doble TDR900 - Breaker Features and Operation

Doble TDR900 User Guide
72A-2612-01 Rev. A 09/06
12
4.3 How a Breaker Operates
In an “open” operation, also called a “trip,” the breaker must:
• Have conducting elements which move apart
• Be extinguished when an arc develops between the contacts
• Have conductors which stay far enough apart for the arc not to “restrike” which
would allow current to flow again
In a “close” operation, the breaker must:
• Have conducting elements which move together
• Have conducting elements which then stay together with minimum bounce
• Become a conductor
4.4 Features of a Breaker
4.4.1 Tank
The mechanical parts of the breaker that perform the opening and closing functions will
be housed in a tank, or compartment. A breaker design where the tank is grounded is
called a “dead tank” breaker. Where the tank itself is at a voltage during breaker
operation, the breaker is known as “live tank.”
Usually live tank breakers have the tank supported by insulated columns and located at
some elevation above substation ground level where the control cabinet is housed.
4.4.2 Source of Energy
The action of a breaker is mechanical – the moving apart, or separation, of conducting
elements.
This movement can be achieved in a number of ways, including:
• Through operation of a coiled spring
• Through pneumatic action