A circuit breaker is designed to protect an electrical circuit from damage caused by :
(A) Over load (B) Short circuit (C) Over current (D) All of the above
Last Answer : Air blast circuit breakers for 400 kV power system are designed to operate in 50 millisecond.
Description : The arc temperature in Oil Circuit Breaker may reach up to_______. (A) 5,000° K (B) 8,000° K (C) 10,000° K (D) None of the above
Last Answer : The arc temperature in Oil Circuit Breaker may reach up to 5,000° K
Description : The number of cycles in which a high speed circuit breaker can complete its operation is (A) 3 to 8 (B) 10 to 18 (C) 20 to 30 (D) 40 to 50
Last Answer : The number of cycles in which a high speed circuit breaker can complete its operation is 3 to 8
Description : The Minimum Oil Circuit Breaker (MOCB) is named because of : (A) Reduced requirement of oil (B) Reduced requirement of air (C) All of the above (D) None of the above
Last Answer : The Minimum Oil Circuit Breaker (MOCB) is named because of : Reduced requirement of oil
Description : For selecting a circuit breaker, ______ should be determined. (A) initial current that flows on occurrence of a short circuit only (B) transient current that flows at the time of circuit interruption only (C) resonant frequency only (D) (A) and (B)
Last Answer : For selecting a circuit breaker, ______ should be determined. (A) initial current that flows on occurrence of a short circuit only (B) transient current that flows at the time of circuit interruption only (C) resonant frequency only (D) (A) and (B)
Description : ln a minimum oil circuit breaker the oil is used
Last Answer : ln a minimum oil circuit breaker the oil is used to act as circuit breaking medium only
Last Answer : Arc in a circuit breaker is interrupted at zero current.
Last Answer : The arc voltage produced in A.C. circuit breaker is always in phase with the arc current.
Last Answer : In a circuit breaker the basic problem is to transmit large power.
Last Answer : Ionization in circuit breaker is facilitated by high temperature, increase of mean free path, increasing field strength.
Last Answer : The voltage appearing across the contacts after opening of the circuit breaker is called recovery voltage.
Last Answer : Air blast circuit breaker is used for repeated duty.
Last Answer : Magnetic circuit breaker has instantaneous trip action.
Last Answer : Thermal circuit breaker has delayed trip action.
Last Answer : The arcing contacts in a circuit breaker are made of copper tungsten alloy.
Description : what is SF6 circuit breaker?
Last Answer : SF6 is Sulpher hexa Fluoride gas. If this gas is used as arc quenching medium in a Circuit breaker means SF6 CB.
Description : Explain about Circuit Breaker
Last Answer : Ans: CIRCUIT BREAKERS: In the case of outdoor type installation, the circuit breakers have fixed location and the station layout is such that adequate section clearances are always available from ... carried out as above, every circuit breaker will be completely overhauled after five year interval.
Description : How to Reset a Circuit Breaker
Last Answer : How to Reset a Circuit Breaker All is well with the lights and your electrical appliances one minute, then everything falls into pitch-black darkness the next moment. When a room in your house ... electrical fires. With these tips, a power surge does not have to be a permanent inconvenience.
Description : How to Install a Circuit Breaker
Last Answer : How to Install a Circuit Breaker A circuit breaker is an essential component of a home's electric system. When power surges occur, it trips then shuts off the electricity, preventing ... -functional electrical system. Just make sure you take proper safety precautions when installing this device.
Description : Explain working of static AC circuit breaker.
Last Answer : Static AC Circuit breaker: The circuit configuration of static AC circuit breaker using SCR is shown in the figure. When switch S' is closed, the SCRs T1 and T2 are fired in positive ... non-availability of gate current. Thus the maximum time delay for breaking the circuit is one half-cycle.
Description : Explain working of AC circuit breaker using SCR with circuit diagram.
Last Answer : AC Circuit Breaker: The circuit configuration of static AC circuit breaker using SCR is shown in the figure. When switch S' is closed, the SCRs T1 and T2 are fired in positive ... to non-availability of gate current. Thus the maximum time delay for breaking the circuit is one half-cycle.
Description : State function of starter and ELCB. (Earth Leakage Circuit Breaker)
Last Answer : i) Function of Starter:- 1. To prevent the high starting current OR to minimize the starting current. 2. To give supply failure protection 3. To give over load and short circuit protection ... an installation and cut off the circuit from power supply and avoid electrical shock to the person.
Description : Breaking capacity of a circuit breaker is usually expressed in terms of (1) Ampere (2) Volts (3) MW (4) MVA
Last Answer : Breaking capacity of a circuit breaker is usually expressed in terms of MVA
Description : The arc voltage in a circuit breaker is :
Last Answer : The arc voltage in a circuit breaker is : in phase with the arc current
Description : Which of the following is used in a circuit breaker as the medium in which the arc forms? A) Insulating gas B) Insulating oil C) Vacuum D) All the above
Last Answer : Which of the following is used in a circuit breaker as the medium in which the arc forms? A) Insulating gas B) Insulating oil C) Vacuum D) All the above
Description : IDMT relays are used to protect the transformer against : (A) Internal short -circuits (B) Open circuits (C) External short circuits (D) Oil leakage
Last Answer : IDMT relays are used to protect the transformer against : External short circuits
Description : To protect the power transformer (Y-Y with neutral grounded) against fault, what type of connection do the CTs have ?
Last Answer : To protect the power transformer (Y-Y with neutral grounded) against fault, what type of connection do the CTs have ? Δ-Δ connection
Last Answer : A thermal protection switch can protect against overload.
Last Answer : An efficient and a well designed protective relaying should have good selectivity and reliability, economy and simplicity, high speed and selectivity.
Last Answer : Relays can be designed to respond to changes in resistance, reactance or impedance voltage and current, light intensity, temperature.
Description : What is electrical circuit ?
Last Answer : An electric circuit is the interconnection of electrical elements. Electrical elements like battery, lamp, wire etc.
Description : An electrical circuit with 10 branches and 7 junctions will have
Last Answer : An electrical circuit with 10 branches and 7 junctions will have 4 loop equations.
Description : The resistance of a few meters of wire conductor in closed electrical circuit is?
Last Answer : The resistance of a few meters of wire conductor in closed electrical circuit is practically zero.
Description : Power factor of an electrical circuit is equal to?
Last Answer : Power factor of an electrical circuit is equal to R/Z, cosine of phase angle difference between current and voltage, kW/kVA.
Description : What is a node in an electrical circuit?
Last Answer : a positively charged electrons
Description : How to Protect Yourself from Swine Flu
Last Answer : How to Protect Yourself from Swine Flu Swine flu, which is also called H1N1 is a respiratory infection caused by a strain of influenza virus. This disease affected millions of people ... to prevent the transmission of microorganisms would also help in preventing you from acquiring this illness.
Description : How to Protect Outdoor Furniture
Last Answer : How to Protect Outdoor Furniture Outdoor furniture are made sturdy, so they can last under the harsh conditions presented by your home's outdoor environment. However, without additional protection, the ... in fact, they will make your property look tacky. So better do the necessary cleaning.
Description : How to Protect Leather
Last Answer : How to Protect Leather Genuine leather is a beautiful material that can last years when taken care of properly. Here's how to protect your investment and enjoy your leather for years to come. ... days before using the leather item once again. Keep your leather protected from humidity and dampness.
Description : How to Password Protect a File ?
Last Answer : How to Password Protect a File We all have secure computer files we want to protect from unwanted and unauthorized access. One of the lines of defense for securing files is a safe and secure ... , you can protect your files from unauthorized access and maintain a very safe, secure computer system.
Description : How to Protect Your Passwords ?
Last Answer : How to Protect Your Passwords Passwords are the first line of security for many end-users. Whether it's for e-mail, an online shopping service, or a social networking site, ... confidently access your personal accounts without having to worry about other people stealing your personal information.
Description : An inductor is connected in series with SCR to protect it from A) Excessive high voltage B) Excessive high dv/dt C) Excessive high di/dt D) Excessive large forward current
Last Answer : An inductor is connected in series with SCR to protect it from Excessive high di/dt
Description : Explain the lighting scheme to be designed for each of the following: i) Special ward in hospitals ii) Dentist’s Cabin
Last Answer : i) Special ward in hospital: For the patients in the wards, lighting should create a cozy and pleasant atmosphere. Lighting in the wards should be planned in such a way that it meets the specific ... we use such as cements and bonding agents that we use to restore your teeth back to health.
Description : What would happen if a power transformer designed for operation on 50 Hz (frequency) were connected to a 500 Hz (frequency) source of the same voltage: (A) Eddy Current and Hysteresis losses will be ... Current will be too much high (C) Transformer may start to smoke and burn (D) No effect
Last Answer : What would happen if a power transformer designed for operation on 50 Hz (frequency) were connected to a 500 Hz (frequency) source of the same voltage: (A) Eddy Current and Hysteresis losses will be ... will be too much high (C) Transformer may start to smoke and burn (D) No effect
Last Answer : D.C. generators are normally designed for maximum efficiency around full-load.
Last Answer : The efficiency of a properly designed synchronous motor will usually fall in range 85 to 95%.
Last Answer : Generators for peak load plants are usually designed for maximum efficiency at 50 to 75 percent full load.
Last Answer : Overhead system can be designed for operation up to 400 kV.
Description : Briefly explain how the power factor of an inductive circuit can be improved.
Last Answer : As we know that power factor should be corrected to ensure that the current supplied is cost friendly. Meaning the power factor should be around one but not greater than one(0.8-0.9) in a ... an inductive circuit due to the inductive reactance which oppose the change of current in the ac circuit.
Description : If the % reactance upto the fault point is 20%, then the short circuit current will be
Last Answer : If the % reactance upto the fault point is 20%, then the short circuit current will be 5 times the full load current
Description : Which of the following circuit breakers has high reliability & minimum maintenance? (A) Bulk oil type CB (B) Air blast CB (C) Vacuum CB (D) Sulphur hexafluoride CB
Last Answer : Which of the following circuit breakers has high reliability & minimum maintenance? (A) Bulk oil type CB (B) Air blast CB (C) Vacuum CB (D) Sulphur hexafluoride CB