1 Answer

Answer :

H.R.C. fuses provide best protection against short-circuits.

Related questions

Description : What is the advantage of HRC fuses when compared with rewireable fuses?

Last Answer : Ans.HRC fuses have high rupturing capacity, high speed of operation and no aging effect.

Last Answer : Protection by fuses is generally not used beyond 100 A .

Last Answer : The delay fuses are used for the protection of motors.

Description : The material used in liquid fuses is  (1) SF6 (3) carbon tetra chloride (2) distilled water (4) transformer oil

Last Answer : The material used in liquid fuses is  carbon tetra chloride

Last Answer : H.R.C. fuse, as compared to a rewirable fuse, has no ageing effect, high speed of operation, high rupturing capacity.

Description : ln HRC fuse the time between cut-off and final current zero is called

Last Answer : ln HRC fuse the time between cut-off and final current zero is called the arcing time

Description : H.R.C. fuses provide best protection against (a) overload (b) reverse current (c) open-circuits (d) short-circuits

Last Answer : (d) short-circuits

Description : what is HRC fuse?

Last Answer : HRC (High Rupturing Capacity) fuse HRC fuse is High Rupturing Capacity fuse. At the time of fault it disconnect the circuit very fast. Filling powder is silica sand. No flashover ... speed response Reliable No maintenance CheaperDisadvantages:- We have to replace it manually after each operation.

Description : Which type of protection is provided on a generator to protect against stator insulation failure? A) Differential protection B) Overcurrent relay C) Thermocouple actuated alarm D) Reverse power relay

Last Answer : Which type of protection is provided on a generator to protect against stator insulation failure? A) Differential protection B) Overcurrent relay C) Thermocouple actuated alarm D) Reverse power relay 

Description : A relay used for protection of motors against overload is :  (A) Impedance relay (B) Electromagnetic attraction type (C) Thermal relay (D) Buchholz's relay

Last Answer : D

Description : For protection of rotating machines against lightning surges _______ is used.  (1) lightning arrester (2) capacitor (3) combination of lightning arrester and capacitor (4) lightning conductor and arrester

Last Answer : For protection of rotating machines against lightning surges combination of lightning arrester and capacitor is used. 

Description : Reactance relay is normally preferred for protection against

Last Answer : Reactance relay is normally preferred for protection against earth faults

Description : Surge absorbers are used for protection against

Last Answer : Surge absorbers are used for protection against low voltage high frequency oscillations

Last Answer : A fuse in a motor circuit provides protection against short-circuit and overload.

Last Answer : The inverse definite mean time relays are used for over current and earth fault protection of transformer against internal short-circuits.

Last Answer : For the protection of power station buildings against direct strokes the requirements are interception, conduction and dissipation.

Last Answer : A thermal protection switch can protect against overload.

Description : Fuses placed in series with a thermal trip-type circuit breaker are used for _____________. A. time-delay protection B. short-circuit protection C. short duration surge protection D. sustained overload protection

Last Answer : Answer: B

Description : The delay fuses are used for the protection of ________ . (a) motors (b) power outlet circuits (c) fluorescent lamps (d) light circuits

Last Answer : (a) motors

Description : How long would the Suns initial supply of hydrogen last in both seconds and yrs as it fuses 600 bil. k ea. second total H avail. in its lifetime is 1.8x10 to 2nd pwr?

Last Answer : You are supposed to divide the total amount of hydrogen, by the consumption per second. That will give you the time in seconds. You can then convert that to years, by dividing by the number of seconds in a year.

Description : If the motor shown in the illustration will not start when 'Q' is depressed, which of the listed components should be checked FIRST? EL-0017 A. Fuses 'F-1' and 'F-2'. B. Operating coil 'C'. C. Contacts 'H-1', 'H-2', and 'H-3'. D. Contact 'H-4'.

Last Answer : Answer: A

Description : To check the three line fuses of a three-phase system consisting of a three-phase motor, you must _____________. A. place the starter in the 'stop' position B. make sure the motor is operating at full ... leads across the 'hot' ends of the fuses D. place the leads across the bottom ends of the fuses

Last Answer : Answer: A

Description : When replacing fuses, always make sure _______________. A. to stand on a rubber mat and use rubber gloves B. to use insulated pliers or screwdriver C. the fuse clips are straight, tight, and in good contact D. to increase the fuse rating 10% to guard against 'nuisance blowing'

Last Answer : Answer: C

Description : How does colostrum provide initial protection against diseases to newborn infants? Give one reason. -Biology

Last Answer : Colostrum contains necessary antibodies (IgA) that provide protection against diseases to newborn infants.

Description : How much protection does the PDP Nerf Armor provide against long falls?

Last Answer : I can't find anyone with anything bad to say about the PDP Nerf Armor.So it apparently does the job as well as you could expect.Someone would surely complain if it didn't.

Description : Sticky bands around tree trunks provide protection against

Last Answer : Ans. Mango mealy bug

Description : Explain the “Differential Protection Scheme” used for alternators with neat labeled diagram.

Last Answer : Differential Protection Scheme for Alternator: Figure shows the differential protection provided to 3 phase alternator. Here identical CTs are placed on both sides of 3 phase alternator and ... causing its operation. Relay sends trip signal to the CB, thereby alternator circuit is tripped.

Description : Explain with neat sketch, the Pilot wire protection scheme applied to transmission line.

Last Answer : Pilot Wire Protection scheme of Transmission Line : Figure shows the single line diagram of Merz price voltage balance system for pilot wire protection of three phase transmission line. ... through the relay, which gives trip signal to the circuit breaker for protection of transmission line.

Description : Explain differential protection scheme for busbars with neat sketch.

Last Answer : Differential Protection Scheme for Bus bar:  Under normal conditions, the sum of the currents entering the bus bar zone is equal to those leaving it and no current flows through the relay ... of these currents will flow through the relay coil causing opening of circuit breaker of bus-bar.

Description : Discuss in brief the principle of distance protection and state four advantages of distance protection scheme.

Last Answer : Advantages: 1. System is economical 2. High speed of interruption 3. Suitable for very long and high voltage transmission lines. 4. No problem of pilot wires.

Description : State two requirements of transmission line protection. 

Last Answer : Requirements of Transmission Line Protection: 1) Faults on lines should be quickly detected to initiate actions to maintain system stability. 2) For very long lines the protection system must be capable ... backup protection in the event of failure of circuit breaker (nearest to fault) to operate.

Description : List two limitations of Differential-Protection scheme for transformer.

Last Answer : Limitations of Differential Protection Scheme of Transformer:  1) Due to the magnetization characteristics of the CTs used, the ratio errors change with respect to the circulating currents.  2) ... & improper operation.  5) Inrush of magnetizing current may lead to inadvertent operation.

Description : Explain differential protection of busbar.

Last Answer : Differential protection Scheme for bus bar: Under normal conditions the sum of the currents entering the bus bar zone is equal to those leaving it and no current flows through the relay ... . The difference of these currents will flow through the relay coil causing opening of circuit breaker.

Description : Explain over-current protection of transformer.

Last Answer : Over-Current Protection of Transformer: Simple over-current & earth fault protection of transformer against external shortcircuit and excessive overloads is shown in the above figure. The ... trip command to the circuit breaker and the transformer is disconnected from load or fault.

Description : Explain negative phase sequence protection of alternator.

Last Answer : Negative phase sequence protection of alternator: Unbalanced loading on alternator mainly causes the negative sequence currents which generate the negative sequence components of magnetic fields. These fields ... components due to unbalance and operates the relay which further operates CB.

Description : Explain fault bus protection scheme.

Last Answer : Fault bus protection of busbar: In this scheme, the substation is so designed that every fault on the bus bar is converted to earth fault. Under normal operating conditions, there is no current flowing ... This results in operation of relay to actuate trip coil of CB to trip the circuit.

Description : Explain distance protection of transmission line with neat sketch diagram.

Last Answer : Distance protection of Transmission line: Distance protection scheme uses impedance relay. The relay operation is based on the impedance (or distance) between the relay and point of fault. Figure shows ... than ZL and impedance relay operates which operates the CB and line is protected.

Description : Write down limitation of differential protection of transformer.

Last Answer : Limitations of differential protection of transformer: 1) Due to the magnetization characteristics of the CTs used, the ratio errors change with respect to the circulating currents. 2) The pilot wires ... current (higher imbalance) due to which accuracy of sensing & operation is decreased. 

Description : How can we use CT and PT for protection purpose?

Last Answer : CT and PT for Protection purpose: Current transformer (CT) and Potential transformer (PT) are instrument transformers, which are used in conjunction with protective relays for protection purpose. The CT ... from the healthy part. In this way the CT and PT can be used for protection purpose.

Description : For complete protection of a three-phase line: A) three Phase relays and three Earth fault relays are required B) three Phase relays and two Earth fault relays are required C) two Phase relays and two Earth fault relays are required D) two Phase relays and one Earth fault relay are required

Last Answer : For complete protection of a three-phase line: two Phase relays and one Earth fault relay are required

Description :  For the protection of parallel feeders fed from one end, the relays used are: A) non-directional relays at the source-end and directional relays at the load-end B) non-directional relays at both the ... at the source-end and non-directional at the load-end D) directional relays at both the ends

Last Answer : For the protection of parallel feeders fed from one end, the relays used are: non-directional relays at the source-end and directional relays at the load-end

Description : A loss of excitation protection scheme for large generating unit employs A) under frequency relays B) offset Mho relay C) reactance relay D) percentage differential relay

Last Answer : A loss of excitation protection scheme for large generating unit employs offset Mho relay

Description : For complete protection ofa 3— phase line: (1) Three phase and three—earth fault relays are required (2) Three phase and two—earth fault relays are required (3) Two phase and two—earth fault relays are required (4) Two phase and one-earth fault relays are required

Last Answer : For complete protection ofa 3— phase line: Two phase and one-earth fault relays are required

Description : The type of backup protection scheme widely used in the field is (A) Relay backup (B) Breaker backup (C) Remote backup (D) Auxiliary backup

Last Answer : The type of backup protection scheme widely used in the field is Remote backup 

Description : Blind spot is a point in the zones of protection where

Last Answer : Blind spot is a point in the zones of protection where No protection is available.

Description : A negative sequence relay is used for protection of  (1) Generator (3) Motor (2) Transformer (4) Long Transmission lines

Last Answer : A negative sequence relay is used for protection of Generator 

Last Answer : Overfluxing protection is recommended for generator transformer of the power plant.

Last Answer : Over voltage protection is recommended for hydro-electric generators, steam turbine generators, gas turbine generators.

Last Answer : The single phasing relays are used for the protection of three phase motors.

Last Answer : Discrimination between main and back up protection is provided by the use of relays which are slow.