Phase sequence indicator
Updated 2026-10-27
Data records
- The instrument is used wherever a three-phase supply feeds motors, drives or other electrical equipment, to confirm that the connections give the intended phase order.
- Phase rotation is verified at the supply before a motor is connected and again after a transformer bank or meter base is changed, because a motor run in reverse can destroy the driven equipment, as with a screw compressor whose internal oil pump does not pump backwards.
- A contact-type indicator is connected to the three line conductors with test probes or clips and reads the supply directly; the probes have an adjustable clamping range so that they make safe contact, including in industrial sockets.
- A phase sequence indicator shows the order in which the three line voltages of a three-phase supply reach their peaks, the phase rotation, as a positive (clockwise) or negative (counterclockwise) sequence.
- Beyond the sequence itself the instrument flags error conditions in the connection, such as a missing phase or an input connected to neutral or to protective ground.
- The result is shown as a rotating light pattern, with an arrow that lights for the positive sequence and a distinct audible signal for each sequence, so the phase order is read at a glance and can be photographed for a completion report.
- Some phase sequence indicators are rated for measurement category CAT IV and, with fully insulated wide-jaw clips, are suited to industrial applications.
- Some indicators also determine the direction of rotation of a three-phase motor: on a running motor without test leads, by sensing the motor from outside, and on a disconnected motor when the shaft is turned by hand; this serves motors whose shaft cannot be seen.
- A non-contact indicator clips onto the insulation of each of the three conductors and senses the phase by static induction, so the sequence is read without a metallic connection to a live conductor.
Elsewhere in the family
- Phase Rotation and Phasing related entry on Electrical Testing Reference
- Phase Rotation and Phasing related entry on Motor Testing Reference
- Phase Rotation and Phasing related entry on Switchgear Testing Reference
Sources
- Amprobe product page, PRM-6 Phase Sequence and Motor Rotation Tester, web page edition, Amprobe. Held as: Public page. Publisher page
- Extech product page, Extech PRT200 Non-Contact Phase Sequence Tester, web page edition, Extech. Held as: Public page. Publisher page
- Fluke application article, Don't run it backwards (phase rotation testing in utility power distribution systems), web page edition, Fluke. Held as: Public page. Publisher page
- Fluke product page, Fluke 9040 Phase Rotation Indicator, web page edition, Fluke. Held as: Public page. Publisher page
- Hioki product page, PHASE DETECTOR PD3129, web page edition, Hioki. Held as: Public page. Publisher page
Changelog (24 entries)
| Date | Revision | Change |
|---|---|---|
| 2026-10-27 | created (instr.phase-sequence-indicator.applications) | |
| 2026-10-27 | revised (instr.phase-sequence-indicator.applications) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.phase-sequence-indicator.applications) | |
| 2026-10-27 | created (instr.phase-sequence-indicator.before-connecting-motors) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.phase-sequence-indicator.before-connecting-motors) | |
| 2026-10-27 | created (instr.phase-sequence-indicator.contact-type) | |
| 2026-10-27 | revised (instr.phase-sequence-indicator.contact-type) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.phase-sequence-indicator.contact-type) | |
| 2026-10-27 | created (instr.phase-sequence-indicator.definition) | |
| 2026-10-27 | revised (instr.phase-sequence-indicator.definition) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.phase-sequence-indicator.definition) | |
| 2026-10-27 | created (instr.phase-sequence-indicator.fault-indication) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.phase-sequence-indicator.fault-indication) | |
| 2026-10-27 | created (instr.phase-sequence-indicator.indication) | |
| 2026-10-27 | revised (instr.phase-sequence-indicator.indication) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.phase-sequence-indicator.indication) | |
| 2026-10-27 | created (instr.phase-sequence-indicator.measurement-category) | |
| 2026-10-27 | revised (instr.phase-sequence-indicator.measurement-category) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.phase-sequence-indicator.measurement-category) | |
| 2026-10-27 | created (instr.phase-sequence-indicator.motor-rotation-direction) | |
| 2026-10-27 | revised (instr.phase-sequence-indicator.motor-rotation-direction) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.phase-sequence-indicator.motor-rotation-direction) | |
| 2026-10-27 | created (instr.phase-sequence-indicator.non-contact-type) | |
| 2026-10-27 | review_status unreviewed -> software_reviewed (instr.phase-sequence-indicator.non-contact-type) |
Cite this page
Cite the governing standard for the fact itself; cite this page as the finding aid.
"Phase sequence indicator." Test Instrument Reference. 2026-10-27. https://www.testinstrumentreference.com/instruments/phase-sequence-indicator/.
Test Instrument Reference, Phase sequence indicator (Oct. 27, 2026), https://www.testinstrumentreference.com/instruments/phase-sequence-indicator/.
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title = {Phase sequence indicator},
howpublished = {\url{https://www.testinstrumentreference.com/instruments/phase-sequence-indicator/}},
organization = {Test Instrument Reference},
publisher = {Test Instrument Reference},
year = {2026},
note = {last substantive change 2026-10-27}
}{{cite web |title=Phase sequence indicator |website=Test Instrument Reference |publisher=Test Instrument Reference |url=https://www.testinstrumentreference.com/instruments/phase-sequence-indicator/ |date=2026-10-27 |access-date=}}