1. Industry Demand Background of GIS and High Voltage Cable Field Testing
In global overseas power engineering projects, after the completion of the laying of 220kV GIS gas-insulated switchgear and 110kV~220kV XLPE high-voltage cross-linked cables, on-site AC withstand voltage tests are required to verify the overall insulation performance of the equipment. This is an essential testing procedure before the power grid is put into operation. Many overseas EPC contractors and third-party power testing agencies regularly purchase 300kV 200kVA withstand voltage testing equipment for GIS gas chamber withstand voltage, main circuit power frequency withstand voltage, and full-length AC withstand voltage testing of cables.
Due to limitations such as limited temporary power supply capacity at overseas construction sites, confined transportation space, and complex operating environments at outdoor substations, traditional integrated power frequency withstand voltage test transformers are bulky, have high power supply requirements, and are difficult to adapt to on-site scenarios. Addressing this industry pain point, DEMIKS Power (Shanghai DEMIKS Power) has launched a standardized 300kV/200kVA AC Resonant Test System , becoming the preferred equipment for withstand voltage testing of GIS and high-voltage cables overseas. 90% of international power transmission and distribution projects use the series resonant scheme to replace traditional power frequency withstand voltage devices.
2. Customer’s core test objects and mandatory parameter requirements
DEMIKS, based on the high-frequency procurement needs of global customers, has identified two core testing scenarios for test samples. The complete 300kV/200kVA series resonant system can cover all testing requirements in one stop:
2.1 Testing of 220kV HV GIS High-Voltage Gas-Insulated Switchgear
Applicable scenarios: GIS factory type withstand voltage test, field acceptance withstand voltage test, covering main circuit power frequency withstand voltage, disconnector/grounding switch insulation withstand voltage, independent gas chamber overall withstand voltage, 220kV GIS acceptance test standard maximum test voltage not exceeding 300kV, fully matching the output level of this set of frequency converter series resonant system.
2.2 Testing of 110kV~220kV HV XLPE High Voltage Power Cables
Applicable scenarios: AC withstand voltage test for cable laying completion and handover, preventive insulation testing. Long-distance, high-capacity high-voltage cables are typical capacitive loads. The frequency converter series resonant device relies on the resonant voltage boosting principle to significantly reduce the power supply requirement and is perfectly suited for withstand voltage testing of ultra-long cables.
Customer’s hard technical specifications:
Maximum AC output test voltage: AC 300kV (RMS, 50Hz/60Hz, customizable frequency conversion output)
The system’s rated output capacity is 200kVA, with a capacity margin of over 10% to ensure stable voltage boost over extended periods.
Equipment form factor: Split-type modular portable structure, primarily designed for on-site testing at outdoor substations; laboratory factory testing is a secondary application scenario.
3. Comparison of two mainstream pressure-resistant equipment solutions from DEMIKS (Recommended for export selection)
For the withstand voltage testing needs of 300kV/200kVA GIS + high-voltage cables, DEMIKS offers two mature complete solutions. The technical team prioritizes the frequency conversion series resonant test system , while the traditional dry power frequency withstand voltage test device is only an alternative for small and simple projects.
Option 1: 300kV/200kVA (Preferred for overseas projects)
The complete DEMIKS frequency converter series resonant withstand voltage device consists of a frequency converter power supply, excitation transformer, high-voltage resonant reactor group, 300kV capacitor divider, and optional compensation capacitors. The entire set is modular and easy to disassemble, making it convenient for export by sea with fumigation in wooden boxes.
a.) Variable frequency drive power supply: Rated input 380V/415V three-phase mains power, 0~400V adjustable variable frequency output, rated power 60kW, serving as the frequency and voltage regulation drive source for the entire resonant system; supports 50Hz/60Hz power grid modification, adaptable to different power grid standards in Europe, Southeast Asia, and the Americas.
b.) Excitation step-up transformer: input 0~400V, output 10kV, rated capacity 200kVA, matched with the input voltage of the resonant reactor to achieve primary voltage boost.
c.) High-voltage resonant reactor: Each reactor section is rated at 50kV/35kVA, and 6 sections are connected in series to achieve a total output voltage of 300kV. The total system capacity is 210kVA, which meets the 200kVA rated capacity margin. The reactor adopts a lightweight epoxy casting structure, and a single person can carry a single module.
d.) 300kV pure capacitor high voltage divider: voltage measurement accuracy ≤1%, equipped with intelligent digital display control system, integrating multiple protection functions such as overvoltage, overcurrent and breakdown, and real-time acquisition of high voltage test data.
e.) Compensating capacitor (optional): For supplementing and matching capacitive loads of large-section, ultra-long 220kV high-voltage cables, no configuration is required for routine GIS testing.
DEMIKS Variable Frequency Series Resonant Core Industry Advantages (Key Focus for Foreign Trade Customers)
a.) Compatible with all product categories: It is suitable for both small capacitive loads of GIS and ultra-large capacitive loads of long-distance high-voltage cables, and complies with international testing standards such as IEC62271 (GIS switches), IEC60840, and IEC62067 (high-voltage cables), meeting the type test review requirements of global third-party testing organizations.
b.) Low on-site power supply threshold: Only 60kW of external mains power is required to achieve 200kVA high voltage output, saving more than 70% of power supply capacity compared with traditional power frequency withstand voltage devices, and is suitable for the power supply conditions of temporary small generator sets on overseas construction sites.
c.) Modular export-friendly: Each component is individually packaged in a wooden crate, which can be loaded into a standard container for sea freight. It is easy to assemble and disassemble, which greatly reduces international logistics costs.
d.) High safety factor in testing: The resonant circuit detunes instantly upon test sample breakdown, the high voltage drops rapidly, and the short-circuit current is extremely small, preventing damage to GIS and cable insulation test samples; the output is a standard sine wave with no harmonic spikes, avoiding false breakdown.
Option 2: 300kV/200kVA Traditional dry-type power frequency withstand voltage test device (optional, not recommended)
The DEMIKS dry-type power frequency withstand voltage complete set of equipment includes: a 300kV/200kVA dry-type test transformer, a 220kVA high-power induction voltage regulator, a 300kV capacitor divider, and a complete set of high-voltage accessories.
Shortcomings of the solution
The entire set of equipment has an input power of nearly 200kVA, and overseas construction sites need to be equipped with a high-power and stable power supply. The equipment is large in size and weight, and the power consumption of long-distance high-voltage cable withstand voltage test is high and transportation is difficult. It is only suitable for simple tests of small GIS with short test samples, and is rarely used in large overseas cable projects.
4. Confirmation of 5 key pieces of information before customizing foreign trade orders (DEMIKS standardized inquiry process)
To ensure precise customization of the 300kV/200kVA variable frequency series resonant device, DEMIKS sales engineers will verify five core parameters in advance to avoid equipment compatibility deviations:
a.) The frequency of the national power grid where the project is located is 50Hz (mainstream in Asia and Europe) / 60Hz (Southeast Asia and America), and the internal program of the frequency converter will be modified accordingly.
b.) The maximum length of a single section of the high-voltage cable under test is used to calculate the capacity margin of the reactor.
c.) On-site testing of GIS rated voltage level (110kV/220kV).
d.) Local three-phase power input standard: 380V or 415V;
The project shall be conducted in accordance with the following testing standards: IEC international standards or local power industry regulations.
5. DEMIKS Foreign Trade Complete Set Business Delivery Standards
All exported 300kV frequency converter series resonant withstand voltage systems are accompanied by a standardized Commercial Offer document, including itemized details and the total price of the entire unit: the frequency converter power supply, excitation transformer, high-voltage reactor group, capacitor divider, high-voltage connection line, equalizing sphere, grounding cable and other accessories are quoted separately; trade terms can be selected as FOB Shanghai, FOB Ningbo or CIF destination port; the standard international warranty period is 18 months, and the standard delivery time is 15-25 working days; the equipment is packaged in IP65 protected fumigated solid wood export wooden crates, which are moisture-proof and shockproof, suitable for long-term ocean shipping.
6. Overall Strength of DEMIKS High Voltage Testing Equipment
Shanghai DEMIKS Power specializes in the research and development and manufacturing of a full range of high-voltage power testing equipment. Its product line covers variable frequency series resonant withstand voltage devices, power frequency withstand voltage testing equipment, fully automatic temperature rise testing systems, SF6 gas recovery and purification devices, lightning impulse voltage generators, and other complete sets of high-voltage testing instruments. Its products are widely used by leading domestic power grid companies and national-level power research institutes, and are also exported in bulk to power engineering EPC contractors and third-party testing laboratories in dozens of countries in Southeast Asia, the Middle East, Europe, and Latin America.
All DEMIKS high-voltage testing equipment is CE certified. The hardware and software are entirely independently developed, and customized high-voltage withstand voltage solutions can be provided based on customer’s site conditions. Professional engineers provide full-process pr-sales technical selection, on-site testing guidance, and after-sales remote technical support. For GIS or high-voltage cable AC withstand voltage equipment procurement needs, please send an email to contact@demikspower.com to obtain detailed technical solutions and quotations.
In overseas 220kV GIS substation construction and high-voltage cable laying projects, a lightweight, low-power-demand 300kV 200kVA variable frequency series resonant withstand voltage system is a core tool to ensure efficient insulation testing. DEMIKS continuously optimizes the structure and control algorithm of its AC Resonant Test System, providing the global power industry with cost-effective, IEC-compliant high-voltage withstand voltage testing equipment, offering a one-stop solution for on-site AC withstand voltage testing of GIS and XLPE cables.
