Method and apparatus for measuring the opening time of a medium voltage air circuit breaker
AssigneeChevron U.S.A. Inc.
InventorJohn P. Sands
Life of this patent
Estimating the term…
Abstract
A circuit and method for measuring the switch opening time, in cycles, of a medium voltage air circuit breaker. The circuit senses DC current feeding the trip coil in the circuit breaker. The timer starts a predetermined programmable time interval after the DC current starts flowing in the breaker trip coil circuit. The timer stops when the DC current stops flowing in the breaker trip coil circuit. The programmable time interval is a delay between the opening of the breaker's primary contacts and the opening of the trip coil circuit switch, and is used to determine the circuit breaker opening time from the starting and stopping of the timer. The timing device does not require connection to the circuit breaker's main power contacts.
Claims16
A timing device for measuring the switch time of a circuit breaker, comprising:
- sensing means for sensing a DC current flowing through a trip coil in the circuit breaker;
- and
- timer starting means for causing a timer to start a predetermined time period after the sensing of the DC current;
- and
- timer stopping means for stopping the timer when the DC current stops flowing through the trip coil to measure the switch time of the circuit breaker.
A method for measuring the switch time of a circuit breaker, comprising the steps of:
- sensing a DC current flowing through a trip coil in the circuit breaker;
- starting a timer a predetermined time period after the sensing of the DC current;
- and
- stopping the timer when the DC current stops flowing through the trip coil to measure the switch time of the circuit breaker.
An apparatus for measuring switch time of a circuit breaker comprising:
- a detection circuit which senses current flowing through a trip coil in the circuit breaker and generates a start signal and a stop signal responsive thereto;
- and
- a counter circuit for starting and stopping a timer in response to said start and stop signals, respectively, from said detection circuit.
Dependencies are inferred from the claim text.