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Motor Intended Duty Sorter

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About This MicroSim

The intended duty on a motor line (the "SD" in FanPedia's example line) says how well the whole motor stands up to its surroundings. Choosing it is a judgment against FanPedia's stated rules, not a recall of a list. This MicroSim shows eight illustrative inquiries, one at a time and always in the same order. For each one you choose one of five duty bins and commit it with Check.

Bin Definition (shown when the bin is open)
GD (General Duty) General purpose motor for normal, clean and cool air around the motor.
SD (Severe Duty) Used where a severe duty motor is needed but IEEE 841 is not specified; also called Mil/Chem duty or chemical duty.
IEEE 841 Industry standard for severe duty motors begun in 1986, used in process industries when specified.
DFG Explosion proof enclosure motor for a hazardous location classified under the NEC.
Washdown Special-basis motor for food applications that are washed down.

Each case has one attempt. A correct choice reads "✓ Correct: . "; an incorrect one reads "✗ Not quite. The correct duty is . ". The correct duty is shown at once, and a checked case cannot be changed. Each checked case stays marked in the bin you chose, as a chip with its case number and ✓ (solid border) or ✗ (dashed border). The running line reads "Correct: n of 8".

After case 8 the summary gives the first-attempt score, says whether the mastery level (7 of 8 on the first attempt) was reached, and lists all eight cases with your bin, the correct bin and the reason. On narrow screens the list is split over two pages.

The rules come from FanPedia p. 73 as presented in Chapter 15: a case that names IEEE 841 is IEEE 841; a severe case that does not name it is SD; only the owner's NEC area classification makes a location hazardous (DFG). The cases are illustrative.

How to Use

  1. Read the case and the prompt "Which intended duty does this motor need?"
  2. Choose a bin with its button or keys 1 to 5. Choosing a bin opens its definition; you can change your choice until you press Check. Press Open all definitions (or D) to open all five at once.
  3. Press Check (or Enter). Read the verdict and the reason.
  4. Press Next case (or Enter). After case 8, press Finish and read the summary.
  5. Start over clears the score and starts again at case 1.

Keyboard: keys 1 to 5 choose a bin; D opens or closes all definitions; Enter checks, then goes to the next case; Tab reaches every button.

Data label: "Illustrative cases · Rules: FanPedia p. 73", shown at the bottom left of the drawing.

Iframe Embed Code

You can add this MicroSim to any web page by adding this to your HTML:

<iframe src="https://moroshek.github.io/FanTASTIC-textbook/sims/ch15-motor-intended-duty-sorter/main.html"
        height="602px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Learning Objective

The learner will judge which motor intended duty (GD, SD, IEEE 841, DFG or Washdown) an application requires, given a short description of the motor's environment and the customer's specification, with at least 7 of 8 cases correct on the first attempt (Bloom: Evaluate, verb: judge).

Audience

Adult professional development: new application engineers, sales staff, representatives and facilities staff.

Duration

10-15 minutes

Prerequisites

  • Motor intended duty and general duty (Chapter 15, "Motor Intended Duty")
  • Severe duty motor and IEEE 841 (Chapter 15, "Severe Duty Motor")
  • Hazardous location motor, NEC class, division and group, DFG (Chapter 15, "Hazardous Location Motor")
  • Washdown duty motors ordered on a special basis (Chapter 15)

Activities

  1. Sort (6 min): Work through the eight cases. Before pressing Check, say which words in the case decide the duty.
  2. Review (4 min): Read the summary. For each miss, name the FanPedia rule that decides it.
  3. Discuss (3 min): Cases 3 and 7 and cases 2 and 8 describe similar environments but get different duties. What in the specification makes the difference?

Common Misconceptions Addressed

  • Any severe environment calls for IEEE 841. Cases 3 and 7 are severe but do not name IEEE 841, so the answer is SD; the feedback states the rule.
  • A dusty or dirty environment is automatically a hazardous location. Only the cases with an owner's NEC classification (4 and 6) are DFG.
  • General duty is acceptable anywhere the motor has a TEFC enclosure. The mining case names a TEFC motor and still needs IEEE 841; GD fits only clean, cool air.

Assessment

  • First-attempt score shown in the summary as "First-attempt score: n of 8"; mastery is 7 of 8 on the first attempt. The running line reads "Correct: n of 8".
  • Follow-up question: a refinery inquiry describes oil mist around the motor and the plant's motor standard calls for IEEE 841. A second inquiry from the same refinery is for a fan in an area the owner classifies Class I, Division 2, Group D. Which duty goes on each motor line?

References

  1. FanPedia: The Fan & Blower Encyclopedia (PDF) - Twin City Fan & Blower; p. 73 (Motor Specifications: intended duty and enclosure) and p. 71 (the example motor line).
  2. FanPedia online - Twin City Fan & Blower's online version of the encyclopedia.
  3. Chapter 15: Motor Ratings, Speed Control and Positioners - the sections "Motor Intended Duty", "Severe Duty Motor" and "Hazardous Location Motor".
  4. Electrical equipment in hazardous areas (Wikipedia) - background on NEC classes, divisions and groups.