PSP 2

Interrupting a low inductive current may lead to

• Very high restriking voltage
• Very high current
• Rupture of circuit breaker
• Current chopping

Current chopping can be avoided by

• Resistance switching
• Inductive switching
• Capacitive switching
• Diode switching

Recovery voltage is the value of the r.m.s. voltage that re-appears across the poles of a circuit breaker before

•  Restriking voltage
• Final arc distinction
• Rise of voltage
• All of these

Time between separation of contacts and energisation of trip coil is called

• Opening time
• Closing time
• Arching time
• Decaying time

Which of the following is not a protective gear?

• Fuse
• Circuit breaker
• Relay
• Thermister
• None of these

Quantity of oil in bulk oil circuit breakers increases with

• Decrease in voltage
• Increase in voltage
• Pressure of arc
• Mechanical stresses

Rating of circuit breaker depends upon

• Breaking capacity
• Making capacity
• Short time capacity
• All of these

Phenomenon of arc interruption takes place at

• Zero voltage
• Zero current
• High current
• High voltage

Symmetrical breaking current is

• Peak value of a.c. component
• Average value of a.c. component
• R.m.s. value of a.c. component
• All of these

Main disadvantage (s) of oil circuit breaker is that it

• Is easily inflammable
• May from an explosive mixture with air
• Requires maintenance
• All of these