An employee asked to-day "Why is the UK on 50Hz Frequency" I'm afraid i could not answer him but i did promise to find out.

There was a long thread about this in the uk.d-i-y about a year ago. I have taken some info from these posting. (I noticed that both I and Sven had been active in this thread, btw )

By Colin Bignell:

By about 1930, the majority of domestic supplies were around 200-250 volts,
although there were plenty of other voltages around. IIRC, the lowest was 12
volts and the highest *domestic* supply was about 400v. A goodly number of
supplies were DC and the AC frequencies, although mostly 40Hz or 50Hz,
varied from 25Hz to 100Hz. You could also have one- two- or three-phase
supplies. So long as each electricity undertaking produced its own
electricity, none of this was a problem. When the national grid came along,
somebody had to decide on national standards. 240v, with tolerances that
allowed local variations between 220v and 250v (much like our recent
'change-over' to 230v) happened to be compatible with significantly more
existing supplies than anything else.

Certainly it is most probable that the reason that 240V 50HZ was finally
adopted is one of economics. In 1925, there were over 650 power stations in
Britain and London alone had 10 different frequencies and 20 different
voltages. However, just 28 power stations generated 50% of the electricity
in Britain. These were the most economic stations to run and they almost
exclusively supplied 415V / 240V systems. NE England had adopted 40Hz and
had one of the best organised electricity supply undertakings - it passed
into nationalisation almost untouched as the NEEB. Unfortunately for them,
81% of all plant working in 1930 used 50Hz and that dictated its adoption
for the national grid.

Many people preferred DC for lighting. Very early AC systems worked at
fairly low frequencies - 25Hz was common and some were even lower. Many
people could detect flicker in lights at these frequencies, which using DC
avoided. One domestic lighting supply of the period was 12v DC and worked by
charging lead-acid accumulators in the consumer's house, which then ran the
lights.


[This message has been edited by C-H (edited 01-20-2003).]

Why did so much power come from 50Hz power plants? AEG in Germany had adopted this frequncy and countries like Sweden followed suit. This probably meant that you could buy 50Hz equipment in Europe at a lower cost than 40 or 25Hz equipment. Unlike consumer goods, the market for large industrial equipment, like turbines and generators, has always been international. If you were going to spend millions of pounds, the potential savings outweighed the extra work of dealing with foreign companies.

[This message has been edited by C-H (edited 01-20-2003).]

Thanks for the info, i will pass this on to-morrow. Hopefully it will answer his question. Just for your information the employee is studying for his ONC in Electrical Electronic Engineering in the UK

That's an excellent piece that C-H has clipped and posted. There are a lot of standards around today which exist for various historical reasons.

50Hz power was also used in America in the past. Bjarney sent me a short article on the changeover from 50 to 60Hz power in Los Angeles in 1936.

Scott,
I didn't keep a copy on disk -- Maybe you could forward a copy of that article to anyone interested?

OT, but here's some “Gotta Have It” electrical advertising…
http://scriptorium.lib.duke.edu/eaa/ephemera/A05/A0504/A0504-02-72dpi.html