Author Archive | Mark Weisner

XP Virtual 2

Virtual Boxes

In preparing for our updated suite of cybersecurity classes one idea that has come to the forefront is to set up virtual computers aka: appliance or machines. This would enable us to let our students experiment and not cause damage to the physical computer. I have spent many hours in the last 3 weeks testing […]

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Function Block

IEC 6-1131-3

The IEC (International Electrotechnical Commission) 6-1131-3 Standard is a widely recognized international standard for the programming of a PLC. How many ‘Graphical languages’ are there in the IEC  6-1131-3  ? a.  2 b.  3 c.  4 d.  5 The correct answer is A. They are Ladder Diagram (LD) and  Function Block Diagram (FBD). Ladder Diagram […]

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AD Converters Quiz: convert an analog signal to a digital one

AD Converters are necessary to convert an analog signal to a digital one that our computers can understand. The output of an AD Converter is a binary number. Digital instruments most commonly use 12, 14 and 16-bit converters, although there are much higher bit converters available. The following is a practice question from one of […]

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cv formula

A Little About Valves

What is Cv ? If you are a mechanic, you would probably say that it is the joints that are on a front wheel drive vehicle, however if you work in the field of process automation you might know that it pertains to control valves. Cv is the capacity of a control valve, or the […]

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Estimated Standard Deviation

Because an exact number for standard deviation could only be obtained by taking an infinite number of measurements, the below formula calculates the estimated standard deviation. Let’s take a set of measurements from a temperature transmitter with a range of 0-100 deg, Celsius. IDEAL VALUES     AS FOUND VALUES 0 1 10 12 20 21 30 […]

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Linear Relationships for 4-20 mA transmitters

Linear Relationships for 4-20 Transmitters A standard electronic pressure transmitter has a range of 50 to 250 psig (345 to 1724 kPa gage), and the pressure is 150 psig (1034 kPa gage), what is the output in mA? a.   4.0 mA b.   12.0 mA c.   13.6 mA d.   50.0 mA   The formula I use […]

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Square root formula

Evaluation Question

An analog electronic d/p transmitter has an output of 4-20 mA which represents 0 to 100 gpm (0 to 378.5 lpm). On a properly calibrated transmitter, what is the output in gpm (lpm), if the transmitter output is 12 mA?          a.    25                 (94 lpm)          b.   33.3             (126 lpm)          c.   70.7             (267.6 […]

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Cal Workbook

Spreadsheets are tools

In trying to decided on a blog topic, I thought of the spreadsheet we did in our Applying Motor Controls and Drives class last week for showing the voltage and hertz relationship. We then used the chart wizard and selected a scatter point type of chart. I then started thinking about the calibration sheet we do […]

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