 61869-2 for current transformers, IEC 61869-3 for voltage transformers) and related IEC 60044 standards. Working Principle The operating principle of a CT is based on electromagnetic induction. It consists of a primary winding, secondary winding, and magnetic core: The primary winding is connected in series with the high-voltage circuit and carries a large current. The secondary winding delivers a proportionally reduced current (typically 5A or 1A) for metering and protection devices. Through the transformation ratio, the CT accurately reflects the magnitude of the primary current. To ensure measurement accuracy, CT errors must be strictly controlled within specified IEC accuracy classes (e.g., Class 0.2S, 0.5S). Next-Generation On-Site Calibration Technology Traditional CT verification methods often require bulky auxiliary equipment such as reference transformers, current boosters, and load boxes—leading to complex wiring, heavy workloads, and low efficiency. Our newly developed Next-Generation CT Field Calibrator addresses these challenges through advanced innovations: Recursive Error Measurement & Impedance-Admittance Algorithms for high-precision deduction. Near-Power-Frequency Excitation to suppress electromagnetic interference. Built-in IEC Class 0.05 reference CT/VT, eliminating the need for external reference devices. With these technologies, on-site verification becomes simple, fast, and reliable: Ultra-Wide Measurement Range: 5A/5A to 31,500A/5A. Instant Compliance Verdict: 1-second “Pass/Fail” judgment. Smart Diagnostics: Automatic detection of wiring, ratio, and polarity errors. Efficient Data Management: Stores up to 1,000 test results with direct report printing. This breakthrough reduces the workload dramatically, enabling a single technician to perform verification tasks that previously required multiple staff, while significantly improving efficiency and accuracy.

ZXHQ-A+ Full Automatic 3000V Transformer Comprehensive Tester 500KV level 1A Volt-Ampere Characteristic Test

The ZXHQ-A+ Fully Automatic Transformer Comprehensive Tester requires only simple digital settings: set the rated parameters of the transformer. The instrument automatically records all data throughout the process and calculates and displays parameters such as the transformation ratio polarity and voltage-current characteristic curves, eliminating the need for tedious tasks such as changing wires, manual voltage adjustment, manual data recording, data organization, and curve plotting. Using simple operation and wiring methods to measure transformers significantly reduces work intensity and improves efficiency, making it convenient to conduct transformer measurements on-site; quick, simple, and convenient. Performance Features  : 1. Voltage-Current Characteristic Testing: The maximum output voltage of the single unit reaches up to 2500V, making it suitable for voltage-current characteristic testing of 500kV-class 1A current transformers. Turns Ratio Testing: The maximum current output reaches up to 600A. The device's power output provides true voltage and current values, with waveforms being standard sine waves at a frequency of 50Hz; it can effectively simulate the actual state of the transformer, complying with national maintenance regulations. The voltage regulation resolution can be as low as 0.13V. 2. Can test CT/PT for: “volt-ampere characteristics,” “5%, 10%, and 15% error curves,” “turns ratio and polarity,” “phase angle error and ratio error,” “secondary direct resistance,” “secondary load,” “secondary circuit,” “secondary withstand voltage,” and demagnetization function. 3. Testing complies with IEC 61869-3:2011, IEC 61869-2:2011, and other transformer standards, and automatically selects the appropriate standard for testing based on the transformer type and grade. 4. The 7-inch color touchscreen includes a Chinese input method, allowing for the input of Chinese codes. 5. The interface is user-friendly and aesthetically pleasing, featuring a fully Chinese graphical interface. The panel includes a built-in printer, enabling the printing of curve diagrams and test data at any time. 6. Equipped with a large-capacity storage device, it can store 4,000 sets of test data, with data retained even in the event of a power outage. 7. After testing, data can be saved to a USB drive and analyzed using software on a computer, with the ability to generate a Word report.   8. Features online functionality, allowing the instrument to be controlled via a computer for testing. 9. Automatic calculation of inflection points; comprehensive data query, browsing, printing, and deletion functions; built-in date/time functionality. 10. All-in-one design, lightweight at only 26 kg, easy to carry, and suitable for mobile testing.