Power System Protection MCQ Part 7. Air free from moisture c. Air should have least CO 2 d. Air must have oil mist. An arc chute for an electric circuit breaker comprises insulating sidewalls and plates, or fins, of insulating material that extend transversely of the sidewalls and have edges for engaging the arc as it moves into the chute. Arc interruption is an important part of the use of industrial circuit breakers for both the safety of those who work in a facility as well as the facility itself. View Answer / Hide Answer A common arc control scheme used in many circuit breaker designs, (i.e. The arcing contacts in a circuit breaker are made of (a) copper tungsten alloy (b) porcelain (c) electrolytic copper (d) aluminium alloy. Part of circuit breaker helpful in breaking the current is. The arc chute actually looks somewhat like this It is a box with several plates placed at fixed distance. 5. Actually the configuration of the arcing contacts creates the Jacobs ladder effect, then the chutes take over. Arc chutes use arc runners to draw t... Equal to 1. c. Less than 1. d. A negative value. The functioning depends on what kind of chute and current it is. The sidewalls and edges of the plates are coated with a plasma-arc-sprayed refractory metal-oxide consisting essentially of amorphous fused silica. The circuit breaker which uses more oil or which is bulky is called bulk oil circuit breaker. Ans: d. 18. a. The arc is made to drive in it. The arc is magnetically blown into arc chutes where the arc is lengthened, cooled, and extinguished. Porcelain. These coils are called blowout coils because they help blow out the arc magnetically. D. None of the above. Arc in a circuit breaker is interrupted at. Breaking capacity of a circuit breaker rated 1000 A, 1000 MVA, 33 kV is: 1000 A; 1783 A; 1783 MVA; 1000 MVA The arc voltage produced in the circuit breaker is always. You have already completed the quiz before. MCQ on Switchgear and Protection – 4. 19) Assertion (A): In comparison to making capacity of a circuit breaker its breaking capacity is normally higher. a. 3 The fluids used in circuit breaker should be. We can use fuse protection for current rating up to: (A) 50 A (B) 100 A (C) 20 A (D) 10 A. These types of air circuit breaker were used for the system voltage of 245 KV, 420 KV and even more, especially where faster breaker operation was required. Ans: (a) 19. See Fig. Reason (R): The breaking capacity of a CB is expressed as √3 * VI * 10-6 MVA. An arc chute is generally comprised of a pair of slightly spaced walls of heat resistant, electrically insulating material that confine and extinguish an arc by cooling the arc to extinguishing temperatures. Without arc chutes, the breaker contacts would need to be a lot larger and … Main purpose of oil in oil circuit breaker is to A. We should invent a kids game related to our industry, Arc Chutes and Jacob's Ladders. 4. c. Short circuit. a method used to increase the total arc voltage across the main contacts), is to force the arc into an arc baffle or splitter structure. Both A and R are true and R is the correct explanation of A. b. Overload . The arcing contacts in a circuit breaker are made of. Thank you all for the pointers. To reduce short circuit fault currents are used. May 22, 2017 by admin. These are : potential difference between the contacts. You have to finish following quiz, to start this quiz: Results. The arc chute will help in achieving cooling. 0 of 12 questions answered correctly. Get latest price. For total interruption of current the circuit breaker it is essential to quench the arc as quickly as possible. The main designing criteria of a circuit breaker is to provide appropriate technology of arc quenching in circuit breaker to fulfill quick and safe current interruption. Principles and Methods of arc extinction are discussed here. Construction of an air circuit breaker (arc-chute type) used for low and medium voltage is shown in the Figure. 40. The arc chute is a series of plates in the path of that arc that split it up into smaller segments, lowering the energy in each arc segment to where it need less dielectric strength (of air) to extinguish it, or really, to not allow it to sustain itself any longer. d) Arc chamber is broken. d. Over voltage View Answer / Hide Answer. Which type of air is used in air blast circuit breaker? (B) maximum current. (c) protect the appliance. Design details are given for the coil-less cold-cathode arc-chute circuit breaker, illustrating the fundamental requirements of the arc chute, contacts, mechanism and withdrawable circuit breaker in its metal enclosed cubicle for use up to 3 kV dc. Ans:--b. Answer: (a) in phase with arc current. (A) Water (B) Air (C) SF6 gas (D) Vacuum. A thermal protection switch provides protection against what? Electrical Engineering MCQ [ hide] 1 Mho relay is. For a DC arc, there are blow magnets that force the arc from the contacts into... (e) none of the above. It is also known by other names such as arc dividers or arc splitters. The number of plates in the arc chute is dependent on the short-circuit rating and nominal voltage of the circuit breaker. In larger ratings, oil circuit breakers rely upon vaporization of some of the oil to blast a jet of oil through the arc. D. Linear resistors are used in resistance switching. Which material is used for making acting contacts for circuit breakers? When the breaker interrupts the fault current an arc is generated between the contacts of the breaker. a. Answer/ Hint In a circuit breaker contact wipe is necessary. 2 At the instant of contact separation in circuit breaker the current which exists is given the name. (a) protect the line. 1. Air blast circuit breaker has some specific advantages over oil circuit breaker which are listed as follows,. The chamber is known as “arc chute”. The voltage that appears across the contact of circuit breaker during arcing periods is called Arc voltage. Power System Protection. A.C. air break circuit breakers are used for. 3. Temperature. The breaking action becomes more effective with heavy currents. The construction is simple and it consists of fixed and moving contacts enclosed in a strong weather – tight earthed tank containing oil up to a certain level and an air cushion above the oil level. This is training video . Low voltage circuit breakers have rated voltage of less than 220 V 400V 1000 V 10,000 V 3. Arc chute is a set of parallel arranged metal plates which extinguishes the arc formed when the circuit breaker interrupts the high electric current. It is also known by other names such as arc dividers or arc splitters. It is an important component of the circuit breaker. These metal plates have an equal air gap between them. The circuit breakers which produces the least arc energy. 17.Air blast circuit breaker is used for (a) over currents (b) short duty (c) intermittant duty (d) repeated duty. Electric arc produces … The main contacts are usually made of copper and carry the current in the closed position of the circuit breaker. These metal plates have an equal air gap between them. 1.Ionization in circuit breakers is facilitated by. There are two sets of contacts in such breakers named as main contacts and arcing contacts. These circuit breakers contain so-called arc chutes, a stack of mutually … ACB for example a Miniature Circuit Breaker (MCB). Arc chutes principles in air at LV circuit breaker Photo source from Switching in Electrical Transmission and Distribution Systems book (figure 6.6 page 170) The primary functions of the arc chutes are: arc motion, elongation, and cooling by convection. Outfitted with a latest infrastructure, we have been able to manufacture and supply a wide array of MCB ARC Chute. (c) load flow and stability. Hence you can not start it again. Answer: (c) inserting a capacitor in parallel with the contacts. A.C. network analyser is used to solve problems of. More B No.125, 2nd Main Road Chamraj Pet, Bengaluru, Karnataka, India. This breaker makes use of oil for quenching the arc. Online MCQ EE-Circuit Breakers Part Three. 31. B. Energizing of the trip circuit and the arc extinction on an opening operation. The current zero interruption, in oil and air blast circuit breakers, is achieved by b) Voltage rises. a) Arc is produced. Electrolytic … Oil circuit breakers are the oldest type of circuit breakers which used oil as a dielectric or insulating medium for arc extinction. Applications of Circuit Breakers - MCQs with answers Q1. Arc chutes can be found inside circuit breakers, contactors, isolators and other high current interruption devices. Air Blast Circuit Breaker - MCQs with answers Q1.