Electrical Measurements: Methods and Techniques

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What is the main advantage of the Direct Comparison method of measurements?

High accuracy with low uncertainty (correct)

Does not require comparison with a standard value

Requires minimal training and time

Can be carried out without a trained operator

Which method of measurement relies on achieving a balance in weight to determine the unknown current?

Indirect measurement method (correct)

Differential measurement method

Substitution method

Null measurement method

Which of the following is a characteristic of the Substitution method of measurements?

No need for any standard value

Uses digital output readings

Standard resistance is adjusted until a balance is reached (correct)

Measurement relies on continuous monitoring

What is a key feature of the null measurement method?

Balancing state indicated by zero current only Signup and view all the answers

In which type of measuring instruments are damping forces used to ensure stability of the pointer?

Mechanical instruments Signup and view all the answers

What distinguishes Digital instruments from Analogue instruments in terms of signal representation?

Discrete number representation Signup and view all the answers

Which type of measurement instruments have two types of scales: linear and non-linear?

Analogue instruments Signup and view all the answers

In which method can a roughly balanced state lead to pointer deflection or a change in output reading due to differences in equilibrium and actual states?

Null-Differential measurement method Signup and view all the answers

What type of force is used in Analogue instruments to prevent continuous movement of the pointer to its maximum deflection?

Controlling force Signup and view all the answers

Which method of measurements does not require standard current values for measurement?

Null measurement method Signup and view all the answers

Which type of instrument is used only for direct current measurements?

Permanent magnet moving coil (PMMC) Signup and view all the answers

What is the primary factor that causes the pointer to initially overshoot its steady-state position in an analog instrument?

The inertia of the moving parts Signup and view all the answers

Which type of control torque produces a restoring force that is proportional to the deflection angle?

Spring control Signup and view all the answers

For a gravity-controlled instrument, the current is proportional to which function of the deflection angle?

The sine of the angle Signup and view all the answers

What is the primary advantage of gravity-controlled instruments over spring-controlled instruments?

They are cheaper to manufacture Signup and view all the answers

Which equation describes the relationship between the deflecting torque and the current in an instrument?

$T = K \cdot i$ Signup and view all the answers

In the equation of motion for an analog instrument during the transient period, what does the term $T_i$ represent?

The inertia torque Signup and view all the answers

Which property of the spring material is essential for ensuring accurate measurements in spring-controlled instruments?

All of the above Signup and view all the answers

What is the primary disadvantage of gravity-controlled instruments?

They have a non-uniform scale Signup and view all the answers

Which type of instrument is primarily used for alternating current measurements?

Induction type Signup and view all the answers

What is the relationship between the deflecting torque and the current in an instrument?

The deflecting torque is proportional to the square of the current. Signup and view all the answers

If the current producing a deflection angle of 90° is 2 A, what current is required to produce a deflection angle of 45° assuming spring control?

1.4142 A Signup and view all the answers

What is the purpose of damping torque in an instrument?

To stabilize the motion and prevent oscillations around the final position. Signup and view all the answers

Which type of damping is NOT effective in many situations?

Air damping Signup and view all the answers

What is the principle behind eddy current damping?

The flow of eddy currents in a conductive disc produces a damping force according to Lenz's law. Signup and view all the answers

What is the advantage of over-damped performance in an instrument?

The pointer moves slowly to its final value without oscillations. Signup and view all the answers

Which performance type is characterized by low damped behavior and high oscillations that decay with time?

Under-damped Signup and view all the answers

What is the characteristic of critical-damped performance?

The pointer moves faster than over-damped but slower than under-damped, without oscillations. Signup and view all the answers

If the damping constant is less than $4\sqrt{CJ}$, what type of performance can be expected?

Under-damped Signup and view all the answers

What is the relationship between the damping torque and the angular velocity of the pointer?

The damping torque is independent of the angular velocity. Signup and view all the answers

What is the main difference between linear and non-linear scale instruments?

Non-linear scale instruments have overcrowded graduations at the beginning of the scale, while the graduations are evenly spaced in linear scale instruments. Signup and view all the answers

Which of the following is a key characteristic of mechanical measuring instruments?

They are characterized by their heavy weight, large size and high prices. Signup and view all the answers

What is the main advantage of digital instruments over mechanical and electrical instruments?

Digital instruments provide automatic range adjustment. Signup and view all the answers

Which type of measuring instrument is suitable for measuring steady and stable operations?

Mechanical instruments Signup and view all the answers

What is the main disadvantage of electrical measuring instruments compared to electronic instruments?

Electrical instruments have a higher possibility for faults and problems. Signup and view all the answers

What is the main advantage of a graphical display over a pointer display in analogue instruments?

Graphical displays can display the magnitude and type of variation of the measured variable. Signup and view all the answers

What is the main advantage of a digital display over an analogue display?

Digital displays provide more accurate and definite readings. Signup and view all the answers

Which physical effect is utilized in ammeters and voltmeters?

Electromagnetic effect Signup and view all the answers

Which type of measuring instrument is suitable for measuring transient and dynamic applications?

Electronic instruments Signup and view all the answers

What is the main disadvantage of pointer-type analogue displays?

Pointer devices have the problem of parallax, which can cause an error in the reading. Signup and view all the answers