Technical reference
32 articles
PCB Trace Width & Current Capacity: What IPC-2221 Actually Says
Where the IPC-2221 current-capacity curve fit comes from, what it assumes, and how it differs from IPC-2152.
Creepage & Clearance: How IEC 60664-1 Sets Insulation Distances
Creepage vs clearance, and how pollution degree, CTI, working voltage and altitude drive IEC 60664-1 distances.
Bolt Preload & Torque: How VDI 2230 Models a Bolted Joint
The cone-of-compression stiffness model and the T = K·F·d torque-preload relationship behind VDI 2230.
EV Cable Sizing: What ISO 6722 Says About Ampacity
How ISO 6722 temperature classes set EV cable ampacity, why it comes from a heat balance, and how bundling derates it.
DC-Link Capacitor Ripple: The Kolar & Round Method
The Kolar & Round ripple-current formula for a three-phase inverter, why it peaks near M≈0.6, and what sizes the cap.
O-Ring Gland Design: Squeeze, Stretch & Fill to AS568 / ISO 3601
Squeeze, stretch and gland fill explained, plus the AS568 / ISO 3601 size system and the limits that keep a seal working.
Busbar Heating: Ampacity to IEC 60287 and Faults to IEC 60865-1
Continuous ampacity from an I²R heat balance (IEC 60287 skin effect) and adiabatic short-circuit heating per IEC 60865-1.
Interference Fits: ISO 286 Tolerances and Lamé Stresses
How ISO 286 fits set the interference and Lamé thick-cylinder theory turns it into contact pressure, stress and insertion force.
Mohr's Circle & Plane-Stress Transformation, Explained
Plane-stress transformation and the Mohr's-circle construction: principal stresses, max shear, and von Mises / Tresca.
Skin Depth & Skin Effect: Why AC Current Crowds the Surface
Why AC current crowds a conductor's surface, the skin-depth formula, and why it depends on material and frequency, not size.
Common-Mode & Differential-Mode Choke Sizing, Explained
CM vs DM chokes, how core geometry sets inductance, and the saturation and Steinmetz core-loss limits that size them.
SiC Inverter Losses: Conduction, Switching & Reverse Recovery
Where a SiC inverter's losses go — conduction, switching, reverse recovery — and how they set junction temperature.
Id/Iq & Field-Oriented Control: The Park Transform and MTPA
What the Clarke/Park transform does, how Id/Iq split PMSM torque into magnet and reluctance terms, and how MTPA works.
Motor Winding AC Copper Loss: Skin Effect, Proximity Effect and Dowell's Equation
Why a winding's AC resistance exceeds its DC value, how Dowell's equation captures skin and proximity effect together, and why round, hairpin and litz wire behave so differently.
Parallel Path Circulating Current: Why Untransposed Strands Fight Each Other
Why parallel strands at different slot depths fight each other with a circulating current, and why transposition — the classical fix — cancels it.
Battery Cell Cooling: Why Distributed Heat Generation Changes the Math
Why a cell's distributed heat generation changes the conduction math, and why cylindrical, prismatic, and pouch cells each have a natural cooling face.
Bolt Pattern Analysis: The Elastic Method for Bolt Groups
The elastic method for eccentrically-loaded bolt groups: direct + torsional shear, moment-driven tension, and its limits.
Beam Bending: Euler–Bernoulli Theory and Roark's Formulas
What Euler–Bernoulli theory assumes, the shear→moment→deflection chain, and determinate vs indeterminate beams.
Torque, Power & Speed: The P = T·ω Relationship
Why P = T·ω holds for any rotating shaft, the unit traps, and how motor torque relates to current.
Battery Pack Configuration: What S×P Does to a Cell
How series adds voltage, parallel adds capacity, how internal resistance combines, and what S×P means for voltage sag.
Wire Bundle Diameter: Circle Packing and the Glenair Method
The two ways to estimate harness bundle diameter — circle packing and the Glenair factor table — and what coverings add.
Heat Exchanger Sizing: The Effectiveness-NTU Method
What UA, NTU, Cmin and Cr mean, the crossflow-both-unmixed effectiveness formula, and what really limits a core's heat rejection.
Cold Plate Design: Rectangular-Channel Heat Transfer and Pressure Drop
Why a rectangular channel isn't a round pipe, how Shah-London sets the heat-transfer coefficient and friction, and how it all becomes a base temperature.
Pipe Pressure Drop & Pump Sizing: Darcy-Weisbach and the Friction Factor
How Darcy-Weisbach turns flow, pipe size and roughness into a pressure drop, and how that becomes the pump head and power you need to specify.
Heatsink Sizing: Junction-to-Ambient Rth and Natural-Convection Fin Arrays
How the Rjc+Rcs+Rsa chain sets the sink budget, and how Churchill-Chu convection and fin efficiency size a natural-convection fin array.
EMC Shielding Effectiveness: How Schelkunoff's SE = A + R + B Works
How absorption and reflection loss combine into SE = A + R + B, and why near-field sources need a different reflection-loss formula than a far-field plane wave.
Apertures & Vent Panels: Why Openings Set Your Real EMC Shielding
Why a slot radiates like an antenna above half a wavelength, and how waveguide-below-cutoff theory lets a vent panel breathe while still blocking RF.
Enclosure Cavity Resonance: When a Shield Becomes an Antenna
Why a shielded enclosure has resonant frequencies of its own, and why shielding effectiveness can collapse at those specific frequencies regardless of barrier material.
Grounding Strap Inductance: Why Impedance, Not Resistance, Rules RF Bonding
Why impedance, not DC resistance, governs a grounding or bonding connection at RF — and why a wide flat strap always beats a round-wire pigtail of the same length.
MIL-DTL-38999 Connectors: Contact Sizes, Ratings & Pinouts
What MIL-DTL-38999 covers, how contact size sets current rating, and how a point-to-point harness pinout is laid out.
Bearing Life & Selection: How ISO 281 Rates a Rolling Bearing
Where the L10 = (C/P)^p rating-life formula comes from, the equivalent load P = X·Fr + Y·Fa, and the static and lubrication limits.
Involute Splines: Geometry, Measurement Over Pins & Torque Capacity
How module and pressure angle set involute-spline geometry, how measurement over pins works, and how splines are rated for torque.