An angular position to be measured using a transducer. Which of the following types of transducers can be used for this purpose ? 1. Circular potentiometer Select the correct answer using the codes given below : Codes :
2. LVDT
3. E-pick off
4. Synchro
1 and 4
The test is simple: does the device respond to rotation or to straight-line motion?
| Transducer | Measures | Angular? |
|---|---|---|
| Circular potentiometer | Shaft angle, as a resistance ratio | ✓ |
| LVDT | Linear displacement of a core | ✗ |
| E-pick off | Small displacement, usually linear | Marginal |
| Synchro | Shaft angle, as a set of stator voltages | ✓ |
LVDT is the decisive exclusion. The name spells it out — Linear Variable Differential Transformer. A movable magnetic core slides along the axis of one primary and two opposed secondaries, and the differential output is proportional to its straight-line travel. Its rotary counterpart exists and is called the RVDT; had the question offered that, it would have belonged in the list. Any option containing 2 is therefore wrong, which eliminates options 1, 2 and 3 at once and leaves option 4.
How the two accepted devices work.
The circular potentiometer is a resistive track bent into an arc with a wiper on the shaft. The output is a simple fraction of the excitation:
\(V_{o}=V_{ex}\dfrac{\theta}{\theta_{t}}\)
Cheap and linear, but it has a sliding contact that wears and a limited resolution.
The synchro is a small rotating transformer: a single-phase rotor winding excited by AC induces voltages in three stator windings 120° apart, whose ratios encode the shaft angle unambiguously over a full revolution. It is contactless in the sensing sense, rugged, and can transmit an angle over a pair of wires to a receiving synchro — which is why synchros dominated aircraft and naval instrumentation.
On the E-pick off : the E-shaped laminated core with a coil on each limb is an inductive transducer whose output depends on the position of an armature above it. It is normally described as a displacement sensor, and although it can be arranged to sense small angular movements, the question's option set never offers a combination containing 3 without also containing 2, so it cannot be selected here. That is why the answer is flagged for confirmation.
Hence, the transducers usable for angular position are 1 and 4.
Similar Questions
An LVDT is used for measuring the deflection of bellows. The sensitivity of LVDT is 40V per mm. The bellows is deflected by 0.125 mm by a pressure of 0.8 x 106 N per m2. Determine the sensitivity of the LVDT in V per N/m2, when the voltage output of LVDT is 3.1 V.
Consider the following statements regarding the advantages of Anderson Bridge
A. It is the modification of the Maxwell's inductance Capacitance Bridge
B. For measuring the low Q of coils, it is not superior to Maxwell's bridge
C. It is not simple as compared to Maxwell's Bridge
D. It can be used to determine mutual inductance
Choose the correct answer from the options given below:
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R
Assertion A : Potentiometric type accelerometer have higher resolution than LVDT accelerometer.
Reason R : The resistance offered to the motion is less in LVDT accelerometer than in potentiometric accelerometer.
In the light of the above statements, choose the most appropriate answer from the options given below :
An LVDT has the following data : input = 6.3 V, Output = 5.2 V, range = ± 0.5 cm. The value of output voltage, when it is at 0.45 cm from the centre is given by
Important Questions from Inductive Transducers - Teaching
An LVDT is used for measuring the deflection of bellows. The sensitivity of LVDT is 40V per mm. The bellows is deflected by 0.125 mm by a pressure of 0.8 x 106 N per m2. Determine the sensitivity of the LVDT in V per N/m2, when the voltage output of LVDT is 3.1 V.
Consider the following statements regarding the advantages of Anderson Bridge
A. It is the modification of the Maxwell's inductance Capacitance Bridge
B. For measuring the low Q of coils, it is not superior to Maxwell's bridge
C. It is not simple as compared to Maxwell's Bridge
D. It can be used to determine mutual inductance
Choose the correct answer from the options given below:
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R
Assertion A : Potentiometric type accelerometer have higher resolution than LVDT accelerometer.
Reason R : The resistance offered to the motion is less in LVDT accelerometer than in potentiometric accelerometer.
In the light of the above statements, choose the most appropriate answer from the options given below :
An LVDT has the following data : input = 6.3 V, Output = 5.2 V, range = ± 0.5 cm. The value of output voltage, when it is at 0.45 cm from the centre is given by
