Which of the following instruments have least torque/weight ratio: a) Dynamometer type b) PMMC c) Attraction type moving iron d) Repulsion type moving iron

Which of the following instruments have least torque/weight ratio: a) Dynamometer type b) PMMC c) Attraction type moving iron d) Repulsion type moving iron
by

1 Answer

Answer :

Ans: A
by
selected by

Related questions

Moving iron and PMMC instruments can be distinguished from each other by looking at:

Last Answer : Moving iron and PMMC instruments can be distinguished from each other by looking at: Scale

Attraction and repulsion instruments are considered

Description : Attraction and repulsion instruments are considered

Last Answer : moving iron instruments

In the case of PMMC rectifier type instruments, the deflecting torque is proportional to

Last Answer : In the case of PMMC rectifier type instruments, the deflecting torque is proportional to Average value of AC current.

Dynamometer type moving coil instruments are provided with _____.

Last Answer : Dynamometer type moving coil instruments are provided with pneumatic damping

State the material used for moving coil and former for PMMC instruments.

Description : State the material used for moving coil and former for PMMC instruments. 

Last Answer : Material Used for Moving Coil and Former for PMMC Instruments:  Material used for moving coil: Copper  Material used for Former: Aluminium

A transformer works on the basic principle of ____________. A. self impedance B. attraction and repulsion C. mutual induction D. increasing power

Description : A transformer works on the basic principle of ____________. A. self impedance B. attraction and repulsion C. mutual induction D. increasing power

Last Answer : Answer: C

The rotor slots of a repulsion-type motor are generally skewed (placed nonparallel to the rotor axis) to _________. A. produce a constant starting torque B. permit a greater air gap with the starter C. permit a smaller air gap with the starter D. reduce eddy current losses

Description : The rotor slots of a repulsion-type motor are generally skewed (placed nonparallel to the rotor axis) to _________. A. produce a constant starting torque B. permit a greater air gap with the starter C. permit a smaller air gap with the starter D. reduce eddy current losses

Last Answer : Answer: A

Which of the instruments listed is used to check insulation resistance? A. Magneto B. Megohmmeter C. Dynamometer D. Rheostat

Description : Which of the instruments listed is used to check insulation resistance? A. Magneto B. Megohmmeter C. Dynamometer D. Rheostat

Last Answer : Answer: B

Which of the following is a characteristic of fractional horsepower repulsion start motors? A. They start with a rotating stator field. B. The short circuiting ring is removed from the commutator while starting. C. The brushes are removed from the commutator while starting. D. They have a low starting torque.

Description : Which of the following is a characteristic of fractional horsepower repulsion start motors? A. They start with a rotating stator field. B. The short circuiting ring is removed from the commutator while ... brushes are removed from the commutator while starting. D. They have a low starting torque.

Last Answer : Answer: B

Why do we use capacitor-start induction motors in applications requiring high starting torque in preference to repulsion induction motors?

Description : Why do we use capacitor-start induction motors in applications requiring high starting torque in preference to repulsion induction motors?

Last Answer : Capacitors are easily available, cheaper and reliable. Repulsion-induction motors posses a special commutator and brushes that require maintenance. Most manufacturers have stopped making them.

Why do we use capacitor-start induction motors in applications requiring high starting torque in preference to repulsion induction motors?

Description : Why do we use capacitor-start induction motors in applications requiring high starting torque in preference to repulsion induction motors?

Last Answer : Ans : Capacitors are easily available, cheaper and reliable. Repulsion-induction motors posses a special commutator and brushes that require maintenance. Most manufacturers have stopped making them.

Explain with neat sketch; the construction and working principle of Repulsion type moving iron instrument.

Description : Explain with neat sketch; the construction and working principle of Repulsion type moving iron instrument.

Last Answer : Repulsion Type Moving Iron Instrument: Construction: It consist of fixed cylinder hollow coil which carries operating current inside the coil there are two soft iron pieces. One of which is ... magnetized with same polarity a repulsive force act on them and moving iron piece gets deflected. 

During the formation of a chemical bond - (1) energy decreases (2) energy increases (3) energy of the system does not change (4) electron-electron repulsion becomes more than the nucleus-electron attraction

Description : During the formation of a chemical bond - (1) energy decreases (2) energy increases (3) energy of the system does not change (4) electron-electron repulsion becomes more than the nucleus-electron attraction

Last Answer : (1) energy decreases

Temperature of a gas is produced due to  (a) its heating value  (b) kinetic energy of molecules  (c) repulsion of molecules  (d) attraction of molecules  (e) surface tension of molecules.

Description : Temperature of a gas is produced due to  (a) its heating value  (b) kinetic energy of molecules  (c) repulsion of molecules  (d) attraction of molecules  (e) surface tension of molecules.

Last Answer : Answer : b

A ____ operates on the magnetic attraction-repulsion principles.

Description : A ____ operates on the magnetic attraction-repulsion principles.

Last Answer : milliameter

What is that meter that depends for its operation on the forces attraction and repulsion

Description : What is that meter that depends for its operation on the forces attraction and repulsion

Last Answer : electrostatic instrument

During the formation of bond..... a) Energy decreases b) Energy increases c) Energy of system does not change d) Electron-electron repulsion becomes more than Nucleus-electron attraction

Description : During the formation of bond..... a) Energy decreases b) Energy increases c) Energy of system does not change d) Electron-electron repulsion becomes more than Nucleus-electron attraction

Last Answer : a) Energy decreases

PMMC type instruments normally use

Last Answer : PMMC type instruments normally use Eddy current damping.

The draft of a trailed type implement can be measured using a) Brake dynamometer b) Torque meter c) Tension dynamometer d) Dial gauge

Description : The draft of a trailed type implement can be measured using a) Brake dynamometer b) Torque meter c) Tension dynamometer d) Dial gauge Ans. c

Last Answer : Ans. c

Draw the construction and explain working principle of PMMC instruments

Description : Draw the construction and explain working principle of PMMC instruments

Last Answer : Working: When current passes through the coil a deflecting torque is produced. This deflecting torque is produced due to interaction between magnetic field produced by permanent magnet ... equilibrium; this is possible only when the controlling torque becomes equal to the deflecting torque 

Controlling torque in PMMC

Description : Controlling torque in PMMC

Last Answer : spring action

Derive the relation for deflection torque in PMMC instrument.

Description : Derive the relation for deflection torque in PMMC instrument. 

Last Answer : Ans: The length of coil be l meter and width of coil be d meter. Assume I is the current flowing in the ciol having N turns. Assume B as the flux density in the air gap then F=BIL ... a direct indication of the current in the coil. The pointer deflection can therefore be used to measure current.

Draw the diagram of PMMC instrument and state the deflection torque equation

Description : Draw the diagram of PMMC instrument and state the deflection torque equation

Last Answer : Equation Ʈ= B*A*I*N Where r= torque Newton. Meter B = flux density in the air gap. Wb/m2 A = effective coil area (m) N= number of turns of wire of the coil

The torque speed characteristic of a repulsion motor resembles which of the following d.c. motor

Description : The torque speed characteristic of a repulsion motor resembles which of the following d.c. motor characteristics  A) Separately excited B) Shunt C) Series D) Compound

Last Answer : The torque speed characteristic of a repulsion motor resembles which of the following d.c. motor characteristics Series 

In repulsion motor, zero torque is developed when?

Last Answer : In repulsion motor, zero torque is developed when brush axis coincides with the field axis and brush axis is 90° electrical to field axis.

Speed torque characteristic of a repulsion induction motor is similar to that of a D.C.?

Last Answer : Speed torque characteristic of a repulsion induction motor is similar to that of a D.C. compound motor.

In repulsion motor, maximum torque is developed when?

Last Answer : In repulsion motor, maximum torque is developed when brush axis is at 45° electrical to the field axis.

Moving coil in dynamometer wattmeter connected a) In series with fixed coil b) Across supply c) In series with load d) Across load

Description : Moving coil in dynamometer wattmeter connected a) In series with fixed coil b) Across supply c) In series with load d) Across load

Last Answer : Ans: Across supply

Moving coil in dynamometer wattmeter connected : -

Description :  Moving coil in dynamometer wattmeter connected : - a) in series with fixed coil b) across supply c) in series with load d) across load

Last Answer : Moving coil in dynamometer wattmeter connected : - across supply

In a dynamometer 3-phase power factor meter, the planes of the two moving coils are at?

Last Answer : In a dynamometer 3-phase power factor meter, the planes of the two moving coils are at 120°.

The resistance in the circuit of the moving coil of a dynamometer wattmeter should be?

Last Answer : The resistance in the circuit of the moving coil of a dynamometer wattmeter should be high.

Permanent Magnet Moving Coil (PMMC) Instrument

Description : Permanent Magnet Moving Coil (PMMC) Instrument

Last Answer : Permanent Magnet Moving Coil (PMMC) Instrument

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

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.

The main sources of Errors in Permanent Magnet moving Coil (PMMC) are due to : -

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

Which type of AC single-phase motor will also operate on direct current? A. Split-phase B. Series-wound C. Shaded-pole D. Repulsion-start

Description : Which type of AC single-phase motor will also operate on direct current? A. Split-phase B. Series-wound C. Shaded-pole D. Repulsion-start

Last Answer : Answer: B

Horizontally mounted moving iron instruments use

Description : Horizontally mounted moving iron instruments use   (a) Eddy current damping (b) Electromagnetic damping (c) Fluid friction damping (d) Air friction damping

Last Answer : Horizontally mounted moving iron instruments use Air friction damping

Consider the following statements with regard to Moving Iron (MI) instruments : 1. These instruments ...

Description : Consider the following statements with regard to Moving Iron (MI) instruments :  1. These instruments possess high operating torque.  2. These instruments can be used in ac and dc circuits.  3. Power consumption in these instruments ... and 2 only (b) 1 and 3 only (c) 2 and 3 only (d) 1, 2 and 3

Last Answer : Consider the following statements with regard to Moving Iron (MI) instruments :  1. These instruments possess high operating torque.  2. These instruments can be used in ac and dc circuits.  3. Power consumption in these ... 1 and 2 only (b) 1 and 3 only (c) 2 and 3 only (d) 1, 2 and 3

In moving iron instruments, eddy current damping cannot be used as

Description : In moving iron instruments, eddy current damping cannot be used as  (a) They have a strong operating magnetic, field (b) They are not normally used in vertical position (c) They ... of a permanent magnet required for eddy current damping would distort the existing weak operating magnetic field

Last Answer : In moving iron instruments, eddy current damping cannot be used as The introduction of a permanent magnet required for eddy current damping would distort the existing weak operating magnetic field

Moving iron instruments can be used for measuring

Description : Moving iron instruments can be used for measuring (1) Direct currents and voltages (2) Radio frequency currents (3) A.C currents and voltages (4) Both (a) and (c)

Last Answer : moving iron instruments areused to measure A.C curents &  voltages

In a moving iron meter, the deflecting torque is proportional to

Last Answer : In a moving iron meter, the deflecting torque is proportional to Square of the current through the coil.

The ratio of starting torque to full-load torque is least in case of?

Last Answer : The ratio of starting torque to full-load torque is least in case of shunt motors.

The most effective method of locating a loose commutator bar in a D.C. motor is by _____________. A. visual inspection B. jiggling each by hand C. sounding each bar with a light weight hammer D. checking with a calibrated torque wrench

Description : The most effective method of locating a loose commutator bar in a D.C. motor is by _____________. A. visual inspection B. jiggling each by hand C. sounding each bar with a light weight hammer D. checking with a calibrated torque wrench

Last Answer : Answer: C

Dynamometer type instrument can be used for

Description : Dynamometer type instrument can be used for

Last Answer : both dc and ac works

power of absorbing type hydraulic dynamometer varies as a) cube of rpm b) fifth power of the diameter c) none of the above d) both (a) and (b)

Description : power of absorbing type hydraulic dynamometer varies as a) cube of rpm b) fifth power of the diameter c) none of the above d) both (a) and (b)

Last Answer : d) both (a) and (b)

Draw and explain the circuit diagram for measurement of single phase power using dynamometer type wattmeter.

Description : Draw and explain the circuit diagram for measurement of single phase power using dynamometer type wattmeter. 

Last Answer : Circuit diagram for measurement of single phase power using dynamometer type wattmeter: Explanation: It consists of two stationary coils, called current coils and one moving coil, called voltage or ... i.e. power. The meter can be calibrated directly to indicate the power in watts. 

State the effects of errors in dynamometer type wattmeter due to i) pc- inductance ii) pc- capacitance iii) mutual inductance iv) Connection.

Description : State the effects of errors in dynamometer type wattmeter due to i) pc- inductance ii) pc- capacitance iii) mutual inductance iv) Connection.

Last Answer : Errors in wattmeter:  i) pc - inductance: Pressure coil inductance causes wattmeter to read more power than actual .  ii) pc-capacitance: The wattmeter reads less power.  iii) ... iv) Connection: In uncompensated wattmeter , the reading of wattmeter includes the powerloss in coils. 

State any four errors that occur in dynamometer type wattmeter

Description : State any four errors that occur in dynamometer type wattmeter

Last Answer : Errors that occur in dynamometer type wattmeter: 1. Errors due to method of connection. 2. Error due to pressure coil inductance. 3. Error due to pressure coil Capacitance. 4. Error due to mutual ... Error due to eddy currents. 7. Temperature error. 8. Error due to vibration of moving system

With a neat sketch explain working of 1 phase dynamometer type power factor meter.

Description : With a neat sketch explain working of 1 phase dynamometer type power factor meter.

Last Answer : Working of 1 phase dynamometer type power factor meter : The current coil is connected in series with load. Two pressure coils marked as A and B are connected across the supply terminals ... becomes stationary and the pointer shows steady deflection corresponding to the power factor of the load. 

With neat diagram explain constructional details of dynamometer type wattmeter.

Description : With neat diagram explain constructional details of dynamometer type wattmeter.

Last Answer : Working Principle of Wattmeter: It consists of two stationary coils, called current coils and one moving coil, called voltage or potential coil. The moving coil is mounted on the spindle, in the gap ... experiences a force and tends to move in the direction as per Fleming's left hand rule. 

In dynamometer type of wattmeter, which of the coil is split up into two parts?

Description :  In dynamometer type of wattmeter, which of the coil is split up into two parts?

Last Answer :  In dynamometer type of wattmeter, which of the coil is split up into two parts?  current coil