Comments on: AC power frequencies

By: Tomi Engdahl

Tomi Engdahl — Sat, 01 Aug 2026 19:22:13 +0000

400 Hz transformers use ultra-thin laminations (e.g., 0.1 mm to 0.2 mm vs. 0.35 mm for 50 Hz), special nickel-iron alloys, or cobalt-iron cores to keep the high-frequency losses low while maximizing B_{\max}.

By: Tomi Engdahl

Tomi Engdahl — Sat, 01 Aug 2026 19:12:42 +0000

In an aircraft, weight reduction has a high priority. Inductive components such as motors and transformers require far less iron core material and copper wire for the windings at 400Hz, as opposed to 50Hz. Taking this even further, the reasons why the transformers inside powerful mobile phone chargers, for example, operate at typical frequencies in the 100kHz range, reducing the size down to practically nothing.

By: Tomi Engdahl

Tomi Engdahl — Sat, 01 Aug 2026 19:10:19 +0000

Why 400 Hz in aviation?
Short answer: Weight savings

Airplanes use 400 Hz instead of 50/60 Hz for one main reason: smaller, lighter equipment.

Why 400 Hz is better for planes?

1. Transformers and motors get away smaller
The size of transformers, motors, and other electrical parts depends on frequency.

At 400 Hz, the magnetic core in a transformer can be 6-8x smaller than at 50 Hz to do the same job.
On a plane, every kg matters. Saving 100kg in wiring + generators = more passengers/cargo + less fuel.

2. Smoother power for motors
400 Hz makes aircraft motors run smoother with less vibration. That’s good for fuel pumps, cabin fans, and hydraulics.

3. It’s been the standard since the 1950s
Military aircraft started, then commercial jets like the Boeing 707 adopted it. Now it’s the global aviation standard: 115V AC, 400Hz, 3-phase.

The trade-offs
400 Hz is _terrible_ for long-distance transmission. It has more losses and heat.
That’s why to use 50 Hz in Zambia and 60 Hz in the US on the ground – it’s better for sending power across cities.

But inside a plane, wires are only a few meters long, so losses don’t matter. Weight does.

By: Tomi Engdahl

Tomi Engdahl — Sat, 01 Aug 2026 06:01:11 +0000

Aviation are utilizing a much higher frequency, typically 400 Hz. The engineering needs of an aircraft are completely different from those of a ground-based railway network. The choice of frequency comes down to a fundamental tradeoff between equipment weight and transmission distance. For transformers, motors, and generators, higher frequencies mean that less magnetic core material and fewer copper coils are required to transfer the same amount of power. This allows components to be significantly smaller and lighter, which is critical for flight.

By: Tomi Engdahl

Tomi Engdahl — Sat, 01 Aug 2026 05:58:40 +0000

16.7 Hz power is a specialized low-frequency alternating current (AC) electrical system used primarily for railway traction power in countries like Germany, Austria, Switzerland, Sweden, and Norway.

German railways have run for years on 15kV 16⅔ Hz. They seem to manage.

By: Tomi Engdahl

Tomi Engdahl — Sun, 19 Jul 2026 15:11:37 +0000

This claim turns the actual physics of transformers completely upside down. While it is true that a 230V/400V} grid is much cheaper to build and operate than a 120V grid, the commenter’s reasoning about frequency (Hz) and iron is factually backward.
The claim states that 50Hz allowed Europe to use “far far less iron in their transformers” is wrong: lower frequencies require larger iron cores. A 50Hz transformer requires roughly 20% more iron core volume than an identical capacity 60Hz transformer to prevent the iron from magnetically saturating.
European system is cheaper to construct, but the savings are entirely in copper (and aluminum) due to the higher voltage (230V phase-to-neutral / 400V phase-to-phase).
Why 50Hz? In Germany, AEG engineer Mikhail Dolivo-Dobrovolsky developed the first practical three-phase system. He chose 50Hz because it was high enough to keep incandescent light bulbs from visibly flickering, but low enough to minimize inductive losses in long transmission lines given the engineering limits of 1891.
Why 60Hz? Across the Atlantic, Nikola Tesla and Westinghouse independently arrived at 60Hz as the optimal sweet spot for their specific arc lighting systems and induction motors.

By: Tomi Engdahl

Tomi Engdahl — Sat, 07 Feb 2026 20:31:32 +0000

Difference Between 50 Hz and 60 Hz Frequency System
https://www.electricaltechnology.org/2023/03/difference-between-50-hz-and-60-hz-frequency.html#google_vignette

By: wordle unlimited

wordle unlimited — Wed, 10 Sep 2025 08:10:50 +0000

I used to 220v

By: Tomi Engdahl

Tomi Engdahl — Wed, 06 Mar 2024 11:41:17 +0000

60Hz/230V is the norm in cruise ships

60hz 220v and quite possibly IT-grounding is pretty much standard.