Circuit Breakers Part 4
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Attempt Free Circuit Breakers Part 4 Here. Read The Important Electrical MCQ From Below.
Circuit Breakers Part Four (Fill In The Blank)
A sudden short-circuit in an ac system causes a rise in __________ in the short-circuited phase.
Answer: Current
The voltage appearing across the circuit breaker pole after final current zero is called __________ voltage.
Answer: Recovery
Thermal ionization of gases occurs at temperature around __________ C.
Answer: 3000
Circuit Breakers Part 4
The electron emission from contact surface caused by incidence of light energy is called __________.
Answer: photo-emission
De ionization can take place by the processes of recombination or attachment as well as by process of __________ and __________.
Answer: diffusion, drift
The behavior of arc in high vacuum is affected by contact material and __________.
Answer: conditions of the contact surface
Sphere gaps are used for measurement of __________.
Answer: high voltages
Current breakers are generally overhauled every __________ years.
Answer: three
Circuit Breakers Part 4
In circuit breakers, arc is extinguished either by __________ the arc __________ the arc or __________ the arc.
Answer: lengthening, cooling, splitting
Deterioration of dielectric oil is governed by __________ color.
Answer: dark
The characteristics of a fuse is governed by material and __________ of the fuse element.
Answer: shape
A fuse should generally have a normal rating 25 to 50 percent above the normal full load current to lake care of __________.
Answer: switching surges
Skin effect is absent in case of __________ current
Answer: direct
Insulators operate under __________ conditions.
Answer: no-load
Circuit Breakers Part 4
Melting point of aluminium is __________.
Answer: 657 C
Density of aluminium is nearly __________ of the density of copper.
Answer: one-third
Melting point of copper is __________ 0C.
Answer: 1083
Pantograph isolator is preferred for circuits above __________ kV.
Answer: 400
__________ current is the rms value of the current which a breaker must carry for a stated time.
Answer: short time
Circuit Breakers Part 4
The insulation requirements of switchgear are determined by __________ voltage.
Answer: transient
In horn gaps the arc is produced at the __________ during high voltage surge.
Answer: bottom
Secondary type lightning arresters are used for the protection of __________ transformers.
Answer: distribution
The non-linear resistor in lightning arrester offers __________ resistance to the flow of discharge currents and __________ resistance to power frequency voltage.
Answer: low, high
The most severe cause of switching over-voltages is __________.
Answer: closing of charged line
Circuit Breakers Part 4
__________ type lightening arresters are designed to discharge the switching over-voltage as well as lightning over-voltages.
Answer: magnetically blow out type
Traveling wave gets reflected from short circuited line with reflected current wave of __________ polarity and voltage wave of the __________ polarity.
Answer: same, opposite
Peterson coil is the reactance used in __________ earthing.
Answer: resonant
The phenomena of arcing grounds is commonly experienced with __________ systems.
Answer: ungrounded
In solid grounding system, the neutral is connected to ground without any __________ between neutral and ground.
Answer: intentional impedance
The grounding is generally at the __________ end.
Answer: supply
Insulation co-ordination of EHV and UHV line is based on __________.
Answer: switch over voltages
Circuit Breakers Part 4
In delta connected load, the line current return path. Hence line currents __________ zero sequence component.
Answer: do not have
The negative sequence network has only negative sequence __________.
Answer: reactance
The smallest value of actuating quantity at which protection starts operating in relation with the minimum value of fault current in the protected zone, is known as __________ of the protective scheme.
Answer: sensitivity
Trip circuit is normally a part of __________.
Answer: circuit breakers
The time elapsed between the instant of occurrence of fault and instant of final arc extinction in circuit breaker is known as __________.
Answer: fault clearing time
The time interval between occurrence of fault and closure of relay contacts is known as __________.
Answer: relay time
Circuit Breakers Part 4
The lime interval between closure of trip circuit and final arc interruption is known as __________.
Answer: breaker time
Acting ground is also known as __________ fault.
Answer: earth
Phase fault is __________ fault.
Answer: line to line
A relay which responds to increase in current is known as __________.
Answer: over current relay
Power line carrier is a __________ signal sent through the power line conductors.
Answer: high frequency
Static relays __________ moving parts.
Answer: do not
An electro-magnetic relay will operate when operating force is __________ restraining force.
Answer: greater than
An electro-magnetic relay will operate when operating force is __________ restraining force.
Answer: greater than
Circuit Breakers Part 4
__________ is suitable for outdoor UHV and HV traction system.
Answer: Air blast circuit breaker
The drop off value to pick-up value of a relay is also known as __________.
Answer: holding ratio
The holding ratio of a relay is usually __________.
Answer: less than 1
A bimetal strip consists of two metal strips having different __________.
Answer: coefficient of thermal expansion
A directional relay senses __________.
Answer: power
Circuit Breakers Part 4