What is an 86 Relay?
The 86 relay is a latching auxiliary relay that trips & disables a circuit breaker (or numerous breakers) during a serious malfunction.
Once operated, it remains locked in the tripped position unless manually reset by an operator.
Purpose of 86 Relay
Following a major fault, it ensures that the breaker is not automatically closed again until the problem is resolved.
It prevents malfunctioning equipment from being re-energized accidently.
It collects signals from protective relays (ex: overcurrent, differential, distance) and sends a master trip to the breaker.
It is frequently connected to alarm circuits to alert operators about system issues.
Applications of 86 Relay
- Power plants
- Substations (HV/EHV systems)
- Industrial protection systems
Practical Example
If the differential relay (87) (or) overcurrent relay (50/51) detect a malfunction, they transmit a signal to the 86 relay.
The 86 relay operates by tripping the breaker, locking it in the off position, displaying an alert, and requiring manual reset before re-energizing.
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