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What device detects partial discharge?
2025-07-04What equipment can detect partial discharge?Let's analyze Partial Discharge Testers – instruments specifically designed to capture, measure, and analyze partial discharge phenomena occurring within electrical equipment. Based on detection principles and application scenarios, the main types are:1.Pulse Current (IEC 60270):Measures: Current pulses in ground connection.Pros: Most accurate quantification (pC).Cons: Needs direct connection, often offline, sensitive to noise.Use: Lab/factory tests, critical offline diagnostics (transformers, cables).2.Ultra-High Frequency (UHF):Measures: Radio waves (300MHz-3GHz) from PD.Pros: Non-contact, good noise immunity, online capable.Cons: Hard to calibrate (pC), complex signal paths.Use: Online monitoring (GIS/GIL), transformers, switchgear.3.Ultrasonic (Acoustic):Measures: Sound waves (20kHz-300kHz) from PD.Pros: Pinpoints location, immune to electrical noise, online capable.Cons: Hard to quantify (pC), signal weakens through material.Use: Loc
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What is a PD inspection?
2025-07-03The PD tester under Wuhan UHV can help many power workers conduct various power tests more conveniently.PD Inspection (Partial Discharge Inspection)Definition:A critical non-destructive testing and diagnostic technique for assessing the insulation systems of electrical equipment (especially high-voltage assets). It detects, measures, and analyzes partial discharge phenomena within insulation structures.1. Purpose of PD InspectionEvaluate insulation integrity.Provide early fault detection.Ensure manufacturing/installation quality.Enable predictive maintenance (avoid unplanned downtime).Diagnose root causes post-failure.2.How to conduct PD examination? (Main detection methods)PD can produce various physical and chemical effects, therefore there are multiple detection methods:Electrical measurement method:Pulse current method: the most classic and standardized method. By detecting the pulse current signal generated by PD collected by coupling capacitors or high-frequency current transform
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What is the difference between primary and secondary current injection test set?
2025-07-03The Primary Injection Test Set under Wuhan UHV can help many power workers conduct various power tests more conveniently.Primary Current Injection Test Set1.Injection Point: Test current is injected directly into the primary circuit (e.g., onto the busbar, cable lug, or the primary terminals of the Current Transformer (CT)).2.Current Magnitude: Generates very high currents (hundreds or thousands of Amperes) to simulate real-world fault conditions flowing through the primary conductors and the CT.3.What it Tests/Verifies:The entire current path: Primary conductors, CT primary winding, CT core, CT secondary winding, secondary wiring (cables, terminals), connections, and finally the protective relay itself.CT Performance: Accuracy, ratio, polarity, saturation characteristics under high fault current.Wiring Integrity: Correctness of the entire secondary circuit from CT terminals to relay inputs (phasing, grounding, shorts, opens).Overall System Performance: Verifies that the entire protect
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What is the difference between primary and secondary injection kit?
2025-07-02The Primary Current Injection Test Kit under Wuhan UHV can help many power workers conduct various power tests more conveniently. The difference between primary and secondary injection kits lies in where they inject test current and what part of the protection system they test. Here's a breakdown:1. Secondary Injection Kit:Target: The relay itself (specifically its input terminals).Injection Point: Directly into the secondary terminals of the Current Transformers (CTs) and Voltage Transformers (VTs) - which is where the relay normally connects.Current Level: Low current (typically milliamps to a few amps). Simulates the secondary signals the relay sees from the CTs/VTs.Purpose:Verify the relay's internal functionality: Settings, logic, timing, pickup/dropout, characteristic curves (e.g., IDMT), output contacts, communications.Test the relay in isolation from the actual primary circuit and instrument transformers.Commissioning, routine maintenance, troubleshooting relay-specific
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How often should protection relays be tested?
2025-07-02The Relay Protection Tester under Wuhan UHV can help many power workers conduct various power tests more conveniently.Protection relays act as the "safety guardians" of power systems. While there is no absolute uniform standard for testing frequency—as it depends on multiple factors—regular testing is mandatory to ensure reliable operation during critical events and prevent catastrophic failures.Key Factors Influencing Testing IntervalsManufacturer RecommendationsThe primary reference. Relay manuals or maintenance guides typically specify recommended testing intervals. Always prioritize these guidelines.Equipment CriticalityCritical assets (e.g., generators, main transformers, essential busbars, high-capacity feeders):Failure may cause widespread outages, major equipment damage, or safety hazards.→ Highest frequency: Annual comprehensive functional and calibration testing at minimum.Less critical assets (e.g., general distribution feeders, motors):→ Lower frequency: Testing every
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How to check motor DC or AC?
2025-06-30The AC/DC Motor Test Bench under Wuhan UHV can help many power workers conduct various power tests more conveniently.1.Check the Nameplate (Most Reliable):Locate the nameplate on the motor housing.Look for voltage markings: "DC" or "V DC" (e.g., 12V DC) indicates a DC motor. "AC" or "V AC" (e.g., 220V AC) or a frequency rating (50Hz/60Hz) indicates an AC motor.Check the model number: "DC" or "BLDC" usually means DC; "AC" usually means AC. 2.Inspect Physical Structure & Wiring:Commutator and Brushes visible (open the rear cover to see segmented copper rings and spring-loaded carbon blocks): Very likely a Brushed DC Motor.No Commutator/Brushes: Could be an AC motor or a Brushless DC (BLDC) motor.Number of Power Wires:Only 2 wires: Could be a DC motor or a simple single-phase AC motor (needs further testing).3 main wires (labeled U/V/W): Typically an AC Three-Phase Motor.3 wires (may include capacitor leads): Typically an AC Single-Phase Motor. 3.Measure Resistance (Multimeter):Three-Phas
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What is an electrical test bench?
2025-06-30The Transformer Test Bench under Wuhan UHV can help many power workers conduct various power tests more conveniently.An Electrical Test Bench is a comprehensive platform used for testing, verifying, diagnosing, and evaluating the performance of various electrical equipment, components, systems, or circuits. Its scope is broader than a Motor Test Bench, encompassing not just rotating machines (motors/generators), but also transformers, switchgear, circuit breakers, relays, contactors, controllers, power supplies, wiring harnesses, cables, electronic circuit boards, and even entire electrical systems. Core Functions & Test Items1.Performance Characterization:Input/Output Characteristics (voltage regulation, load regulation, efficiency).Start-up/Shut-down Characteristics.Steady-State and Dynamic Response (e.g., response to load/input steps).Power Factor Correction (PFC) Performance.Output Ripple & Noise.2.Safety & Compliance Testing:Insulation Resistance Test: Verifies insulation integrit
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What is the standard for motor testing?
2025-06-27The Motor Test System under Wuhan UHV can help many power workers conduct various power tests more conveniently.I. Core International StandardsIEC 60034 SeriesIEC 60034-1: General performance & safety requirements (temperature rise/voltage withstand baseline)IEC 60034-2-1: Precision efficiency testing (basis for IE classification)IEC 60034-30-1: Defines global IE1-IE5 efficiency classesII. Regional Mandatory StandardsChina:GB 18613 (Mandatory efficiency, equivalent to IE3/IE4)GB/T 755 (Aligns with IEC 60034-1)North America:NEMA MG-1 (Core industrial motor specification)IEEE 112 (Primary efficiency test method)European Union:EN 60000 Series (Full adoption of IEC standards)EU Regulation 2019/1781 (Mandates IE3/IE4 efficiency)III. Key Test Item StandardsEfficiency: IEC 60034-2-1 or IEEE 112Temperature Rise: IEC 60034-1 Section 6 (limits by insulation class)Voltage Withstand: IEC 60034-1 Section 8.3 (2Un + 1000V/1 minute)Vibration: IEC 60034-14 (Class A/N levels)Noise: IEC 60034-9 (graded
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What does a CT meter do?
2025-06-27The CT Tester under Wuhan UHV can help many power workers conduct various power tests more conveniently.I. Core Testing Functions1.Turns Ratio TestingPrecisely measures the actual primary-to-secondary current ratio of CTs.Verifies compliance with nameplate ratings (e.g., 1000A/1A).Criticality: Incorrect ratios cause metering errors or protection maloperation.2.Polarity VerificationDetermines the relative polarity (dot convention) of primary and secondary windings.Criticality: Polarity errors may lead to meter reversal, differential protection failure, or false tripping.3.Excitation Characteristic (V-I Curve) TestingPlots the excitation current vs. voltage curve (I-V curve) of secondary windings.Derives key parameters:Knee-Point Voltage/Current: Identifies CT core saturation threshold.Accuracy Limit Factor (ALF): Evaluates protection-class CT accuracy under fault currents.Composite Error: Core performance metric for protection CTs.Criticality: Determines CT reliability during fault cond
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Which instrument should be used to perform a dielectric watt loss test?
2025-06-26The core instrument used for dielectric loss testing (loss tangent tanδ measurement) is a Dielectric Loss Test Set, also known as a Tan Delta Tester or Schering Bridge. Based on technical principles and automation levels, the main types are:1. Traditional Schering BridgePrinciple: Classic balanced bridge method requiring manual adjustment of resistive/capacitive arms to achieve balance for calculating tanδ and capacitance.Characteristics:High accuracy (historically the laboratory standard).Complex operation, demanding skilled personnel.Slow testing speed.Requires external HV source (e.g., test transformer) and reference capacitor.Application: Laboratory precision measurements or calibration reference. Rarely used for field preventative testing today.2. Digital Automatic Dielectric Loss TestersPrinciple: Uses digital measurement techniques (e.g., digital sampling, vector analysis) to automatically measure current magnitude/phase difference under applied voltage. Directly calculates and
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What is the purpose of transformer turns ratio test?
2025-06-26Transformer Turns Ratio (TTR) testing (also known as ratio testing or turns ratio testing) is a core and fundamental test in transformer manufacturing, installation, and maintenance. Its main purposes include the following aspects:1.Verify Design Intent and Manufacturing Correctness:This is the most fundamental purpose. The turns ratio is one of the most critical design parameters of a transformer, directly determining the proportional relationship between input and output voltage (neglecting losses and excitation current).The test ensures that the windings were wound with the exact number of turns specified by the design, confirming the transformer can provide the intended voltage transformation function.2.Detect Winding Defects:Interturn Short Circuits: This is one of the most important fault detection purposes. Even a short circuit involving only a few turns will significantly alter the effective number of turns in that winding, causing the turns ratio for that phase to deviate from
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What is a DC winding resistance test?
2025-06-25A DC Winding Resistance Test is a fundamental electrical measurement used to determine the ohmic resistance of windings in devices like transformers, motors, generators, and reactors. Performed with direct current (DC), it eliminates inductive effects, providing precise resistance values for quality control, diagnostics, and performance validation. Purpose1.Baseline Data: Establish reference resistance for future comparisons.2.Fault Detection: Identify issues like loose connections, broken conductors, or uneven winding turns.3.Loss Calculation: Compute copper (I²R) losses for efficiency analysis.4.Temperature Validation: Verify winding temperature rise during heat runs. Test EquipmentPrimary Tools:Micro-ohmmeter (4-wire Kelvin method, accuracy ±0.1%).DC resistance bridge (Wheatstone/Kelvin bridge for high precision).Alternatives:Voltmeter-ammeter method (less accurate, requires stable current source).Accessories:Temperature sensor (infrared gun or RTD), current clamps, heavy-duty leads
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What is variable frequency AC series resonant test system?
2025-06-25A Variable-Frequency AC Series Resonant Test System is an insulation performance testing device that utilizes the principle of series resonance and variable-frequency technology to achieve efficient high-voltage output. It is specifically designed for on-site AC withstand voltage testing of large electrical equipment (such as power cables, transformers, GIS, etc.). Its core principle is to adjust the power supply frequency to achieve resonance in the circuit, thereby generating the required high voltage using a relatively small-capacity power supply.I. System Components1.Variable-Frequency Power SupplyThe core control unit, outputs a sine wave with adjustable frequency (typically 30-300 Hz).Automatically scans for the resonant point and adjusts the frequency in real-time to maintain resonance.2.Excitation TransformerProvides voltage step-up and isolation, boosting the output voltage of the variable-frequency power supply to the initial voltage required for resonance (designed with smal
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What is the difference between AC and DC hipot test?
2025-06-24The DC hipot tester under Wuhan UHV can help many power workers conduct various power tests more conveniently.1.Applied Voltage:AC Test: Applies power-frequency (50/60Hz) sinusoidal AC voltage.DC Test: Applies constant or slowly rising DC voltage.2.Simulates Real Operation:AC Test: Most accurately simulates the AC voltage stress equipment experiences during actual operation. It's the gold standard for AC equipment insulation strength assessment.DC Test: Primarily simulates stress for DC equipment or serves as a supplementary test for AC equipment.3.Primary Applications:AC Test: Widely used for most AC power equipment (transformers, GIS, circuit breakers, instrument transformers, generator stators).DC Test: Particularly suited for long power cables and generator rotor windings; also used for leakage current measurement on some HV equipment (e.g., bushings, arresters).4.Defect Detection Focus:AC Test: Highly sensitive to overall insulation degradation, partial discharges (caused by v
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What is the difference between DC hipot and Megger?
2025-06-24The DC hipot test Kit under Wuhan UHV can help many power workers conduct various power tests more conveniently.1.DC Hipot TestPurpose: Verifies dielectric strength – the insulation’s ability to withstand high voltage without breaking down.Method: Applies a destructively high DC voltage (e.g., 2× to 10× operating voltage) to the insulation.Measurement: Monitors leakage current (µA/mA).Outcome: Pass/Fail (fails if current exceeds threshold or breakdown occurs).Risk: Potentially damages weak insulation. Critical safety step: Must discharge capacitive loads post-test.Use Cases:Safety certification (UL/IEC compliance).Production line quality checks.Detecting critical flaws (cracks, voids, thin spots).2.Megger TestPurpose: Measures insulation resistance – quantitative health of the insulation.Method: Applies a safe, low-to-medium DC voltage (e.g., 500V, 1000V, 2500V).Measurement: Reads resistance (MΩ/GΩ). Higher values = better insulation.Outcome: Numeric value (e.g., "200 MΩ"), used for tr
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AC voltage withstand test plan
2025-06-23AC voltage withstand test plan? Wuhan UHV specializes in producing AC withstand voltage testing equipment, with a wide range of product options. When looking for AC withstand voltage testing equipment, choose Wuhan UHV. In electrical engineering, equipment insulation testing is an important means to ensure the normal operation of electrical equipment in the device and to promptly detect potential insulation performance cracking faults caused by collisions, vibrations, and other factors during manufacturing and transportation. Through electrical testing, the insulation condition of electrical equipment can be understood, and problems can be promptly solved or replaced to ensure the normal operation of the electrical equipment in the device.test methodInsulation resistance, absorption ratio, and polarization index test(1) The significance and role of the experimentMeasuring the insulation resistance of electrical equipment can sensitively reflect the insulation condition, effectively de
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AC voltage withstand test equipment
2025-06-23AC voltage withstand test equipment? Wuhan UHV specializes in producing AC withstand voltage testing equipment, with a wide range of product options. When looking for AC withstand voltage testing equipment, choose Wuhan UHV. The AC withstand voltage test of various large power transformers, power cables, steam turbines, hydro generators, and other capacitive equipment must be strictly conducted regularly in accordance with the test regulations. Under power frequency conditions, due to the large capacitance of the test object or high requirements for the test voltage, there are also high requirements for the power capacity of the test device. In order to ensure the safe and reliable operation of the cable, relevant international standards have made clear provisions for various tests of the cable. The main test items include measuring insulation resistance, DC withstand voltage, and leakage current. The measurement of insulation resistance is mainly used to check whether the cabl
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What is the voltage for VLF cable test?
2025-06-19The VLF cable tester under Wuhan UHV can help many power workers conduct various power tests more conveniently.Core Voltage Parameters1.Base Standard:VLF testing applies 0.1 Hz AC high voltage at 2 to 3 times the cable’s rated voltage (U₀).Examples:10 kV rated cable → Test voltage: 22–28 kV (typically 28 kV).35 kV rated cable → Test voltage: 70–105 kV (commonly 52–65 kV, subject to standards).2.Calculation Basis:Formula: Test voltage = (2.0 ~ 3.0) × Rated Voltage (U₀).International Standards:IEEE 400.2: Mandates 2U₀ for 15 minutes or 3U₀ for 30 minutes.IEC 60502-2: Requires 3U₀ for new cables; diagnostic tests on aged cables may use 2U₀.3.Safety Limits:Never exceed 3U₀: Higher voltages risk damaging healthy insulation.XLPE Cable Protection: 0.1 Hz polarity reversal prevents space charge buildup, ensuring test safety.Special Scenario AdjustmentsAged/Damaged Cables: Voltage may be reduced to 1.6U₀ (supported by tanδ diagnostics).Post-Repair Verification: 2U₀ for 15 minutes (per IEEE 400.
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What is the difference between IR test and VLF test?
2025-06-19The VLF hipot tester under Wuhan UHV can help many power workers conduct various power tests more conveniently.1. Fundamental PrinciplesIR Testing: Applies low-voltage DC (typically 500V–10kV) to measure leakage current and calculate insulation resistance (in MΩ or GΩ). It is a static resistance measurement, analogous to using a multimeter.VLF Testing: Applies 0.1 Hz very low-frequency AC high voltage (2–3 times rated cable voltage, e.g., 28kV for a 10kV cable) to simulate power-frequency voltage stress, performing a dynamic withstand test + diagnostics.2. Core ObjectivesIR Testing:Detects bulk insulation degradation (e.g., moisture ingress, contamination, major damage).Provides the Polarization Index (PI) to assess moisture absorption trends.VLF Testing:Identifies latent defects (water trees, voids, interfacial aging).Verifies cable withstand strength (whether breakdown occurs under high voltage).Combines tan delta (tanδ) and partial discharge (PD) measurements to locate defects.3.Saf
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Purpose of AC withstand voltage test
2025-06-18What is the purpose of the communication withstand voltage test? Wuhan UHV specializes in producing AC withstand voltage testerswith a wide range of product options. When looking for an AC withstand voltage tester, choose Wuhan UHV.1、 Purpose of communication withstand voltage testThe AC withstand voltage test of a transformer is a test in which a sine frequency AC test voltage exceeding a certain multiple of the rated voltage is applied to the winding and bushing of the tested transformer for a duration of 1 minute. The purpose is to use a test voltage that is a certain multiple higher than the rated voltage instead of atmospheric overvoltage and internal overvoltage to assess the insulation performance of transformers. It is the most effective way to evaluate the insulation strength of transformers and an important experimental project to ensure the safe operation of transformers and avoid insulation accidents. Conducting AC withstand voltage tests can discover moisture and concentra
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