Why install a trip and lockout relay?
To prevent the enlargement of the accident caused by re-closing after a short-circuit trip, the tripping and blocking relay will act after a certain fault or short-circuit, keep it inside and send out a signal. If the fault point is not identified, the latching relay manufacturers operator cannot perform the closing again. The personnel cannot reset the relay, which is generally used in the high-voltage circuit. If it is repeatedly closed and tripped, it will expand the accident and impact the power grid, and the consequences will be more serious.
It actually refers to "self-locking", that is, after the du relay is energized, it automatically locks its state, even if the control current is disconnected at this time, it will not change its state, that is, when the power is turned on After disconnecting the control current, it will continue to maintain the pull-in state, unless the unlock button is pressed, (some are unlocked with reverse current)
Ordinary relays are all "monostable", and this type of relay is "bistable".