VLF28

VLF28

VLF28

Product catalog summary
Introduction
High Voltage, Inc. specializes in designing and manufacturing high voltage test equipment for utility and industrial applications. Their product range includes VLF AC hipots, fault locators, AC and DC hipots, and more. This document focuses on the Mini VLF AC Hipot, specifically the VLF-28CM model, designed for testing underground residential distribution (URD) cables.
VLF Technology Overview
VLF stands for Very Low Frequency, typically 0.1 Hz or lower. VLF AC hipots output a true sinusoidal AC voltage at this frequency, making them suitable for testing cables, rotating machinery, and other high capacitance loads. The VLF method is preferred over DC testing due to its non-damaging nature to solid dielectric insulation and its effectiveness in exposing defects.
Product Specifications
The VLF-28CM model is compact, portable, and economical, designed for short-run cable testing up to 15 kV. It features:
  • Output: 0–28 kVac at 0.1 Hz
  • Load Rating: 0.4 μF or approximately 4000 feet of 15 kV class cable
  • Size & Weight: 15” w x 11.5” d x 22” h, 69 lbs. (73 lbs. with accessories)
  • Input: 120 volts, 60 Hz, 5 A peak, or 230 volts, 50/60 Hz, 2.5 A peak
Benefits of VLF Testing
VLF testing is advantageous because it requires significantly less power than traditional line frequency testing, making it practical for field use. It does not degrade cable insulation or inject harmful space charges. The VLF-28CM is particularly noted for its small size, ease of operation, and ability to test cables up to 15 kV effectively.
Applications and Recommendations
The VLF-28CM is suitable for testing various types of cables, with the capability to test up to 4000 feet of 15 kV cable. For longer cable runs, higher power models are recommended. The device can also be used in conjunction with a tan delta bridge to measure insulation quality over time.
Conclusion
The VLF-28CM offers a reliable and efficient solution for field testing of AC power cables, ensuring the integrity of installations and repairs. Its design and functionality make it a valuable tool for utilities and industries requiring high voltage testing.
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Catalog excerpts

VLF28-1

Mini VLF AC Hipot For URD Cable Testing Designed for Quick & Easy Short-Run Cable Testing You just installed or repaired a cable: Now what? How do you know the work and materials are good? There is only one sure way to know: VLF IT! The best way to expose defects in a cable is to AC hipot it using VLF technology. After any cable is installed or repaired, it should be VLF hipotted to insure the integrity of the insulation, splices, joints, etc. A hipot test, a megger, or a 24 hour soak test tell little about the quality of the installation or repair. The cable’s already down: VLF it before reenergizing. If the cable can’t hold 2 – 3 times normal voltage for the IEEE prescribed 15 to 30 minutes, find out now while you’re there to make the repairs. With the majority of failures due to deficiencies or installation damage, a VLF test is a must to guarantee the cable’s integrity. It’s quick, easy, and sure. Because of the damage DC voltage causes to solid dielectric insulation and due to its limited ability to expose many types of defects, most have quit DC testing or reduced the test voltages to levels that provide little information about the cable condition. A cable is designed for and carries AC voltage: it should be tested with AC voltage. Our affordable VLF-28CM enables quick and easy field testing of AC power cables. Small • Portable • Economical Model VLF-28CM 0–28 kVac @ 0.1Hz output 15” w x 11.5” d x 22” h, 69 lbs. With Accessories: 73 lbs. Can test up to 0.4μF load or approximately 4000 feet of 15kV class cable. High Voltage, Inc. produces the smallest, lightest, most economical VLF AC Hipots available. Now, for the first time ever, a VLF hipot is available that approaches the size and weight of DC hipots. The VLF-28CM is designed for short run, 15 kV and below, cable testing. Other models offer higher power and voltages for other cable and apparatus testing applications. These models range in voltage from 40 kV to 200 kV and in load ratings from 5.5 μF to 50 μF. Other applications include: rotating machinery per IEEE 433, capacitors, bushings and insulators, transformers, and other high capacitance loads. 31 County Rt. 7A • Copake, NY 12516 • (518) 329-3275 • Fax: (518) 329-3271 E-Mail: [email protected] • Web: www.hvinc.com High Voltage, Inc. designs and manufactures high voltage test equipment for utility and industrial applications. Products include VLF AC hipots, fault locators/thumpers, AC and DC hipots, aerial lift testers, HV dividers,

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VLF28-2

What is VLF? VLF stands for Very Low Frequency and is generally considered to be 0.1 Hz and lower. The HVI VLF AC hipots output a true sinusoidal AC voltage at 0.1 Hz and lower, rather than at 50 or 60 Hz. It is still AC voltage only at a lower frequency. A VLF hipot is simple to operate and VLF testing is easy to perform. AC hipots have been used for decades to test various types of equipment. Now they can be used for field testing cable, rotating machinery, and other loads. The load is connected to the HV output and the grounded return of the VLF unit. The test voltage is applied for the required...

 Open the catalog to page 2

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*Prices are pre-tax. They exclude delivery charges and customs duties and do not include additional charges for installation or activation options. Prices are indicative only and may vary by country, with changes to the cost of raw materials and exchange rates.