CAS Automation Specialist Instrumentation & Sensors Flashcards

Which sensor technology is best suited for detecting the presence of non-metallic objects without contact?

Answer: Capacitive proximity sensor

Capacitive proximity sensors detect changes in capacitance caused by any material (metallic or non-metallic) entering their sensing field.

What is 'dead band' in the context of a process instrument or controller?

Answer: A range of input values over which no change in output occurs, used to prevent hunting

Dead band is an intentional range of input change that does not cause an output change, reducing unnecessary actuator movement and wear.

In a magnetic flowmeter, what is the primary requirement regarding the process fluid?

Answer: The fluid must have a minimum electrical conductivity

Magnetic flowmeters (magmeters) operate on Faraday's law and require the fluid to have a minimum conductivity (typically ≥5 µS/cm) to generate a measurable EMF.

What does 'intrinsic safety' (IS) mean in hazardous area instrumentation?

Answer: The electrical energy in the circuit is limited so it cannot ignite a flammable atmosphere

Intrinsic safety limits the electrical energy (voltage, current, capacitance, inductance) in a circuit to levels that cannot ignite a specified flammable atmosphere.

In the ISA-5.1 standard for instrumentation symbols, what shape represents a shared display/shared control function (e.g., a DCS controller)?

Answer: A circle with a horizontal line through it

ISA-5.1 uses a circle bisected by a horizontal line to represent a function accessible from a shared display/shared control (DCS) system.

Which calibration concept describes the maximum deviation between an instrument's output and the true value across its full operating range?

Answer: Accuracy

Accuracy (or total error) is the maximum deviation of an instrument's indication from the true value, typically expressed as ±% of full scale.