After a trip, the relay leaves latched targets (LEDs, display messages, flags), a lockout relay 86 that blocks closing may have operated, and the relay stores events and oscillography. Resetting means turning those targets off and releasing the lockout, not erasing the records. It is done only after noting the targets, downloading the records and understanding why it tripped, especially if the 86 operated.
What is left in the relay after a trip
When a protection trips, the relay does not return to its normal state by itself. Several things remain, and each is handled differently:
| What remains | Where it shows | How it is reset | What information it holds |
|---|---|---|---|
| Trip and function LEDs | Relay front panel | Reset button, command from the software or SCADA | Which function and which phases operated |
| Fault message on the display | Relay display | Reset or acknowledge button | Summary: function, phases, current, distance |
| Lockout relay 86 operated | Flag or handle on the panel, signal to SCADA | Manual at the front or electrical, depending on the design | That there was a serious fault in the zone |
| Internal logic lockout | Status on the display or in the software | Deliberate reset command | The same as the 86, inside the relay |
| SCADA alarms | Operator screen | Operator acknowledgment | Time-stamped log in the control system |
| Events and oscillography | Relay memory | Not reset: downloaded and, if needed, cleared afterwards | Everything needed for the analysis |
The most common confusion is thinking that resetting the relay “cleans” it. Resetting turns off targets and releases lockouts; the records stay in memory until they are overwritten or someone clears them with a specific command.
Why not reset immediately
The impulse in a stopped plant is to reset and close. The reasons not to:
- Targets are the first evidence. Which LED lit, in what order and on which relays tells you which protection saw the fault. If they are reset without being noted or photographed, the quickest reading of the event is lost.
- The 86 exists to prevent closing. It operates on serious faults: transformer differential, bus differential, breaker failure, transformer mechanical protection. Resetting it and closing without checking can re-energize equipment with an internal fault. We explain it in lockout relay 86.
- A trip without a clear cause happens again. If the trip was caused by a setting, a wiring fault or a saturated current transformer, the next close ends the same way or worse.
- Records can be lost. Recloses, new pickups or test operations take up memory and can overwrite the record of the original trip.
The recommended order
- 01Visual evidencePhotograph the relay front panels and note LEDs, messages and 86 flags
- 02AlarmsRecord the SCADA alarms with their time
- 03RecordsDownload events, oscillography and settings from the relays involved
- 04CauseIdentify which protection tripped and whether the fault is confirmed or ruled out
- 0586 lockoutIf it operated, inspect the equipment and obtain authorization to energize
- 06ResetReset targets and lockout, and check that they do not come back
What each record contains and how to interpret it is in sequence of events and event reports and in how to read an oscillography; how to download them for each brand, in downloading relay event reports and oscillography.
When to reset and when not to
- Did a lockout relay 86 or an equivalent logic lockout operate?
- YesWas the protected equipment inspected and an internal fault ruled out with tests or analysis?
- YesReset with authorization and energize following the company procedure
- NoDo not reset: inspect and test the equipment before energizing
- NoWas the cause of the trip identified from the records?
- YesReset targets and close following the operating procedure
- NoSave the records and analyze before closing, or close with the authorization of whoever takes the risk
On distribution networks with reclosing, a final trip after the reclose sequence means the fault was permanent or reclosing was not enabled. The cause lies in the line or in the logic, not in the reset.
Where it is reset from
The reset can be done from several places, and each site defines which ones it allows:
- At the relay front panel, with the reset key. It is the most common method for LEDs and messages. On some relays the same key also resets the internal logic lockout; on others, the lockout needs a separate command.
- At the front of the panel, with the handle or pushbutton of the physical 86.
- From the manufacturer’s software, with the operate access level. Each brand has its own commands to reset targets and lockouts and, separately, to clear records and counters.
- From the bay controller or SCADA, if the design provides for it and the company’s philosophy allows it.
A relay that asks for an access level to reset is not a nuisance: it prevents lockouts from being reset without authorization. If nobody knows the operate password, see relay access levels and passwords.
What not to do
- Clear memories to “clean” the relay. The records that explained the trip are lost.
- Change settings before analyzing. Raising the setting so it does not trip again can leave the equipment unprotected; besides, nobody will know which settings it acted with.
- Jumper the 86 or its contact in the close circuit to re-energize.
- Reset from the software without knowing what is being reset. Some software reset commands group targets, counters and records; read what each one does in the manual.
- Ignore an internal relay alarm. If the relay reports a fault of its own, its protection may not be reliable.
When to ask for an analysis
Ask for an analysis when the trip has no evident cause, when several protections or several voltage levels tripped at once, when the 86 operated without a confirmed fault, or when the same trip repeats. At Tiza Group we review your relay’s settings and logic remotely with remote relay configuration, and if you need a formal opinion on the event we will quote a relay trip analysis based on your events, oscillography and settings. If the equipment has to be tested before energizing, our team performs power transformer testing and tests on the rest of the primary equipment in the field, in Colombia, or elsewhere on request.
Related guides
- Lockout relay 86: what it is and how it works
- How to read a fault oscillography step by step
- Sequence of events (SOE/SER) and event reports
- Trip circuit supervision (74TC, TCS): how it works
- Protective relays: types, functions and maintenance
- How to connect to a protective relay: ports and software
- IEEE 1686: IED cybersecurity requirements
References
- IEEE C37.2-2022, Standard for Electrical Power System Device Function Numbers, Acronyms, and Contact Designations (device 86).
- IEEE C37.91-2021, Guide for Protecting Power Transformers.
- IEEE C37.233-2023, Guide for Power System Protection Testing.
- Relay manufacturers’ instruction manuals: target, reset and event recording sections.
Frequently asked questions
Does resetting the relay LEDs erase the oscillography?
In numerical relays, resetting targets and clearing records are usually separate commands, so resetting the LEDs normally does not erase events or oscillography. Confirm it in your model's manual and download the records before resetting: some maintenance commands do erase them.
Why does the trip LED come back on after I reset it?
Because the condition is still present: the protection is still picked up, a binary input is still active or there is an internal relay alarm. An LED that will not go out is information, not a nuisance. Check which signal is holding it before trying to reset again.
Can the 86 be reset from SCADA?
It depends on the company's philosophy and the panel design. Many utilities require a local reset of the 86, at the front of the panel, to force an inspection on site before re-energizing. If it is allowed from SCADA, who did it and under what authorization must be logged.