With a neat sketch give the working of shaded pole induction motor.
Last Answer : Explanation: It has squirrel cage rotor and salient pole stator. The stator poles are shaded partially by short circuited conductor band to create the phase difference between the fluxes emerging from shaded ... rotating magnetic field in the air-gap and torque is exerted on the squirrel cage rotor.
Show More
269 views
2 answers
asked
Apr 27, 2020
by
anonymous

In the induction type directional over current relay, when a short-circuit occurs in the circuit (A) power flows in reverse direction (B) power flows in normal direction (C) directional power element does not operate (D) over current element is not energized
Last Answer : In the induction type directional over current relay, when a short-circuit occurs in the circuit power flows in reverse direction
Show More
124 views
1 answer
asked
Apr 28, 2018
by
anonymous

Last Answer : In a shaded pole single-phase motor, the revolving field is produced by the use of shading coils.
Show More
207 views
1 answer
asked
Mar 20, 2018
by
anonymous

State two applications of 1) Shaded pole motor 2) Universal motor
Last Answer : (i)Applications of Shaded pole motor: 1. Small fans 2. Toy motors 3. Hair dryers 4. Ventilators 5. Electric clocks 6. Record players 7. Motorized valves 8. Gramophones 9. Photocopying ... 5. Portable Drilling Machines 6. Electric Shavers 7. Mechanical computing Machines 8. Machine Tools etc.
Show More
125 views
1 answer
asked
Jul 26, 2019
by
anonymous

Last Answer : Locked rotor current of a shaded pole motor is slightly more than full load current.
Show More
85 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The shaded pole motor is used for low starting torque.
Show More
63 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In case of a shaded pole motor the direction of rotation of the motor is from main pole to shaded pole.
Show More
340 views
1 answer
asked
Mar 20, 2018
by
anonymous
.jpg)
Last Answer : A shaded pole motor can be used for toys, hair dryers, circulators etc.
Show More
103 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The range of efficiency for shaded pole motors is 5% to 35%.
Show More
120 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In a shaded pole motor, the shading coil usually consist of a single turn of heavy copper wire which is short-circuited and carries only induced current.
Show More
132 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Induction cup relay is operated due to changes in current, voltage, impedance.
Show More
352 views
1 answer
asked
Mar 20, 2018
by
anonymous

In a double squirrel cage induction motor, good starting torque is produced as (A) Large current flows through the outer high resistance winding. (B) Large current flows through the inner high ... the outer high resistance winding. (D) Large current flows through the inner low resistance winding.
Last Answer : In a double squirrel cage induction motor, good starting torque is produced as Large current flows through the outer high resistance winding.
Show More
137 views
1 answer
asked
May 8, 2018
by
anonymous

Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be
Last Answer : Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be 25 N -m
Show More
431 views
1 answer
asked
Apr 29, 2018
by
anonymous

The torque developed by any 3-phase induction motor at 0.8 p.u. slip is (A) Full-load torque (B) unstable torque (C) starting torque (D) break down
Last Answer : The torque developed by any 3-phase induction motor at 0.8 p.u. slip is unstable torque
Show More
3.1k views
1 answer
asked
Apr 28, 2018
by
anonymous

Last Answer : Speed torque characteristic of a repulsion induction motor is similar to that of a D.C. compound motor.
Show More
169 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Capacitor start motor has high torque in starting
Show More
136 views
1 answer
asked
Sep 13, 2017
by
anonymous

State the function and shape of following parts used in induction type energy meter: i) Series magnet ii) Shunt magnet iii) Al disc iv) Brake magnet
Last Answer : i) Series magnet: produce flux proportional to current (load current) of circuit and interact in the aluminum disc with flux produced by voltage magnet for torque production. Its shape is like letter U. ii) ... : brakes the motion of the aluminum disc or slows it down. Its shape is like letter C.
Show More
185 views
1 answer
asked
Sep 6, 2018
by
anonymous

Draw a neat sketch of 1-ph induction type energy meter and write operating principle of it.
Last Answer : Operating Principal:- The disc is placed between the two-flux due to pressure coil and flux due to current coil, which will set up torque on the disc which is proportional to power causing the ... is proportional to voltage, the second carries a current coil so its flux is proportional to current.
Show More
175 views
1 answer
asked
Sep 6, 2018
by
anonymous

List any four errors in induction type energy meter. Give method of compensation for each.
Last Answer : Errors in Induction Type Energy Meter with their Compensation: 1) Error due to friction: This error can be compensated by the additional shading band provided on the shunt electromagnet. 2) Phase ... error: This error can be compensated by providing a flux diverter' to the current magnet.
Show More
1.9k views
1 answer
asked
Sep 5, 2018
by
anonymous

An induction type energy meter is found to run fast. Correction for this error can be made by (A) Over-load compensation. (B) Voltage compensation. (C) Moving the brake magnet away from the centre of the disc. (D) Moving the brake magnet towards the centre of the disc.
Last Answer : An induction type energy meter is found to run fast. Correction for this error can be made by Moving the brake magnet away from the centre of the disc.
Show More
159 views
1 answer
asked
Apr 28, 2018
by
anonymous

Last Answer : Induction type single phase energy meters measure electric energy in kWh.
Show More
481 views
1 answer
asked
Mar 21, 2018
by
anonymous

The purpose of the restraining coil in a biased differential relay is (A) To reduce CT saturation during fault. (B) To increase the sensitivity of the relay. (C) To match the transformation ratio. (D) To limit the spill current through the relay during heavy external fault.
Last Answer : d
Show More
711 views
2 answers
asked
May 8, 2018
by
anonymous

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
Show More
550 views
2 answers
asked
May 8, 2018
by
anonymous
.jpg)
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
Show More
734 views
1 answer
asked
May 3, 2018
by
anonymous

The operating time of instantaneous relay is
Last Answer : The operating time of instantaneous relay is 0.1 sec
Show More
118 views
1 answer
asked
May 3, 2018
by
anonymous

What is the difference between relay and contactor?
Last Answer : Relay have smaller ratings. Contactor is a high rating relay.
Show More
5.1k views
1 answer
asked
May 2, 2018
by
anonymous

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
Show More
627 views
1 answer
asked
May 1, 2018
by
anonymous

Buchholz relay is (1) located in the conservator tank (2) located in the transformer tank itself (3) connected in the pipe connecting main tank of transformer and conservator (4) installed in the circuit breaker
Last Answer : Buchholz relay is connected in the pipe connecting main tank of transformer and conservator
Show More
119 views
1 answer
asked
Apr 30, 2018
by
anonymous

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
Show More
499 views
1 answer
asked
Apr 29, 2018
by
anonymous

Reactance relay is normally preferred for protection against
Last Answer : Reactance relay is normally preferred for protection against earth faults
Show More
121 views
1 answer
asked
Apr 29, 2018
by
anonymous

A solid state relay (A) withstands voltage transients (B) does not require auxiliary dc supply (C) provide low burden on CT and P (D) does not provide earth fault protection
Last Answer : A solid state relay provide low burden on CT and P
Show More
70 views
1 answer
asked
Apr 28, 2018
by
anonymous

Last Answer : Admittance relay is directional relay.
Show More
154 views
1 answer
asked
Mar 20, 2018
by
anonymous
.jpg)
Last Answer : The relay with inverse time characteristic will operate within 5 to 10 sec.
Show More
115 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The under voltage relay can be used for generators, busbars, transformers, motors.
Show More
68 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Reactance relay is preferred for phase fault on short transmission line.
Show More
110 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Interruption of large currents by relay requires arc suppressing blow out coils, wide separation of the opened contacts, high speed opening of contacts.
Show More
97 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Overheating of relay contacts or contact born out is due to slow making and breaking of load circuit contacts, foreign matter on the contact surface, too low contact pressure.
Show More
152 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : A differential relay measures the vector difference between two or more similar electrical quantities.
Show More
160 views
1 answer
asked
Mar 19, 2018
by
anonymous
.jpg)
Last Answer : Burden of a protective relay is the power absorbed by the circuit of relay.
Show More
811 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : In order that current should flow without causing excessive heating or voltage drop, the relay contacts should have low contact resistance, be clean and smooth, be of sufficient size and proper shape.
Show More
154 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : The relay operating speed depends upon the spring tension, the rate of flux built up, armature core air gap.
Show More
272 views
1 answer
asked
Mar 19, 2018
by
anonymous
.jpg)
How do relay works ?
Last Answer : Relay working like contact it is noise less
Show More
134 views
1 answer
asked
Dec 30, 2017
by
anonymous

What is the use of Buchholz relay in transformer?
Last Answer : This is a transformer that is used to step up and down current.
Show More
155 views
1 answer
asked
Dec 17, 2017
by
anonymous

What is the difference between a switch and a relay?
Last Answer : Switch is simply a mechanical contact mechanism and relay is a electromagnetic switch . Switch can be direct mechanically turn on and off but relay can be operated by energising coil .
Show More
111 views
1 answer
asked
Dec 17, 2017
by
anonymous

Describe IS – 95 forward link channel structure.
Last Answer : The IS-95 forward Channel structure consists of four types of logical Channels - pilot Channel, synchronization Channel, paging Channel, and forward traffic Channels. Each forward carrier Channel contains one ... . This code is known as the channel identifier. This code is different for each user
Show More
90 views
1 answer
asked
Aug 6, 2019
by
anonymous

Justify the statements. 1. IGBT uses a vertically oriented structure. 2. IGBT is preferred as a power switch over both power BJT and MOSFET. 3. Punch through IGBT structure are more popular and are widely used.
Last Answer : 1. IGBT uses vertically oriented structure. IGBT use vertically oriented structure to reduce the resistance and to increase the current flow area. Hence IGBT uses vertically oriented ... DC circuit applications. Hence punch through IGBT structure are more popular and are widely used.
Show More
3.0k views
1 answer
asked
Sep 15, 2017
by
anonymous

EPROM internal structure
Last Answer : EPROM (Erasable Programmable ROM): EPROM stands for Erasable Programmable ROM.Data is stored in EPROM memory cell as an electrostatic charge on highly insulated conductor. The charge can remain for ... figure shows EPROM memory cell consisting of a single NMOS filed effect transistor.
Show More
1.2k views
2 answers
asked
Aug 3, 2017
by
anonymous


A 3-phase, 4-pole, 50Hz induction motor runs at a speed of 1440 rpm. The rotating field produced by the rotor rotates at a speed of ________ rpm with respect to stator field. (A) 1500 (B) 0 (C) 1440 (D) 60
Last Answer : 0
Show More
2.1k views
2 answers
asked
Apr 28, 2018
by
anonymous
.jpg)
The torque produced in wattmeter is proportional to
Last Answer : A
Show More
1.2k views
2 answers
asked
Apr 26, 2018
by
anonymous
