Which of the following electric meter movements uses a stationary permanent magnet and movable coil? A. D'Arsonval B. Electrodynamometer  C. Moving iron-vane D. Inclined coil iron-vane

1 Answer

Answer :

Answer: A

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Description : A useful instrument for checking A.C. motor performance by measuring possible unbalanced currents is the _____________. A. hand or battery-operated megger B. vibrating-reed frequency meter C. hook-on voltmeter-ammeter D. D'Arsonval iron-vane probe

Last Answer : Answer: C

Description : What is the primary advantage of the electrodynamometer type meter over the D’Arsonval-type meter?

Last Answer : The electrodynamometer-type meter can be used to measure both ac and dc currents.

Description : What is the primary advantage of the electrodynamometer type meter over the D’Arsonval-type meter?

Last Answer : The electrodynamometer-type meter can be used to measure both ac and dc currents.

Last Answer : A moving-coil permanent-magnet instrument can be used as flux-meter by eliminating the control springs.

Description : Give reason: Stationary coil and stationary magnet cannot produce induced electric current.

Last Answer : An emf is induced in the coil only when there is relative motion between the coil and the magnet.

Description : What is the effect of current flow through the coil in a d’Arsonval meter movement?

Last Answer : A magnetic field is generated around the coil and the attraction of this field with the permanent magnet causes the coil to move

Description : What component supplies restoring force to the coil of the D’Arsonval meter movement?

Last Answer : Hairspring.

Description : What component of the D’Arsonval meter movement completes the circuit for current flow to the coil?

Last Answer : Hairspring.

Description : Permanent-magnet moving coil instrument can be used in

Last Answer : dc work only

Description : What is the reason why the scale of a permanent-magnet moving coil instrument is uniform?

Last Answer : because it is spring controlled

Description : Permanent Magnet Moving Coil (PMMC) Instrument

Last Answer : Permanent Magnet Moving Coil (PMMC) Instrument

Description : A permanent magnet moving coil instrument gives full scale deflection of 25mA when a voltage of 75mV is applied across it. Calculate: (i) Resistance of shunt required for full scale deflection of 150 A. (ii) Series resistance for full scale deflection of 500 V.

Last Answer : Answer :

Description : Name the material used for :- (i) Moving coil (ii) Permanent magnet in PMMC instrument.

Last Answer : (i) Material used for Moving coil: Copper, Aluminum( some times)  (ii) Permanent magnets are made of special alloys such as :  Aluminum-Nickel-Cobalt (Alnicos)  Strontium-Iron  Neodymium-Iron-Boron  Samarium-Cobalt.

Description : A permanent magnet moving coil ammeter has a coil resistance of 99 ohm and Full Scale Deflection (FSD) current of 0.1mA. Shunt resistance is 1 ohm. Current through the meter at 0.5 F.S.D is:

Last Answer : A permanent magnet moving coil ammeter has a coil resistance of 99 ohm and Full Scale Deflection (FSD) current of 0.1mA. Shunt resistance is 1 ohm. Current through the meter at 0.5 F.S.D is: 0.05mA

Description : Permanent magnet moving coil instruments are used for

Last Answer : PMME are mostly used for measuring voltage and current.

Description :  The main sources of Errors in Permanent Magnet moving Coil (PMMC) are due to : - a) weaking of the permanent magnet due to aging at temperature effects b) weaking of spring due to aging and temperature effects c) change of resistance of the moving coil with temperature d) all the above

Last Answer :  The main sources of Errors in Permanent Magnet moving Coil (PMMC) are due to : - a) weaking of the permanent magnet due to aging at temperature effects b) weaking of spring due to aging and temperature effects c) change of resistance of the moving coil with temperature d) all the above

Last Answer : A moving-coil permanent-magnet instrument can be used as ammeter by using a low resistance shunt.

Description : The working of a meter is based on the use of a permanent magnet. In order to protect the meter functioning from stray magnetic fields (a) meter is surrounded by strong magnetic fields (b) a soft ... is used (c) a plastic shielding is provided (d) a shielding of anon-magnetic material is used

Last Answer : (b) a soft iron shielding is used

Description : Can a static magnet induce an e.m.f in a stationary coil of wire? Give reasons.

Last Answer : No, when both coil and magnet are stationary, the magnetic field linked with the coil remains constant. Only when the magnetic field linked with the coil changes, current is produced.

Description : The true power indicated by a wattmeter depends on the current flow through the load, the magnitude of the potential across the load, and the _____________. A. power factor of the load B. angle of coil displacement C. inertia of the movable coil D. high resistance from the load

Last Answer : Answer: A

Description : The true power indicated by the pointer movement of a wattmeter depends on the current flow through the load, the magnitude of the potential across the load, and the ____________. A. power factor of the ... B. angle of coil displacement C. inertia of the movable coil D. high resistance from the load

Last Answer : Answer: A

Description : Permanent magnet is normally made of- (a) Aluminum (b) Wrought iron (c) Cast iron (d) Alnico alloys

Last Answer : Ans: C

Description : Explain the error occurred due to pressure coil inductance of electrodynamometer type wattmeter. How this error is compensated?

Last Answer : For power measurement assume that the pressure coil of wattmeter is purely restitive. Hence current taken by pressure coil Ipc is in phase with voltage across the pressure coil Vpc  ... inductive reactance XL the pressure coil circuit is made purely resistive and the error is eliminated.

Description : For attaining maximum efficiency, a Francis turbine runner is so designed as to result in radial discharge at exit. This is done by : a) Providing runner vane angle at inlet as 90o b) Providing ... 90o d) Designing for absolute velocity at outlet to be inclined at 90o to direction of vane there

Last Answer : d) Designing for absolute velocity at outlet to be inclined at 90o to direction of vane there

Description : Which one of the following statements is not correct ? (a) A surveyor's compass has two sight vanes (b) A prismatic compass has an object vane and an eye vane (c) A trough compass ... table (d) In a prismatic compass the graduations on the aluminimum disc rotate and the index remains stationary

Last Answer : (a) A surveyor’s compass has two sight vanes

Description : Magnetic flux linked with a coil can be changed by using an: a. Permanent magnet b.Bar magnet c. Electromagnet d. Horseshoe magnet

Last Answer : b.Bar magne

Last Answer : The series magnet of a single phase Energy meter consists of coil of thick wire of few turns.

Description : What is the limiting factor as to the amount of current an electrodynamometer meter movement can handle?

Last Answer : Size of spiral conducting.

Description : What components in an electrodynamometer-type meter movement produce the magnetic field?

Last Answer : Fixed coils.

Description : What is the limiting factor as to the amount of current an electrodynamometer meter movement can handle?

Last Answer : Size of spiral conducting.

Description : What components in an electrodynamometer-type meter movement produce the magnetic field?

Last Answer : Fixed coils.

Description : The working of a meter is based on the use of a permanent magnet. In order to protect the meter functioning from stray magnetic fields

Last Answer : The working of a meter is based on the use of a permanent magnet. In order to protect the meter functioning from stray magnetic fields a soft iron shielding is used.

Description : In a stationary wave, nodes are at A. fixed points B. movable points C. there are no nodes D. random points

Last Answer : fixed points

Description : An indicating instrument whose movable coils rotate between two-stationary coils, usually used as wattmeter

Last Answer : electrodynamometer

Description : The pole faces of U-shaped magnet in a moving coil galvanometer are made concave to a) decrease the strength of magnetic field b) create a non-uniform magnetic field c) make the magnetic field radial d) All of these

Last Answer : c) make the magnetic field radial

Description : How can a d’Arsonval meter movement be adapted for use as an ac meter?

Last Answer : By the use of a rectifier

Description : What are three functions of the hairsprings in a d’Arsonval meter movement?

Last Answer : To return the pointer to its rest position when there is no current flow; to oppose the coil movement when there is current flow; to provide electrical connections for the coil.

Description : What type of meter movement is the d’Arsonval meter movement?

Last Answer : A permanent-magnet moving-coil meter movement used in most electrical and electronic meters.

Description : What modification is made to the D’Arsonval meter movement to enable the meter to measure voltage?

Last Answer : A multimeter (high resistance) is placed in series with the coil of the meter.

Description : What advantage is gained by using pole pieces with curved faces in the D’Arsonval meter movement?

Last Answer : Two-position and three-position.

Description : Electric strip heaters are used in motor controllers to _____________. A. prevent freezing of movable contacts B. keep the components at their design ambient temperature C. prevent condensation of moisture D. minimize resistance in internal circuits

Last Answer : Answer: C

Description : How can electric currents be induced with a coil and a magnet?

Last Answer : by moving either the magnet or the coil

Description : Vane anemometer (A) Is an area meter (B) Is a variable head meter (C) Rotates an element at a speed determined by the velocity of the fluid inwhich the meter is immersed (D) None of these

Last Answer : (C) Rotates an element at a speed determined by the velocity of the fluid inwhich the meter is immersed

Description : Magnetic field can be produced by using A. permanent magnet B. electric current C. temporary magnet D. both A and B

Last Answer : permanent magnet

Description : In motor a permanent magnet provides: a. Electric field b. electric flux c. magnetic field d. gravitational field

Last Answer : d. gravitational field

Description : The timer element of a reverse power relay cannot be energized unless _____________. A. the power flow is the same as the tripping direction B. the power flow is the opposite to the tripping direction C. the movement of the disk is damped by a permanent magnet D. one generator is motorized

Last Answer : Answer: A

Description : The timer element of a reverse power relay cannot be energized unless _____________. A. one generator is fully motorized B. the movement of the disk is damped by a permanent magnet C. the power flow is the same as the tripping direction D. the power flow is the opposite to the tripping direction

Last Answer : Answer: C

Description : Which of the following iron and steel is used to make a permanent magnet ?

Last Answer : Steel is used between cast iron and steel to make permanent magnets.

Description : When a piece of iron rod is brought near a permanent magnet for a while it becomes magnitised by?

Last Answer : Need answer

Description : The most suitable metal for making permanent magnet is a) Iron b) Steel c) Silver d) Copper

Last Answer : a) Iron