Partial discharge detector
Updated 2026-10-27
Data records
- On a cable the detector reports the position of each discharge site along the route; the position is derived from the time between the direct arrival of a pulse at the detector and the arrival of its reflection from the far end of the cable.
- Before a measurement a calibrator injects pulses of known charge and selectable polarity across the terminals of the test object, so that the detector readings are scaled in apparent charge, and the software records the calibration.
- In the conventional electrical method a coupling capacitor is connected in parallel with the test object and a measuring impedance in series with it converts the partial discharge current pulses into voltage pulses for the detector, with the coupling capacitor and measuring impedance chosen for the test object.
- A high-frequency current transformer is a split-core inductive sensor clamped around a ground connection, or around the low-voltage end of a coupling capacitor or test object, that picks up partial discharge pulses over a wide frequency band.
- Flexible digital filters let the measuring band be moved to a quieter part of the spectrum and reject noise tied to particular frequencies, so that real partial discharge is told apart from interference.
- An offline measurement requires the cable to be taken out of service and energized from a separate test source, while an online spot test measures during normal operation through high-frequency current transformers or couplers on voltage detecting sockets, without switching the cable off.
- A phase-resolved partial discharge pattern plots each pulse against the phase angle of the test voltage at which it occurred, and the shape of the pattern serves as a fingerprint for identifying the type of defect.
- Several detector units are synchronized over fiber-optic links, which isolates the measuring hardware from the high-voltage circuit, so that pulses are correlated across channels to locate discharge sites in cables and to separate internal from external sources in transformers and rotating machines.
- Beyond the charge-based method, a detector works with ultra-high-frequency sensors and transient earth voltage probes, and with direct-voltage and very-low-frequency sources, so that partial discharge can be measured on gas-insulated switchgear, cables and machines in the field.
Elsewhere in the family
- Partial Discharge Offline related entry on Electrical Testing Reference
- Partial Discharge Offline related entry on Motor Testing Reference
- Partial Discharge Online related entry on Electrical Testing Reference
- Partial Discharge Online related entry on Switchgear Testing Reference
- Partial Discharge Online related entry on Transformer Testing Reference
Sources
- b2 electronic product page, VLF Diagnostics Systems - PDTD series, web page edition, b2 electronic. Held as: Public page. Publisher page
- BAUR product page, PD-TaD 62 portable PD diagnostics system, web page edition, BAUR. Held as: Public page. Publisher page
- BAUR product page, liona online PD spot tester, web page edition, BAUR. Held as: Public page. Publisher page
- Haefely product page, DDX 9160 Partial Discharge (PD) and Radio Interference Voltage (RIV) Detector, web page edition, Haefely (Pfiffner Group). Held as: Public page. Publisher page
- Haefely product page, HFCT - High Frequency Current Transformer, web page edition, Haefely (Pfiffner Group). Held as: Public page. Publisher page
- OMICRON product page, MPD 800 - Universal partial discharge measurement and analysis system, web page edition, OMICRON electronics. Held as: Public page. Publisher page
Changelog (22 entries)
| Date | Revision | Change |
|---|---|---|
| 2026-10-27 | created (instr.partial-discharge-detector.cable-pd-location) | |
| 2026-10-27 | revised (instr.partial-discharge-detector.cable-pd-location) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.partial-discharge-detector.cable-pd-location) | |
| 2026-10-27 | created (instr.partial-discharge-detector.charge-calibration) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.partial-discharge-detector.charge-calibration) | |
| 2026-10-27 | created (instr.partial-discharge-detector.conventional-method) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.partial-discharge-detector.conventional-method) | |
| 2026-10-27 | created (instr.partial-discharge-detector.hfct-sensor) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.partial-discharge-detector.hfct-sensor) | |
| 2026-10-27 | created (instr.partial-discharge-detector.noise-suppression) | |
| 2026-10-27 | revised (instr.partial-discharge-detector.noise-suppression) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.partial-discharge-detector.noise-suppression) | |
| 2026-10-27 | created (instr.partial-discharge-detector.online-versus-offline) | |
| 2026-10-27 | revised (instr.partial-discharge-detector.online-versus-offline) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.partial-discharge-detector.online-versus-offline) | |
| 2026-10-27 | created (instr.partial-discharge-detector.phase-resolved-pattern) | |
| 2026-10-27 | revised (instr.partial-discharge-detector.phase-resolved-pattern) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.partial-discharge-detector.phase-resolved-pattern) | |
| 2026-10-27 | created (instr.partial-discharge-detector.synchronous-multichannel) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.partial-discharge-detector.synchronous-multichannel) | |
| 2026-10-27 | created (instr.partial-discharge-detector.uhf-and-tev-sensors) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.partial-discharge-detector.uhf-and-tev-sensors) |
Cite this page
Cite the governing standard for the fact itself; cite this page as the finding aid.
"Partial discharge detector." Test Instrument Reference. 2026-10-27. https://www.testinstrumentreference.com/instruments/partial-discharge-detector/.
Test Instrument Reference, Partial discharge detector (Oct. 27, 2026), https://www.testinstrumentreference.com/instruments/partial-discharge-detector/.
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title = {Partial discharge detector},
howpublished = {\url{https://www.testinstrumentreference.com/instruments/partial-discharge-detector/}},
organization = {Test Instrument Reference},
publisher = {Test Instrument Reference},
year = {2026},
note = {last substantive change 2026-10-27}
}{{cite web |title=Partial discharge detector |website=Test Instrument Reference |publisher=Test Instrument Reference |url=https://www.testinstrumentreference.com/instruments/partial-discharge-detector/ |date=2026-10-27 |access-date=}}