Very Low Frequency AC Hipot Tester with Sine Wave Output 70KV - VLF-70KV

Very Low Frequency AC Hipot Tester with Sine Wave Output 70KV

Product Description

AC testing of cables and electrical apparatus is now easier than ever!

VLF (Very Low Frequency) Testers are suitable for testing power cables, transformers, switchgear, rotating machinery and other electrical apparatus.

The product combines modern advanced digital variable frequency technology and micro computer control together, therefore, it can realize the full automatic voltage boost, stepdown, measurement and protection as well as the manual intervention in the process of automatic voltage boost. The full electronic design ensures the small size and light weight. The big LCD screen ensures the clear and visual display, and can display the output sinusoidal wave form. The printer outputs test reports. In addition, the product has features as follows:

1. Data of current, voltage, wave form can be directly sampled at high voltage side, so the data is real and accurate.

2. Overvoltage protection: If the output exceeds the set limit of voltage, the instrument will shut-down to protect itself, the actuation time is less than 20ms.

3. Overcurrent protection: It is high-low voltage dual protection in the design, the accurate shut-down protection can be made according to the set value at high voltage side; If the current on low voltage side exceeds the rated current, the instrument will take shut-down protection, the actuation time are both less than 20ms.

4. A high voltage output protective resistor is provided in the voltage boost body in the design and this eliminates the need of additional protective resistor connected outside.

Technical parameters:
1. Output voltage ratings: 30KV, 40KV, 50KV, 60KV, 70KV, 80kV (peak)
2. Output frequency: 0.1Hz, 0.05Hz, 0.02Hz
3. Measurement accuracy: 3%
4. Positive and negative voltage peak errors: ≤ 3%
5. Voltage wave form distortion: ≤ 5%
6. Use condition: Indoor and outdoor; Temperature: -10C--+40C; Humidity: ≤ 85%RH
7. Power: AC50Hz, 220V +-5%
8. Power supply fuse tube: 10A

What is VLF?

VLF means 'Very Low Frequency' and 0.1Hz to 0.02Hz is considered to be very low frequency. VLF AC Hipot's output is a true sinusoidal AC voltage at 0.1 Hz, 0.05Hz or 0.02Hz rather than at power line frequency of 50 or 60 Hz. The output test voltage is AC voltage but only at a lower frequency.

Where are VLF hipots used?

VLF hipots are used to test high capacitance loads with AC voltage for proof testing. For site testing applications, use of huge and heavy line frequency/series resonant AC systems are not practical. Typical loads are cables, generators & motors, insulators, bushings, transformers, and any other high capacitance load requiring AC proof testing.

A large transformer or generator or long cable has a high capacitance. If these were to be proof tested at 50/60 Hz, it would take a very high power, huge, heavy and expensive testers and this is not practical for field use. VLF testers are AC (sine wave) hipots, only at lower frequency. It is now possible for utilities etc to test at site cable etc with AC voltage using a small, lightweight, economical unit.

600 times less power required for cable testing at 0.1 Hz than at 60 Hz
500 times less power required for cable testing at 0.1 Hz than at 50 Hz
2500 times less when 0.02 Hz is used.

It is undesirable to allow cable failures, hence a PASS/FAIL AC test is the best test.

By their very nature, cables will fail in installation or in service. VLF them for timely repairs and to minimize costs. A cable which is unable to hold 2 to 3 times its working voltage is not going to last long. VLF it and repair it, if it is faulty. A cable which is designed to carry AC voltage and is factory tested with AC voltage therefore it must be field tested with AC voltage.