ac test questions Flashcards
I am the sensing device that detects the condition of the process variable Who am I?
Primary Element
A bonded wire strain gauge is used in what type of comparator circuit allowing a small change in resistance to cause a voltage variation
A Bridge comparator
I operate by sending sound waves toward the target and measuring the time it takes for the pulses to bounce back Who am I?
Ultrasonic Sensor
How is an inductive proximity sensor actuated ?
by a metal object
The _______ is a non-contact temperature detector that can measure the infrared radiation emitted from an object. Thus making it possible to measure temperatures from a remote location. the infrared radiation is often focused onto a thermopile or an LDR
Pyrometer
A stainless steel sheath thermocouple when heated produces what
a small dc voltage
What does signal conditioning involve
Converting input and output signals to a usable form
There is a strain gauge mounted on the outside of a tube. the force applied to this sensor causes it to bend and change its
resistance
A strain gauge under tension has its resistance affected according to the following relationship R = kL / cma
therefore the strain gauge resistance will
increase due to decreased cross sectional area and increased length
A shaft encoder is coupled to the output shaft of an electric motor. The output of the shaft encoder is connected to a positioner controller. Which specification detail for the encoder will determine the resolution of the positioning system.
Pulses per revolution
A new steady-state condition occurs ______ time constant(s) after a controlled variable is exposed to an energy change.
5
I am sent to the final control element Who am i
Control signal
Compared to an open loop system closed loop control systems
Require feedback concerning the status of the process
generally what is the essential difference between an open loop and a closed loop control system
Closed loop systems incorporate feedback
two ingredients are added together, processed and then stored within an industrial bakery.
this is an example of
batch process
What type of maintenance technicians are becoming more popular in the industry due to their flexibility and cost effectiveness
multi skilled technicians
which elements and signals of a control system do not exist in an open loop configuration
- comparator
- error signal
- summing amplifier
- feedback signal
- all of the above
all of the above
of the devices listed below
- motor
- heater
- fan
which could classify as an actuator
all of them
which of the following devices could be classified as a sensor
- thermistor
- clutch
- relay
- LED indicator
thermistor
I am an electrical meter consisting of several thermocouples connected in series to provide a higher voltage output who am i
Thermopile
This meter uses a strip consisting of two metal alloys with different coefficients of thermal expansion that are fused together and formed into a single strip complete with an indicating mechanism calibrated for temperature reading who am i
Bimetallic
A thermistor requires which type of signal conditioning
Cold junction compensation
Solids transfer thermal energy by which process
Conductance
When testing an RTD or a thermistor why is it necessary to disconnect it from the circuit
the transducer must be isolated from the other circuit components that would affect the measurement
What does the V stand for in this formula | Q= VA
velocity
which of these are classified as fluids
-solids
-gasses
-liquids
-vapors
gasses liquids and vapors
