VLF Hipot Tester
A Prominent Manufacturer of VLF Hipot Tester
Our company has specialized in the production and manufacturing of Series Resonant Tester for 20 years, with a modern intelligent factory covering an area of over 10000 square meters, staffed by 51 professional technicians, and hold CE certification. 35 patents, 10+ software copyrights，Currently, we have over 150 stable distributors worldwide and established more than 10 service offices overseas.
VLF Hipot Tester (Very Low Frequency High Potential Tester) is a specialized piece of electrical test equipment used to assess the integrity of the insulation in high-voltage components, primarily cables, but also switchgear, transformers, and motors.
The core function is to apply a high AC voltage at a very low frequency (typically 0.1 Hz or 0.01 Hz) to the insulation of the test object. This high voltage stresses the insulation, allowing technicians to identify weaknesses, flaws, or impending failures without causing undue stress to the insulation system itself.
Our Advantages
- Professional Consultation – Respond technical enquiries within one hours;
- Detailed Documentation – Dispatch requested technical materials within one hour;
- Competitive Quotation – Provide a reasonable quotation within two hours.
- Certificated By CE, lSO9001,SGS, BV,TUV.
- Trust And RecognitionFrom 180 Countries And Regions
- High-Level Professional Factory With Over 45.000 m
- Product demonstration videos
- Strict contract requirements
- Timely production progress updates synchronization
- On-time delivery
- 12-month warranty
- Overseas training support
- Regular follow-ups by professionals
- Extended warranty (optional)
- Factory testing available
- CE certification
- 35 patents
- 10+ software copyrights
- Customization available
- Professional after-sales Team
- Product Innovation
- Quality Control
- Authorized calibration (optional)
- Authorized as a National-Level “High-Tech Enterprise”
- Wuhan Technology Innovation "Gazelle" Enterprise.
Our Service
We pledge to treat every client with integrity and equality, regardless of contract size or whether they are domestic or international, new or existing customers, providing professional consultation and advice. Goldhome provides professional installation, commissioning and training for users' workers, ensures that users can get familiar with operation methods and put machines into use as soon as possible.
Key Components of a VLF Hipot Tester:
1.VLF AC Source:Generates the sinusoidal AC waveform at 0.1 Hz or 0.01 Hz.
2.Voltage Booster/Transformer:Steps up the voltage to the required test level (e.g., 2U₀, 3U₀, up to 50kV, 100kV, or more).
3.Control Unit:A digital interface to set test parameters (voltage, frequency, test time).
4.Measurement and Detection System: Precisely measures the output voltage and current, and detects breakdowns.
5.Safety Interlocks:Critical safety features to protect the operator.
The Feature of VLF Hipot Tester
Compact size, lightweight, and highly portable
- Advanced technology: it can realize fully automatic voltage boosting, stepping - down, measurement, and protection.
- Easy operation: The connection is simple, and it is easy to operate.
- Multiple protections: It has over - voltage protection and over - current protection on both the high - and low - voltage sides. The action time is no longer than 10 ms, ensuring the reliability of the test equipment.
- Safety and reliability: The control unit and the high - voltage booster have a low connection, with safe and reliable performance.
- Wide measurement range: Frequencies such as 0.1 Hz, 0.05 Hz, and 0.02 Hz can be selected, ensuring a wide measurement range.
- Full facilities: It is equipped with a capacitive touch screen, a large LCD screen, automatic storage function, and a built - in printer.
Compatible with tanδ and partial discharge (PD) detection for comprehensive insulation condition diagnosis.
How is it Used of VLF Hipot Tester?
A typical VLF test on a medium-voltage cable follows this pattern:
1.Safety:Ensure the circuit is de-energized, grounded, and proper lockout/tagout procedures are followed.
2.Connection:Connect the VLF tester's high-voltage output to the cable conductor. Connect the return lead to the cable shield or ground. Surround the area with safety barriers.
3.Setup:Program the test voltage (usually 2-3 times the cable's normal line-to-ground operating voltage, U₀) and the test duration (typically 15 to 60 minutes as per standards like IEEE 400.2).
4.Ramp Up:The tester gradually ramps the voltage from zero to the full preset test voltage.
5.Dwell Time:The voltage is held at the test level for the predetermined time.
6.Monitoring:The technician monitors the leakage current. A stable current indicates good insulation. A sudden, sharp increase in current indicates an insulation breakdown (failure).
7.Ramp Down & Ground:After the test time elapses, the voltage is ramped down to zero, and the internal system safely discharges the stored energy. The output is then grounded before disconnection.
Advantages of an Ultra-Low Frequency High-Voltage Generator
Standards
Compliance with standard IEEE 400.2, IEC 60502-2, and IEEE 433.
Volume and Portability
Utilizing low-frequency technology reduces power supply capacity requirements, significantly decreasing equipment size and weight.
Test Sensitivity
More uniform voltage distribution at low frequencies facilitates detection of end-insulation defects.
Load Capacity
Increased capacitive reactance at low frequencies enables testing of long cables or high-capacity equipment using low-power sources.
Automation and Functionality
Microprocessor control with automatic voltage ramping, timing, data storage, and waveform display.
Cost Efficiency
Substantially reduced equipment procurement, transportation, and installation costs.
VLF Hipot Tester Specification
1.Output voltage :80kv
2.Output frequency: 0.1Hz, 0.05Hz, 0.02Hz
3.Output voltage frequency errors: 3%
4.Output voltage peak errors: ≤ 1%
5.Output waveform distortion: ≤ 5%
6.Use condition: indoor and outdoor; temperature: -10℃~+50℃
7.Humidity: ≤ 85%RH
8.Power: AC 220V ±10%,50±5%Hz
9.Tested object:35KV and below voltage cable, generator,transformer,ect.
|
Model |
Rated Voltage |
Load Capacity |
Power Fuse |
Product Structure and Weight |
|
30/1.1 |
30 kv (peak value) |
0.1Hz,≤1.1µF |
20A |
Controller: 6 kg Booster: 20 kg |
|
0.05Hz,≤2.2µF |
||||
|
0.02Hz,≤5.5µF |
||||
|
50/1.1 |
50 kv (peak value) |
0.1Hz,≤1.1µF |
20A |
Controller: 6 kg Booster: 45 kg |
|
0.05Hz,≤2.2µF |
||||
|
0.02Hz,≤5.5µF |
||||
|
80/0.5 |
80 kv (peak value) |
0.1Hz,≤1.1µF |
30A |
Controller: 4 kg Booster: 50 kg |
Working Principle:Using power electronics technology, the utility-frequency electricity is first converted to direct current, then inverted into an ultra-low-frequency alternating current signal of 0.1Hz. Finally, this signal is amplified by a transformer, enabling a compact set of equipment to generate a high-voltage, low-frequency output.
Ultra-low frequency AC waveforms: Sine wave, cosine square wave/trapezoidal wave are the most common.
VLF Hipot Tester Applications
|
Application Category |
Specific Equipment |
Purpose of Test |
|
Power Cables |
Medium & High Voltage Cables (XLPE, EPR, PILC), Splices, Terminations |
Withstand Test:Verify integrity after installation, during maintenance, and after repair. |
|
Rotating Machinery |
Large Motors, Generators, Stator Windings |
Insulation Assessment:Find weaknesses, contamination, and aging in ground wall insulation without DC damage. |
|
Switchgear & Substations |
Circuit Breakers, Bus Bars, Load Break Switches, Disconnect Switches |
Component Integrity:Verify the insulation strength of various assembled components. |
|
SpecializedIndustries |
Aircraft Wiring, Shipboard Cables, Military Equipment |
High-Reliability Maintenance: Ensure wiring integrity in critical, mobile, and harsh environments. |
|
Other Components |
Lightning Arresters, Surge Capacitors (with caution) |
Insulation Verification: Specialized testing of component integrity. |
Operation Modes:
1.Withstand Test: Routine maintenance,acceptance testing, post-repair verification.
2.Step Voltage Test: Investigating aged or suspect insulation.
3.Tan Delta (tan δ)：Condition assessment,trending, and predicting remaining life.
4.Return Voltage:R&D and critical asset analysis for utilities.
Alternate Names for the Equipment
- VLF Withstand Voltage Test System
- VLF Dielectric Test Set
- Motor Insulation VLF Tester
- Ultra‑Low Frequency Cable Hipot Tester
- Ultra-low frequency high-voltage generator
- Ultra‑Low Frequency Generator Hipot Tester
- VLF AC High‑Voltage Generator
- VLF Ultra‑Low Frequency High‑Voltage Generator
- Ultra‑Low Frequency Hipot Tester
- 0.1 Hz Ultra‑Low Frequency High‑Voltage Generator）
- Programmable Ultra‑Low Frequency High‑Voltage Generator
- Intelligent Ultra‑Low Frequency High‑Voltage Generator
- Ultra‑Low Frequency AC High‑Voltage Test Set
- Ultra‑Low Frequency Withstand Voltage Test Equipment
- Low‑Frequency High‑Voltage Generator
- VLF AC High‑Voltage Generator
- Ultra‑Low Frequency Cable Hipot Tester
Below are Some Well-known Manufacturers of VLF Hipot Testers
High Voltage Inc.
Based in the United States, the company has been producing VLF Hipot Testers since 1998, with products distributed to over 100 countries worldwide. It offers a full range of VLF AC withstand voltage testers, including models with peak voltages from 30kVac to 200kVac.
Wuhan Goldhome Hipot Electrical Co., Ltd.
Based in Hubei, China, this manufacturer of high-voltage testing equipment holds ISO 9001, ISO 45001, and ISO 14001 certifications. Its VLF Hipot Testers are available in multiple voltage ratings.
Huazheng Electric Manufacturing (Baoding) Co., Ltd.
Based in Baoding, Hebei, China, this manufacturer produces electrical testing equipment including insulation resistance testers and oil testers.
Wuhan Jiuhua Jing Ce Power Equipment Co., Ltd.
Based in Wuhan, China, this company provides diverse power testing equipment, including products such as the 30kV Ultra-Low Frequency High-Voltage Withstand Tester.
A Prominent Manufacturer of VLF Hipot Tester in 20 years, Professional Quality Technology, Supply Manufacture Price
FAQ
Q: 1. What is Very Low Frequency (VLF) testing?
A: It is a method for conducting withstand voltage tests and insulation diagnostics on capacitive loads such as medium- and high-voltage cables. It employs a 0.1 Hz or 0.05 Hz sine wave or cosine square wave as the test power source, replacing conventional power frequency (50/60 Hz) AC testing.
Q: 2. Why use 0.1 Hz rather than 50 Hz?
A: The primary objective is to reduce equipment size and weight. According to the formula P = ω × C × U², the equipment capacity is proportional to frequency (ω). Reducing the frequency from 50Hz to 0.1Hz theoretically decreases the required capacity by a factor of 500, rendering the tester exceptionally lightweight and portable for field applications.
Q: 3. Can VLF testing replace power frequency AC testing?
A: Yes, and it has become the recommended method for on-site cable withstand voltage testing in international standards (e.g., IEEE 400.2). Extensive research and practice demonstrate that VLF testing is equally effective as power frequency testing in detecting cable insulation defects (particularly water trees), while offering safer and more portable equipment.
Q: 4. What are the two primary VLF waveforms? What distinguishes them?
A: Sine Wave: The traditional standard waveform, matching the shape of power frequency sine waves, is more suitable for dielectric loss (Tanδ) diagnostic testing.
Cosine-Rectangular Wave: Easier to generate with lower equipment costs, but primarily used for withstand voltage pass/fail tests with weaker diagnostic capability. The current mainstream trend favours the sine wave.
Q: 5. What advanced features do VLF testers offer?
A: High-end VLF equipment integrates dielectric loss diagnosis (Tanδ) and partial discharge (PD) detection capabilities. This enables quantitative assessment of overall insulation ageing (water tree progression) during withstand voltage testing, facilitating condition-based maintenance.
Q: 6. In which scenarios is VLF testing primarily applied?
A: Primarily for on-site testing of extruded insulated cables (e.g., XLPE, PE, EPR)，Commissioning acceptance tests, preventive maintenance, and post-fault repair verification.
Q: 7. What should be done if breakdown occurs during testing?
A: The instrument will automatically cut off output and sound an alarm. Allow the instrument to fully discharge the cable automatically, then use a burn-through device or fault locator to precisely pinpoint and repair the fault location.
Q: 8. Does the equipment require calibration?
A: Yes. The accuracy of the output voltage and measurement circuit must be periodically verified. Calibration by a professional institution or manufacturer is recommended every 1-2 years.
Q: 9. What are the primary advantages and disadvantages of VLF testing?
A: Advantages:
Lightweight and portable; minimal impact on insulation integrity; integrated Tanδ testing for insulation ageing assessment.
Disadvantages:
Primarily confined to cables; relatively limited application scope.
Extended testing duration: a standard withstand voltage cycle requires 15-60 minutes.
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