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The Huntsville Engineering Brief · Issue #2

Electrical Tuesday

Tuesday, August 4, 2026

Three numbers that explain why your utility bill is what it is — and why industrial plants get billed differently.

Term 1: Impedance

Electrical

Total opposition to current flow in an AC circuit. Resistance is one component (R). The other (X) comes from capacitors and inductors storing and releasing energy out of phase with the voltage. Add them as a complex number; the magnitude is what limits current; the phase angle is what creates power factor problems.

Z = R + jX

Why it matters: Every signal-integrity headache in a test fixture — line drop, crosstalk, mismatched terminations — traces back to impedance mismatch somewhere in the chain.

Term 2: Reactance

Electrical

The opposition to current change from capacitors and inductors. Inductive reactance grows with frequency. Capacitive reactance shrinks with frequency. At one specific frequency the two cancel; that's resonance. Tune a circuit by picking values that put the resonance where you want it.

X_L = 2πfL · X_C = 1/(2πfC)

Why it matters: Filters, antennas, and motor-drive controllers all live or die on whether reactance is doing the right thing at the right frequency.

Term 3: Power Factor

Electrical

Ratio of real power (the watts that do useful work) to apparent power (the volt-amps the source actually delivers). A power factor of 1.0 is ideal — voltage and current in phase. Industrial loads with lots of motors run 0.7 to 0.95. Utilities surcharge industrial customers whose power factor is too low.

PF = P / S = cos(φ)

Why it matters: Power factor correction capacitors are why every mid-size plant in North Alabama has a bank of caps near the main switchgear — and why the plant engineer who manages them quietly saves the company tens of thousands a year.

📍 Huntsville Pulse

⚙ Engineering joke of the day

Why don't electrical engineers go camping? Too much resistance and not enough capacitance for the load.

Issue #2 · The Huntsville Engineering Brief

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