The origins of 60-Hz as a power frequency (1997)

Original Article ↗ Hacker News Discussion ↗

Historical origins and legacy frequencies

  • Summary of paper as discussed: early systems experimented with ~130 Hz (resonance, motor issues) and ~25–30 Hz (severe light flicker).
  • 50–60 Hz emerged as a compromise between motor performance and lighting.
  • Westinghouse pushed 60 Hz (better for flicker) and won the US market over GE’s 50 Hz, which aligned with its European affiliate that had moved from 40 to 50 Hz.
  • Niagra Falls and rail systems used 25 Hz; parts of Amtrak and Ontario industry ran on 25 Hz well into recent decades. Central European rail still uses ~16.7 Hz for traction.

Modern relevance of mains frequency

  • Several argue that for most consumers, frequency is now “implementation detail”: electronics use SMPS, many motors are variable-speed or EC, and motor clocks are rare.
  • Others note frequency still affects certain motors (fans, dryers, some industrial loads) and especially transformers: 60 Hz transformers may overheat at 50 Hz; 50 Hz designs must be physically larger.

Grid behavior, timing, and clocks

  • Classic mains-synchronous clocks rely on long-term average frequency; grids are deliberately corrected so that daily average is exact (e.g., 60 Hz in US).
  • Frequency drifts with supply–demand imbalance; deviations are used as a control signal for generators.
  • Example: the European grid once accumulated a 6‑minute deficit due to a regional dispute, later corrected.
  • Recorded mains hum can be correlated with logged frequency to timestamp audio/video forensically.

Regional grid differences and interconnection

  • Japan famously has both 50 and 60 Hz regions due to historical generator purchases, complicating power sharing; some speculate this fostered early inverter development.
  • North America has multiple synchronous “interconnections” (East, West, Texas, others) joined mostly by HVDC or variable-frequency ties.
  • Rail and other special systems use their own frequencies with rotary or electronic converters.

Hypothetical optimal frequency/voltage

  • No consensus: trade-offs between transmission loss (favoring low frequency or DC, high voltage), transformer/motor size (favoring higher frequency), safety, and converter cost.
  • Strong thread arguing “0 Hz” (HVDC) is best for long-distance transmission given modern power electronics, but AC remains simple and robust to transform.
  • Some propose mixed systems: HVDC long-distance, then AC or low-voltage DC locally; others emphasize that multiple voltages/frequencies add complexity.

Voltage levels, wiring, and appliances

  • 240 V allows more power on typical household circuit currents than 120 V, enabling faster kettles/toasters; equivalent power at 120 V requires higher current and thicker copper.
  • Several detailed exchanges on I²R losses, wire gauge, copper vs aluminum, and why higher voltage transmission is cheaper but more dangerous.
  • Debate over safety statistics: some claim lower nominal US voltage reduces electrocution risk; others question comparability of data and note many deaths are from non-outlet sources.

Frequency in devices and signals

  • 60 Hz influenced:
    • Synchronous clocks (gear ratios align with 60 s/min).
    • Early TV frame rates and regional video standards.
    • Common motor speeds, which then influenced HDD RPMs (3600, 5400, 7200 rpm).
  • Anecdotes about audible hum around B0 (~61.7 Hz) from power systems.
  • Some mathematical niceties: 60 as highly composite; 2π·60 ≈ 377 rad/s, close to free-space impedance in ohms—seen as a neat but likely coincidental convenience.

Practical annoyances and path dependence

  • Travelers and movers complain about incompatible appliances despite “universal” power supplies; heavy or motorized gear, clippers, and some kitchen equipment still care about frequency.
  • LED flicker (lighting, car taillights) is now more tied to PWM design than mains frequency, but users find low PWM rates distracting, especially in peripheral vision or during eye movements.
  • Multiple commenters note that with modern wide‑range switchmode supplies, most small electronics are now agnostic to 50 vs 60 Hz and local voltage, even though legacy choices continue to ripple through infrastructure and some appliance categories.