Test Instrument Reference

VLF test set

Updated 2026-10-27

Data records

  • On detecting a breakdown the set ends the test on its own, shuts down the high-voltage generator, discharges the test object and reports the voltage at which the breakdown occurred, and a ground-loop monitor stops the test when the ground connection is lost. Source: Megger product page, web page edition. Verified 2026-10-27. Record instr.vlf-test-set.breakdown-detection-and-discharge
  • The set lowers its test frequency automatically as the capacitance of the connected cable increases, so that a long cable can be tested within the output capability of the set while the test voltage is maintained. Source: Megger product page, web page edition. Verified 2026-10-27. Record instr.vlf-test-set.frequency-adapts-to-cable-length
  • A VLF test set serves as the voltage source for an offline partial discharge measurement on a cable, so that partial discharge and tan delta can be measured at the same time without preconditioning the cable. Source: b2 electronic product page, web page edition. Verified 2026-10-27. Record instr.vlf-test-set.pd-source
  • A VLF test set applies an alternating test voltage at a frequency far below the power frequency for withstand testing of installed cables, motors, generators and other highly capacitive loads, and it serves as the voltage source for tan delta and partial discharge diagnostics. Source: High Voltage, Inc. product page, web page edition. Verified 2026-10-27. Record instr.vlf-test-set.purpose
  • The direct-voltage output of a VLF test set is also used for testing the outer sheath of a cable, and with a fault locating accessory a sheath fault can be pinpointed. Source: b2 electronic product page, web page edition. Verified 2026-10-27. Record instr.vlf-test-set.sheath-testing
  • An integrated dissipation factor function measures the tan delta of the cable with the VLF set as the voltage source, and a monitored withstand test combines the withstand test with the dissipation factor measurement so that the condition of the cable is assessed in one sequence. Source: BAUR product page, web page edition. Verified 2026-10-27. Record instr.vlf-test-set.tan-delta-add-on
  • The instrument class is written VLF test set. Value: VLF test set. Source: Electrical Testing Reference editorial taxonomy, 2026-10 edition. Verified 2026-10-27. Record instr.vlf-test-set.title
  • A VLF test set delivers a true sinusoidal test voltage, and a set may also provide a rectangular waveform and a direct voltage so that the voltage shape can be matched to the test object and the guide being followed. Source: Megger product page, web page edition. Verified 2026-10-27. Record instr.vlf-test-set.waveforms
  • The charging current of a capacitive load is proportional to frequency, so at a very low frequency the current and power needed to raise a long cable to test voltage are a small fraction of what a power-frequency set would need, which allows a VLF set to be small enough to carry. Source: High Voltage, Inc. product page, web page edition. Verified 2026-10-27. Record instr.vlf-test-set.why-low-frequency

Sources

  • b2 electronic product page, VLF Diagnostics Systems - PDTD series, web page edition, b2 electronic. Held as: Public page. Publisher page
  • b2 electronic product page, HVA28 / HVA28TD VLF test sets, web page edition, b2 electronic. Held as: Public page. Publisher page
  • BAUR product page, frida / frida TD VLF testing and diagnostics unit, web page edition, BAUR. Held as: Public page. Publisher page
  • Electrical Testing Reference editorial taxonomy, Electrical Testing Reference editorial taxonomy of test methods, 2026-10 edition, Electrical Testing Reference. Held as: Own observation.
  • High Voltage, Inc. product page, VLF AC Technology, web page edition, High Voltage, Inc.. Held as: Public page. Publisher page
  • Megger product page, VLF Sine Wave 45 kV - Cable Tester, web page edition, Megger. Held as: Public page. Publisher page
Changelog (24 entries)
DateRevisionChange
2026-10-27created (instr.vlf-test-set.breakdown-detection-and-discharge)
2026-10-27revised (instr.vlf-test-set.breakdown-detection-and-discharge)
2026-10-27review_status unreviewed -> software_reviewed (instr.vlf-test-set.breakdown-detection-and-discharge)
2026-10-27created (instr.vlf-test-set.frequency-adapts-to-cable-length)
2026-10-27revised (instr.vlf-test-set.frequency-adapts-to-cable-length)
2026-10-27review_status unreviewed -> software_reviewed (instr.vlf-test-set.frequency-adapts-to-cable-length)
2026-10-27created (instr.vlf-test-set.pd-source)
2026-10-27review_status unreviewed -> software_reviewed (instr.vlf-test-set.pd-source)
2026-10-27created (instr.vlf-test-set.purpose)
2026-10-27review_status unreviewed -> software_reviewed (instr.vlf-test-set.purpose)
2026-10-27created (instr.vlf-test-set.sheath-testing)
2026-10-27revised (instr.vlf-test-set.sheath-testing)
2026-10-27review_status unreviewed -> software_reviewed (instr.vlf-test-set.sheath-testing)
2026-10-27created (instr.vlf-test-set.tan-delta-add-on)
2026-10-27revised (instr.vlf-test-set.tan-delta-add-on)
2026-10-27review_status unreviewed -> software_reviewed (instr.vlf-test-set.tan-delta-add-on)
2026-10-27created (instr.vlf-test-set.title)
2026-10-27review_status unreviewed -> software_reviewed (instr.vlf-test-set.title)
2026-10-27created (instr.vlf-test-set.waveforms)
2026-10-27revised (instr.vlf-test-set.waveforms)
2026-10-27review_status unreviewed -> software_reviewed (instr.vlf-test-set.waveforms)
2026-10-27created (instr.vlf-test-set.why-low-frequency)
2026-10-27revised (instr.vlf-test-set.why-low-frequency)
2026-10-27review_status unreviewed -> software_reviewed (instr.vlf-test-set.why-low-frequency)

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Cite the governing standard for the fact itself; cite this page as the finding aid.

"VLF test set." Test Instrument Reference. 2026-10-27. https://www.testinstrumentreference.com/instruments/vlf-test-set/.