IDMT relays are used to protect the transformer against : External short circuits
Last Answer : The inverse definite mean time relays are used for over current and earth fault protection of transformer against internal 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 : The single phasing relays are used for the protection of three phase motors.
Last Answer : Impedance relays are used for phase faults on long line.
Description : A relay has a rating of 5 A, 2.2 sec IDMT and a relay setting of 125% TMS = 0.6. It is connected to a supply circuit through a C.T. 400/5 ratio. The fault current is 4000 A. The operating current of the relay is
Last Answer : A relay has a rating of 5 A, 2.2 sec IDMT and a relay setting of 125% TMS = 0.6. It is connected to a supply circuit through a C.T. 400/5 ratio. The fault current is 4000 A. The operating current of the relay is 6.25A
Last Answer : Thermal overload relays are used to protect the motor against overcurrent due to heavy loads.
Last Answer : To protect most of the electrical equipment handling low power, the types of relays used are thermocouple, electronic and bimetallic.
Last Answer : A thermal protection switch can protect against overload.
Last Answer : Discrimination between main and back up protection is provided by the use of relays which are slow.
Last Answer : Protective relays are devices that detect abnormal conditions in electrical circuits by measuring constantly the electrical quantities which differ during normal and abnormal conditions.
Last Answer : Directional relays are based on flow of power.
Description : D.C. shunt relays are made of?
Last Answer : D.C. shunt relays are made of many turns of thin wire.
Last Answer : Overload relays are of induction, solid state, thermal, electromagnetic type.
Last Answer : Relays can be designed to respond to changes in resistance, reactance or impedance voltage and current, light intensity, temperature.
Description : 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 : 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
Description : Consider the following statements. Which of these statements are correct ? (1) Reactance relays are preferred for ground fault relaying (2) Impedance relays are most suitable for:protecting long transmission lines (3) Mho relays are best ... (1) and (3) (C) (2) and (4) (D) (1), (2) and (4)
Last Answer : Consider the following statements. Which of these statements are correct ? (1) Reactance relays are preferred for ground fault relaying (2) Impedance relays are most suitable for:protecting long transmission lines (3) Mho relays are ... (1) and (3) (C) (2) and (4) (D) (1), (2) and (4)
Last Answer : Sandwich type winding is used in 3 phase shell-type transformer.
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 : 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 : Surge absorbers are used for protection against
Last Answer : Surge absorbers are used for protection against low voltage high frequency oscillations
Description : 45 The function of conservator in a transformer is A. To protect against internal fault B. To reduce copper as well as core losses C. To cool the transformer oil D. To take care of the expansion and contraction of transformer oil due to variation of temperature of surroundings
Last Answer : D. To take care of the expansion and contraction of transformer oil due to variation of temperature of surroundings
Description : Light triggering is mainly used in
Last Answer : Light triggering is mainly used in High voltage direct current transmission
Description : Earthing switch is used for? (A) Measuring of safety voltage (B) Protection of equipment from ground faults (C) Discharging residual energies (D) All of the above
Last Answer : Earthing switch is used for? (A) Measuring of safety voltage (B) Protection of equipment from ground faults (C) Discharging residual energies (D) All of the above
Description : Auto reclosing is used in case of
Last Answer : Auto reclosing is used in case of air blast C.B.
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
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
Description : Series reactors are used to
Last Answer : Series reactors are used to bring down the fault level within the capacity of the switchgear
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
Description : Regulating-transformers are used in power systems for control of
Last Answer : Regulating-transformers are used in power systems for control of power flow
Last Answer : A switchgear is device used for switching, controlling and protecting the electrical circuit and equipment.
Last Answer : The material used for fuse must have low melting point and high specific resistance.
Last Answer : Series capacitors are used to compensate for line inductive reactance.
Last Answer : The under voltage relay can be used for generators, busbars, transformers, motors.
Last Answer : A.C. network analyser is used to solve problems of load flow, short-circuit and stability.
Last Answer : Wave trap is used to trap waves of higher frequencies entering generator or transformer units.
Last Answer : Air blast circuit breaker is used for repeated duty.
Description : The operating point of a protective current transformer is near the
Last Answer : The operating point of a protective current transformer is near the Ankle point
Description : Which of the following is not a part of transformer installation? (A) Conservator (B) Breather (C) Buchholz Relay (D) Exciter
Last Answer : Which of the following is not a part of transformer installation? (A) Conservator (B) Breather (C) Buchholz Relay (D) Exciter
Description : The core construction is like spokes of a wheel in following transformer: (A) Berry Type Transformer (B) Core Type Transformer (C) Shell Type Transformer (D) None of the above
Last Answer : The core construction is like spokes of a wheel in following transformer: Berry Type Transformer
Description : The inrush current of a transformer at no load is maximum if the supply voltage is switched on (1) at peak voltage value (2) at zero voltage value (3) at half voltage value (4) at 0.866 time voltage value
Last Answer : At 0.866 time voltage value
Description : To prevent mal-operation of differentially connected relay while energizing a transformer, the relay restraining coil is based with (1) second harmonic current (2) third harmonic current (3) fifth harmonic current (4) seventh harmonic current
Last Answer : To prevent mal-operation of differentially connected relay while energizing a transformer, the relay restraining coil is based with second harmonic current
Last Answer : The short circuit in any winding of the transformer is the result of impulse voltage.
Description : What is the use of Buchholz relay in transformer?
Last Answer : This is a transformer that is used to step up and down current.
Description : Draw a typical time-current characteristic for IDMT relay.
Last Answer : Time-Current Characteristic for IDMT Relay:
Description : Select insulating materials for following parts : (i) Insulation between heating element and base plate of electric iron. (ii) Insulation used over copper or aluminium conductor used for making coils. (iii) Transformer bushings. (iv) Insulation between transmission line and pole.
Last Answer : Parts Insulating Materials Insulation between heating element and base plate of electric iron. Mica Insulation used over copper or aluminium conductor used for making coils. ... Transformer bushings Porcelain Insulation between transmission line and pole. Porcelain