1 Answer

Answer :

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

Related questions

Description : 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

Last Answer : Ans: A

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

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

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

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

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 

Description : In a PMMC instrument, the damping provided is :  (A) air damping (C) eddy current damping (B) fluid damping (D) magnetic damping using a magnet

Last Answer : In a PMMC instrument, the damping provided is : eddy current damping 

Description : A PMMC instrument has FSD of 100 μA and a coil resistance of 1 kΩ. To convert the instrument into an ammeter with full scale deflection of 100 mA, the required shunt resistance is (A) 1 Ω (B) 1.001 Ω (C) 0.5 Ω (D) 10 Ω

Last Answer : A PMMC instrument has FSD of 100 μA and a coil resistance of 1 kΩ. To convert the instrument into an ammeter with full scale deflection of 100 mA, the required shunt resistance is 1.001 Ω

Description : PMMC instrument gives uniform scale because:

Last Answer : PMMC instrument gives uniform scale because: It uses spring control and The deflection torque is proportional to the instrument current.

Last Answer : A PMMC instrument can be used as a fluxmeter by: Removing the control spring

Description : Permanent magnet moving coil instruments are used for

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

Description : Permanent Magnet Moving Coil (PMMC) Instrument

Last Answer : Permanent Magnet Moving Coil (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.

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

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

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

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

Description : An unshielded moving iron voltmeter is used to measure the voltage in an AC circuit. The stray DC magnetic field having a component along the axis will be  (1) unaffected (2) decreased (3) increased (4) either decreased or increased depending on the direction of the DC field

Last Answer : An unshielded moving iron voltmeter is used to measure the voltage in an AC circuit. The stray DC magnetic field having a component along the axis will be either decreased or increased depending on the direction of the DC field

Description : Eddy current damping cannot be used for moving iron instrument because

Last Answer : Eddy current damping cannot be used for moving iron instrument because the presence of a permanent magnet required for such purpose would affect the deflection and hence the reading of the instrument

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

Last Answer : A moving iron ammeter may be compensated for frequency errors by shunt capacitance.

Last Answer : The moving iron voltmeters are likely: To indicate lower value of ac than on dc.

Description : A 150 V moving iron voltmeter of accuracy class 1.0 reads 75 V when used in a circuit under a standard conditions. The maximum possible percentage error in the reading is:

Last Answer : A 150 V moving iron voltmeter of accuracy class 1.0 reads 75 V when used in a circuit under a standard conditions. The maximum possible percentage error in the reading is:  2.0.

Last Answer : A moving iron instrument can be used for both D.C. and A.C.

Description : Which of the following instruments can be used for measurement of very high value resistances such as insulation resistance in industries? A) Wheatstone bridge B) Megger C) Ohm-meter D) Resistive potentiometer 

Last Answer : Which of the following instruments can be used for measurement of very high value resistances such as insulation resistance in industries? A) Wheatstone bridge B) Megger C) Ohm-meter D) Resistive potentiometer 

Description :  Highest flux density exists inside which of the following instruments? A) Electrodynamic instruments B) Hot wire instruments C) Moving iron instruments D) Moving coil instruments

Last Answer : Highest flux density exists inside which of the following instruments? A) Electrodynamic instruments B) Hot wire instruments C) Moving iron instruments D) Moving coil instruments 

Description : The type of instruments used mainly for standardizing instruments in laboratories is (a) Indicating instrument (b) Integrating instrument (c) Absolute instrument (d) Recording instrument  

Last Answer : Ans:Option C

Description : Eddy current damping is normally used in the instruments of (a) Induction type (b) Moving iron type (c) Permanent magnet moving coil type (d) Nothing can be said 

Last Answer : Permanent  magnetic  moving  coil  instrument.

Description : Electrostatic type instruments are primarily used as 

Last Answer : Voltmeter

Description : The force required to move the pointer in an indicating instruments is

Last Answer : The force required to move the pointer in an indicating instruments is deflecting force

Last Answer : Thermocouple instruments are also known as Rectifier instruments.

Last Answer :  Electrostatic instruments are normally used for High voltage measurements.

Description : Which of the following instruments can be used to measure AC current only? (a) Permanent Magnet Type ammeter(b) Induction type ammeter (c) Moving iron voltmeter(d) Moving iron ammeter

Last Answer : (b) Induction type ammeter

Last Answer : Jewels are used in instruments for the purpose of Bearing.

Last Answer : The thermocouple instruments do not have High degree of measuring accuracy.

Last Answer : The electrostatic instruments can be used without serious loss of accuracy upto 100kHz frequency.

Last Answer : Integrating instruments are those which measure the total quantity of electricity delivered in a particular time.

Description : The use of _____ instruments is merely confined within laboratories as standardising instruments.

Last Answer : The use of absolute instruments is merely confined within laboratories as standardizing instruments.

Last Answer : Air friction damping is used in the instruments which is: Moving iron

Last Answer : Commonly used instruments in power system measurement are induction.

Last Answer : Operating torques in analogue instruments are deflecting, control and damping.

Last Answer : The power factor of a single phase load can be calculated if the instruments available are three ammeters or three voltmeters.

Last Answer : The switch board instruments should be mounted in vertical position.

Last Answer : In the majority of instruments, damping is provided by eddy currents.

Last Answer : According to application, instruments are classified as switch board, portable.

Last Answer : Integrating instruments are those which measure the total quantity of electricity delivered in a particular time.

Last Answer : The use of absolute instruments is merely confined within laboratories as standardizing instruments.

Description : What do you mean by secondary instruments?

Last Answer : The instruments which will give the direct readings are called secondary instruments

Description : The most distinguished property of malleable cast iron is its high (A) Ductility (B) Hardness (C) Malleability (D) None of these

Last Answer : (A) Ductility

Description : How can a colloidal solution and true solution of the same colour be distinguished from each other?

Last Answer : Ans.: By Tyndal effect( colloidal solution will scatter light and path becomes lighted where as no such phenomena is observed in true solution.)