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Explain a Dashpot used as a Time Delay device in Over load trips

Dash pot:
Dashpots are fitted for overload trips to get time delay action, so that breaker will not be opened, due to momentary current surge.
When load current is in excess, it attracts plunger of the solenoid.
Plunger or piston moves up against the displacement of viscose oil or silicone fluid, through a small hole on the piston.
Time lag depends upon hole size, and viscosity of oil.
Load current setting for trip is about 25% above maximum, but should not exceed 50%.

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