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Motor Line Decoder

Run the Motor Line Decoder MicroSim Fullscreen

About This MicroSim

A Twin City Fan order describes the motor in one coded line (FanPedia p. 71):

50 HP, 1800 RPM, IN, P, 3 Phase, 60 Frequency, 460 Volt, SD, TEFC, 326T

This MicroSim shows the whole line with one field highlighted at a time. For each of the ten fields you pick one of four meanings before anything is revealed; the four choices appear in a fixed shuffled order. Each field has one scored pick. After the pick:

  • the correct meaning is marked ✓ (solid green) and a wrong pick ✗ (dashed red);
  • the feedback reads "✓ Correct:" or "✗ Not quite:" followed by the field's explanation, and for five common slips a one-line note (for example, "Phase appears later as 3 Phase; P here is efficiency.");
  • a short decoded meaning stays visible under that field of the line.

The running count reads "First-try correct: n of 10". After field 10 the whole line is shown decoded with the first-try score and whether mastery (8 of 10 on the first try) was reached. Any answered field in the line can be selected to reread its explanation; that is exploration and never changes the score.

Field Meaning Why
50 HP Rated power 50 horsepower About 37 kW using kW = HP × 0.7457
1800 RPM Synchronous speed of a 4-pole 60 Hz motor 120 × 60 / 4 = 1800; the motor runs slightly slower because of slip
IN Induction technology The alternative is EC (electronically commutated)
P Premium Efficiency Comparable to NEMA Premium and IEC IE3
3 Phase Three-phase AC supply Electric power field: phase
60 Frequency 60 Hz supply frequency Electric power field: frequency
460 Volt 460 V supply voltage Electric power field: voltage
SD Severe Duty GD is general duty; DFG is explosion proof
TEFC Totally enclosed fan cooled Sealed windings; an external fan blows air over the frame
326T NEMA 326 frame, T-frame foot mount Shaft height 32/4 = 8 inches from the bottom of the feet

The distractor meanings are illustrative and are not real codes.

How to Use

  1. Read the highlighted field (▸) in the motor line and the question below it.
  2. Pick a meaning (click it or press 1–4). Read the explanation and see the correct meaning marked.
  3. Press Next field (or Enter). After field 10, press Show decoded line to see the whole line decoded with your score.
  4. Select any answered field in the line to reread its explanation. Press Start over to clear the score and begin again at field 1.

Keyboard: 1–4 pick a meaning; Enter goes to the next field. Tab reaches the meanings, the answered fields of the line and the buttons; Enter or Space presses a focused button.

Data label: "Source: FanPedia pp. 71–74 (motor line and field meanings) · distractor meanings are illustrative, not real codes", shown under the motor line.

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/ch14-motor-line-decoder/main.html"
        height="662px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Learning Objective

The learner will interpret each of the ten fields of a Twin City Fan motor specification line, choosing the correct meaning for at least 8 of 10 fields on the first attempt (Bloom: Understand, verb: interpret).

Audience

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

Duration

10 minutes

Prerequisites

  • Horsepower, synchronous speed and poles
  • Induction and EC motor technology
  • Efficiency class; phase, frequency and voltage
  • Intended duty and motor enclosure
  • NEMA frame size and frame letters, from Chapter 14

Activities

  1. Predict (6 min): For each field, say the meaning aloud before picking, then compare with the explanation.
  2. Review (2 min): Select the fields you missed in the decoded line and reread their explanations.
  3. Transfer (2 min): Rewrite the line for a 25 HP, 1200 RPM, EC, Standard Efficiency, single-phase 230 V general-duty ODP motor, and check each field against the chapter's table.

Common Misconceptions Addressed

  • "1800 RPM" is the exact running speed: field 2 explains synchronous speed and slip.
  • "P" means phase: field 4 notes that phase appears later as 3 Phase.
  • "SD" means standard duty: field 8 notes that general duty is GD.
  • "T" in 326T means TEFC: field 10 notes that T marks the T-frame foot mount.
  • "60 Frequency" is a speed: field 6 notes that it is the supply's 60 cycles per second.

Assessment

  • First-try score shown as "First-try correct: n of 10"; mastery is 8 of 10 on the first attempt.
  • Follow-up: what is the shaft height of a 184T motor, and how do you know?

References

  1. Twin City Fan & Blower. FanPedia: The Fan & Blower Encyclopedia, p. 71 (typical motor specifications), p. 72 (efficiency), p. 73 (enclosure and intended duty), p. 74 (frame sizes and letters). PDF
  2. Twin City Fan & Blower. FanPedia online - the online edition of the same reference.
  3. NEMA. ANSI/NEMA MG 1, Motors and Generators - frame designations, synchronous speeds and service factor. NEMA