7/25/2019 II-II - EM&I - Unit-II - Question Bank

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VIGNANS UNIVERSITY:: VADLAMUDI

EE216 - Electrical Measuremets ! Istrumetati" #EM!I$

UNIT % II

&uesti" 'a(

)NE Mar( &uesti"s

Write the equation for transformation ratio in C.T

Draw equivalent circuit of C.T

Why the secondary of C.T should not be opened?4. What is main use of instrument transformers?

What are the types of instrument transformers?

What are the types of frequency meters?Define phase angle error

What is the transformer type that acts like step down transformer?

Write any two differences between current transformer and potential transformer.

n frequency meter controlling torque is provided bya! "ravity b! #pring c! there is no controlling torque d!none of these

The electrodynamometer types of instruments are used as?

Define power factor.Write any two advantages of instrument transformers

Define turns ratio

What is the fi$ed coil of electrodynamometer known as?

The dynamometer type instrument has uniform scale when used as?The instrument transformers are primarily used for which type of supply?

What is the function of synchroscope?%ow instrument transformers differ from power transformers

Write torque equation for electrodynamometer type meters.

What are the advantages of & type 'ower factor meters?

Define ratio (rror?What are the different types of 'ower factor meter.

What is phase angle and on what factors does it depend?

)ame different coils in electrodynamometer type meters

T*) Mar( &uesti"s

*. What is meant by nominal ratio in instrument transformers?

+. What is meant by transformation ratio in instrument transformers?

,. Define ratio correction factor.

7/25/2019 II-II - EM&I - Unit-II - Question Bank

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4. Define phase angle of the transformer.

-. Write the principle of operation of Dynamometer type instrument.

. Write principle of operation of resonant type frequency meter

/. What are the different errors in instrument transformers?

0. What are the disadvantages of dynamometer type power factor meter?

1. %ow can the ratio and phase angle errors in the potential transformers be reduced ?

*2. Write the advantages of moving iron power factor meters

**. Write the disadvantages of moving iron power factor meters

+IVE Mar( &uesti"s

*. 3 current transformer of turns ratio **11 is rated as *2025- 3

and +- 63 with magneti7ing current of /3 and loss current of

43 under the rated condition. Determine the phase angle and

ratio error at 2.0 pf lag and 2.0 pf lead. )eglect the resistance

and leakage reactance of secondary winding.

+. Compare current transformer and potential transformer.

,. ($plain with neat diagram8 the working of Weston type frequency meter.

4. ($plain the construction and working of , phase rotating power factor meter.

-. Write a short note on &echanical resonance type frequency meter.

. Describe the constructional details and working of *9phase electrodynamometer power

factor meter.

/. Derive the e$pression for ratio error and phase angle error of CT.

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0. Define the terms a! Transformation ratio b! )ominal :atio c! :atio correction factor and d!

Turns ratio for both CT and 'T.

1. ($plain with neat diagram8 the working of Weston type synchroscope.

*2. ($plain with neat diagram8 the working of moving iron type synchroscope.

TEN Mar( &uesti"s

*. a! Derive the e$pressions for ratio error and phase angle error of a CT

;current transformer!

b! 3 current transformer with a bar has ,22 turns in its secondary winding. The

resistance and reactance of the secondary circuit are *.-< and *.2 < respectively

including the transformer winding. With -3 flowing in the secondary winding8 the

magneti7ing mmf is *22 amperes and iron loss is *.+ watts. Determine the ratio

error

+. a! Describe the constructional details and working of *9phase moving iron power

factor meter

b! ($plain the meaning of the term =burden> with respect to instrument transformers

,. a! ($plain the working of a frequency meter which depends for its action on the

phenomenon of electrical resonance

b! Describe the constructional details and working of , electro dynamometer type power

factor meter.

4. a! 3 *2225-38 -2%7 current transformer has a secondary burden comprising of a non9

inductive impedance of *.

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with non inductive burden the in phase and quadrature components ;referred

to flu$! of the e$citing mmf are 3T and 0 3T respectively. Calculate the

current and phase angle error.