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VLF insulation testing

VLF Meter – VLF stands for “Very Low Frequency”, i.e. frequencies of 0.1 Hz and below. Electrical cables and wires are usually subjected to a DC test for fault diagnosis. However, such tests can damage the insulation of the cable. A VLF test is different, because it indicates that the insulation is not intact without damaging a cable or line. It is very easy to use the VLF meters from WGM Support.

The VLF meters generate an AC sine wave voltage waveform at a low frequency of 0.1 Hz or less. When used, the test voltage is applied for the desired duration during which the DUT either maintains the voltage or collapses. Thus, a VLF tester is recommended for a variety of applications. Depending on the equipment of the VLF testers, the cable test or cable diagnosis is performed. In general, VLF meter are used to check or diagnose cables.

VLF Meter M-VLF28 | Cable Test

VLF Meter Device M-VLF28 | Cable Test

VLF Meter M-VLF28 is suitable for cable testing and cable diagnosis. If a fault in the cable networks of the medium and low voltage range causes a malfunction, quick localization is important. Eliminating the supply interruptions is immensely important. Because it saves time, money and trouble. Besides that, the advantages of VLF testing have been confirmed by scientific studies and practical field tests. Also, the VLF test is recommended by the DIN VDE standards and the standardization of the IEEE 400.

Testing medium voltage cables or rotating machines and transformers has never been easier. If a fault occurs, high-tech equipment should be available to perform the necessary measurements. In fact, prerequisite for this is state-of-the-art technical measuring equipment. The VLF measuring device M-VLF28 has manual and automatic test settings. Additionally, the diagnostic sequences offer different operating modes: such as the VLF cable test with symmetric AC voltage. But this is load independent over the whole range. Furthermore, a second option is the test with DC with positive and negative polarity or burning in case of high-impedance faults. Overall, cable sheath test as well as the sheath fault location are possible.

On top, for the discharge of test specimens, a discharge device is available. This device enables both electronic and mechanical discharge of the test specimen. Moreover, the VLF test device can be extended with an internal Tangens Delta diagnostic unit at any time. With a weight of only 14kg the high voltage generator is the smallest device on the market and is perfectly suited for mobile use. At that, a waterproof, shockproof and dustproof IP67 housing protects the M-VLF28. All in all, these features make the VLF Meter M-VLF28 an outstanding cable testing and cable diagnostic device.

We are offer you advice on the topics of:
VLF Measuring Instruments | Cable Diagnosis | VLF Diagnosis.

VLF Measuring M-VLF34 | Cable Test

VLF Meter device M-VLF34 | cable test

VLF Meter M-VLF34 | Cable Testing – The field of work of the M-VLF34 is cable testing and cable diagnosis. The high voltage generator is a very compact and very light VLF test instrument. With the variable VLF system, it is possible to select the two polarities accordingly the mode DC testing and the AC output frequency. Cable sheath testing or sheath fault location are part of the selection range. M-VLF34 is a portable generator that generates high voltage to eliminate cable faults.

For the 0.1Hz VLF test system is suitable for medium voltage cable testing. VLF meter type M-VLF34 is a portable system for cable diagnosis and testing. A high output current up to 85mA is considered the special strength of the device. The powerful output is able to drive capacitive loads up to 15 microfarad. Weighing only 45kg, the high voltage generator is a compact VLF unit, making it perfect for mobile use. Due to its light weight, the site of operation can be easily reached.

With a maximum output voltage, it is possible to test a cable with a length of up to 8 km. M-VLF34 can also be extended to a cable diagnostic system due to its full modularity. Also, the system offers different operating modes. A built-in discharging device is available for discharging the DUTs. The M-VLF34 has a manual and automatic test diagnostic sequence. No external PC is required on site. Due to the fact that the VLF measuring device is not thermally limited, it can be operated continuously over the entire operating time.

We offer you advice on the following topics: VLF measuring devices | cable diagnostics | VLF diagnostics.

VLF Measuring M-VLF60 | Cable Diagnostics

VLF Meter M-VLF60 | Cable Diagnostics

VLF Meter M-VLF60 | Cable Testing | VLF Testers – Testing medium voltage cables with the M-VLF60 is easier today than it was many years ago. A VLF test finds faults in your cable system at much lower voltage than a conventional DC test. Thus, no traveling cells are generated. The M-VLF60 is a compact and, thanks to its robust design, extremely field-proof test system for medium voltage cables. No external PC is required on site. Fast commissioning and the possibility of true continuous operation qualify the unit as an ideal tool for routine cable testing.

With the portable VLF meter M-VLF60 you can test the following cables XLPE, PE & EPR. The VLF tester series finally allows utilities and industry an economical alternative to DC testing. To protect the operator and the equipment, the device has two independent discharging devices and an integrated 12kV reverse voltage protection (50 Hz). Thus, the software allows easy report generation. Also, the fast programming of test sequences. VLF stands for Very Low Frequency, 0.1 Hz and below.

Thus, it is an alternating voltage at low frequency. A VLF test system is simple to operate and the test is easy to perform. Conventional AC voltage test equipment has been used for decades for many types of installations. The test voltage is applied for the desired duration. This is because the DUT holds the voltage and either passes or fails. It is a pass/fail test. Why VLF testing? Because DC tests damage the insulation of the cable. That way, VLF testing shows the damage of the insulation without harming the cable.

We offer you advice on the topics of: VLF meter devices | cable diagnosis | VLF diagnosis.

VLF Meter M-VLF90 | VLF Test Equipment

VLF Meter M-VLF90 | VLF Test Equipment

VLF Meter M-VLF90 | sheath fault diagnosis – In case of cable testing or cable diagnosis in the field of medium voltage, portable and lightweight VLF devices are advantageous. Testing of cables with the M-VLF90 is possible up to a length of 33km. The output is capable of driving capacitive loads of 10 microfarad. Or a cable length of about 33km at 10 microfarad. Thus, one can test a cable of length up to 33km at maximum output voltage.

However, due to the variable output frequency, it is also possible to test much longer cable distances. In everyday life, cable testing or cable diagnosis can be easily managed with the VLF90. The VLF Meter M-VLF90 can be used for sheath testing or diagnosis. This makes the VLF90 suitable as a sinusoidal voltage source. Without an additional voltage source, the system can then be expanded to tan delta measurement. VLF90 is a compact high voltage test system for cable testing of medium voltage cables. Weighing only 127kg, it has an excellent power-to-weight ratio.

All in all, the VLF system offers various operating modes. A built-in discharging device is available for the DUTs to discharge. The M-VLF90 has a manual and automatic test and diagnostic sequence. Locally, the unit stores all results. On the one hand, no external PC is required. On the other hand, it is possible to use a USB stick to transfer the data to the software on the external PC. The VLF measuring device is not thermally limited. Therefore it can be operated continuously over the entire operating time.

We offer you advice on the following topics: VLF measuring devices | cable diagnostics | VLF diagnostics.

VLF Meter M-VLF120 | Cable measurement

VLF Meter M-VLF120 | Cable measurement

VLF Meter M-VLF120 | Cable Diagnostics – For both cable testing or cable fault diagnostics, the VLF Meter M-VLF120 has by far the best line-to-weight ratio in its class. VLF systems are used to check medium voltage cables or perform periodic cable testing. It is important to perform a reconnection check after repairs and work on power cables. In addition to the variable VLF (AC) output frequency, modes for DC voltage testing can also be selected. As well as cable sheath testing or sheath fault location. During the entire measurement time, the cable ends must be protected against direct and indirect contact.

The M-VLF120 system has an electronic as well as a mechanical discharge device (internal). On top it has an integrated 12kV reverse voltage protection. All of our high voltage series devices are “dry” systems, so they do not use oil. Consequently, this makes them very easy to maintain. Therefore, they are not subject to limited operating time. M-VLF120 is also expandable with a tangent delta diagnostic system. And a partial discharge diagnostic system (option). Thus, the M-VLF120 is a powerful 0.1 Hz VLF meter for medium voltage cable testing.

The M-VLF120 high voltage generator offers several operating modes:
cable test – cable sheath test – sheath fault location.

Furthermore, the measurement of capacitance and effective resistance of the DUT. Display of the current test time. Real-time indication of the output signal on the display. Plus, an intuitive operating software with language selection. Logging of measurement results. Protocol output via RS232 or USB optional. As well as a PC software for analysis and archiving. Breakdown detector and fast shutdown. Measurement of breakdown voltage. But also, the time optimized burning mode. Finally, low maintenance due to dry, oil-free design.

We offer you advice on the topics of: VLF measuring devices | cable diagnosis | VLF diagnosis.