Industrial Instrumentation MCQs

Practice Industrial Instrumentation MCQs with four options, answers and explanations for focused Electronics & Telecommunication Engineering revision.

Question 1

Measurements & InstrumentationIndustrial Instrumentation

In a 4-20 mA industrial current loop, the value 4 mA commonly represents?

ALive zero or lower-range value
BFull-scale value
CPower failure by definition
DExactly 25% of every physical quantity

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Correct Answer: A. Live zero or lower-range value

Explanation: The 4 mA lower endpoint is a live zero, helping distinguish a valid minimum reading from certain fault conditions such as an open loop.

Reference: Standard measurements and instrumentation: industrial instrumentation

Question 2

Measurements & InstrumentationIndustrial Instrumentation

For a linear 4-20 mA transmitter calibrated for 0-100 °C, an output of 12 mA corresponds to?

A25 °C
B50 °C
C75 °C
D100 °C

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Correct Answer: B. 50 °C

Explanation: 12 mA is halfway between 4 and 20 mA, so it represents 50% of span, or 50 °C.

Reference: Standard measurements and instrumentation: industrial instrumentation

Question 3

Measurements & InstrumentationIndustrial Instrumentation

A 4-20 mA pressure transmitter covers 0-200 kPa. What current ideally represents 150 kPa?

A8 mA
B12 mA
C16 mA
D20 mA

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Correct Answer: C. 16 mA

Explanation: 150/200=0.75 of span. Current=4 mA+0.75×16 mA=16 mA.

Reference: Standard measurements and instrumentation: industrial instrumentation