Practice Test Geeks(EETC) Electrical Technician Certification Practice Test
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Instrumentation Flashcards

7 cards from real EETC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Instrumentation flashcards as text

  1. Which type of pressure measurement compares process pressure to atmospheric pressure?

    Answer: Gauge pressure

    Gauge pressure (psig) uses atmospheric pressure (14.696 psia at sea level) as its reference, so a reading of 0 psig equals atmospheric.

  2. A pH sensor outputs approximately how many millivolts per pH unit at 25°C?

    Answer: 59.16 mV/pH

    The Nernst equation predicts approximately 59.16mV/pH unit response for a glass electrode at 25°C (298K).

  3. An orifice plate in a pipeline causes flow measurement errors when:

    Answer: The upstream straight pipe run is too short

    Insufficient straight pipe upstream causes turbulent or asymmetric velocity profiles that deviate from the conditions assumed in the orifice calibration.

  4. In a HART (Highway Addressable Remote Transducer) system, digital communication is superimposed on the 4-20mA signal using:

    Answer: FSK at 1200 baud over the analog loop

    HART uses Bell 202 FSK (Frequency Shift Keying) — 1200Hz for logic '1' and 2200Hz for logic '0' — overlaid on the DC 4-20mA signal without disrupting it.

  5. What is the purpose of a cold junction compensation circuit in a thermocouple instrument?

    Answer: To correct for the ambient temperature at the reference junction

    Cold junction compensation measures the terminal block temperature and adds the equivalent voltage so the instrument reads true process temperature regardless of ambient conditions.

  6. A Coriolis flow meter measures which two fluid properties simultaneously?

    Answer: Mass flow and density

    The Coriolis effect on vibrating tubes directly measures true mass flow rate, and tube frequency shift simultaneously yields fluid density.

  7. Which wiring configuration eliminates lead resistance error in RTD measurements?

    Answer: 4-wire (Kelvin)

    In a 4-wire (Kelvin) configuration, separate current-source and voltage-sense lead pairs ensure that no voltage drop across lead resistance is included in the measurement.