Transcript No Slide Title

Crosscutting Laboratories
For better
Comprehension and
Retention
Steve Larson
Lawrence Beaty
HI TEC July 2014
Background
• One of the challenges in the education of students about
STEM concepts is developing methods to teach fundamental
principles while keeping the value of those fundamentals
relevant to students.
• It is far too easy for the actual application and usefulness of
technical theory to become isolated from application in such
a way as to cause the student to “silo” the knowledge they
have gained separately from its practical application.
• When this occurs students are far more likely to rely upon
rote memory rather than the mastery of concepts and use
memorization and the following of procedures rather than
critical thinking in solving problems.
Why develop these Crosscutting
Concepts?
• Crosscutting concepts can help students better
understand science and engineering practices.
• Crosscutting concepts address multiple disciplines
and consider the fundamental way things work.
• They provide a platform to look at multiple
applications for the same idea or concept.
• Different crosscutting concepts align with both
scientific and analytical thought
The RTD Lab
• The lessons developed provides practical and low cost
platforms to integrate scientific application and classical
STEM theory. One of the systems developed combines the
very practical concept of measuring a temperature and
transmitting that measurement value over a 4-20mA
current loop with the application of several theoretical
concepts such as an the bridge circuit, Thévenin's theorem,
material properties of conductors, the principle of latent
heat and several other electronic and physics concepts into
a single exercise.
The System
A PT100 4-20 mA Transmitter produces a current relative to
the temperature being measures. If measuring a temperature
range between 200 degrees Fahrenheit and 400 degrees
Fahrenheit the transmitter would produce 4 mA at 200
degrees and 20 mA at 400 degrees and should have a linear
signal for all temperatures in between.
A platinum resistance temperature detector
(RTD) Pt100 is a device with a resistance of 100
Ω at 0°C .It changes resistance value as its
temperature changes following a positive
slope (resistance increases when temperature
is increasing).
RTD Calibration Procedure
• Connect the current meter where labeled.
• Connect the voltage meter across the 250Ω resistor.
• Start the hot plate to boil the pan of water. (Use caution as
the power supply is plugged into 120 volts).
• Place the RTD Probe into the boiling water.
• After a short period of time, at least 3 to 5 minutes. The
current meter should read 20 mA (If not adjust the trim pots
to achieve the desired 20 mA).
Basic Procedure Continued
• Place the RTD into a glass of ice water.
• After a short period of time, at least 3 to 5 minutes. The
Current meter should read 4mA (if not adjust the trim pots
to achieve the desired 4 mA).
• Place the RTD back into the boiling water to recalibrate if
needed at 20 mA.
• Place the RTD back into the Ice bath to recalibrate if needed
at 4 mA .
What are some additional ideas that
can be taught from this lab?
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Ohm’s Law
4-20 mA process measurement
Calibration
Heat transfer concepts
Thevenin’s principles
Material Properties
Current Loops
Meter Loading
Temperature
Bridge Circuits
Thanks You
• Question?
• Presentations, parts list and other
information available at:
www.isu.edu/estec