Phep 30 Switches And Switching Equipment Flashcards
Whenever a circuit which is carrying current is open ?
The current tends to continue to flow across the contact as they separate
The initial TPDT would normally be Used to identify a type of
Knife switch
The type of knife switch used to interrupt field current to generators and synchronous machines is a
Field switch
Disconnect switch are commonly used on 440 V or higher voltage circuits to
Isolate or ground electrical equipment or circuits, not in service
Of the following statements concerning mercury control switches the one that’s most nearly not correct ?
They are generally used only where the circuit voltage is 120 or less
The main difference between a circuit breaker and any kind of electrical switch is that the circuit breaker?
Opens automatically when current exceeds a predetermined limit
Which of the below statements does not correctly describe a meaning or method for quenching an arc
Reducing the Reluctance across the contact
A blowout coil would most most likely be found in?
An air magnetic circuit breaker
Of the following statements the one which most neatly describes what is meant by Trip operation is ?
The precedence which takes place over any closing operation
A trip free operation takes place if?
A circuit breaker is closed while the protection relay is energized
Circuit breakers are generally classified by ?
All of the above
Speed is a desirable quality during the tripping operation of a circuit breaker to ?
All three
The energy needed to rapidly open. The contact of most circuit breakers designed is usually provided by ?
Springs and gravity
Of the following statement concerning OCB’s the one which is not correct is ?
The AC arc is always extinguished during the first currents zero
The closing time of an old CB becomes more important when it is considered from the standpoint of ?
Synchronization generators
