Type of household energy meter: Identify whether a domestic electricity (kWh) meter is indicating, recording, or integrating in nature.
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Aindicating instrument
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Brecording instrument
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Cintegrating instrument
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Dnone of the above
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Enull-type instrument
Answer
Correct Answer: integrating instrument
Explanation
Introduction / Context:Domestic energy meters installed by utilities display cumulative electrical energy consumption, typically in kilowatt-hours (kWh). Distinguishing among indicating, recording, and integrating instruments is part of basic measurement science and is often featured in introductory electrical engineering curricula.
Given Data / Assumptions:
- Household meter accumulates energy use over time.
- Display may be electromechanical dials or electronic LCDs, but the functional principle is the same.
- Energy is the time integral of instantaneous power.
Concept / Approach:
An indicating instrument shows instantaneous value (e.g., voltmeter, ammeter). A recording instrument logs a time history (chart recorders). An integrating instrument accumulates a quantity over time; a kWh meter integrates power (kW) with respect to time to yield energy (kWh). Therefore, a household energy meter is an integrating instrument.
Step-by-Step Solution:
Define energy: E = ∫ P(t) dt.Meters implement E accumulation mechanically (Ferraris disk) or digitally (sampling and computation).The register displays cumulative kWh, not instantaneous kW or a plotted trace.Verification / Alternative check:
Modern smart meters still report totalized kWh between billing cycles; instantaneous power is optional telemetry but the billing core remains integrated energy, confirming the classification.
Why Other Options Are Wrong:
- Indicating: would show instantaneous power only.
- Recording: implies a continuous time record; traditional meters do not plot a chart of P(t).
- None/null-type: not applicable to kWh metering function.
Common Pitfalls:
- Confusing real-time demand (kW) displays in smart meters with the legal billing quantity (kWh).
Final Answer:
integrating instrument