when or did they convert to a 60hz service at your house/far

Jim

OH, you might be surprised to learn that DC has been used for many years for long distance power transmission. The losses are actually lower with high voltage DC than they would be for AC at the same voltage. The downside is the cost to convert ac to dc and back to ac, which is why DC is only used over long distances (several hundred miles).

Gerald j.

• Some power frequency history.

The old rotating freq at Safe Harbor has recently been given a new lease on life. Not sure, but I think that Metuchen is already gone though.

A lot of power systems, especially those in urban settings often have 100 times the short circuit current (and hence really low source impedance) than they had 25 or 30 years ago. Which leads to 100K amp fault currents in 240 volt panels which means the panel has to be made a whole lot sturdier than the old 15K amp fault current main panels.

Any article is dated by the time its converted from notes to print or the internet and power systems are always changing whether the owners want to or not.

Likely the scrap prices for the copper and iron of the trashed rotary converter almost paid for the solid state converter which gives higher efficiency and easier repair.

Gerald J.

But that is a good thing because it helps me make a living.

I'd not be really surprised if some of the solid state converters weren't bidirectional as the power company hasn't been a fan of customers pushing power back into the system because the power plant controls aren't always adapted to that and such back feeds make the power system unstable (flashing and blinking lights).

Gerald J.

I don't know if the static converters can go to 60 or not. I doubt that they would want them too, at least not for very long. It would be uneconomical most of the time. And static converters can't seem to handle much reactive load either, which is no problem for the old rotating equipment. We are on a lot for voltage support.

The most common “house” radio of the late 40’s and 50’s was the AC/DC superhetrodine. It would operate on either power source but you might need to turn the plug connection over on DC to get the polarity right so that the current would flow from the ELEMENT to the PLATE in the tubes. Superhetrodine, meant that the received RF was mixed with an internally generated RF signal so that a differential signal, (usually 455KC) was generated. There were two or more stages of frequency tuned amplifiers to boost this signal, only then was the audio detection done and amplified for the speaker.

Where solid-state amplifiers are primarily current boosters, the tube-type amplification was a voltage device and would not boost power at the 6 or 12 volts provided by car electrical systems, they had a “vibrator” that chopped that low voltage into a square wave of a frequency high enough to feed the primary of a voltage step-up transformer which was filtered at the seconary and provided to the PLATES of the amplifier tubes at a DC voltage that could range in the low hundreds.

SMALL 60 CYCLE VARIANCE
I was a municipal power plant operator at a small town diesel-electric plant, 800KWH maximum. There was no electronic reference to keep the plant running at 60 cycles. I am not sure if there were even mechanical governors, the plants frequency output varied as the load went up and down. Anyway if the operator was sloppy the electric clocks could gain or loose several minuets during an eight hour shift. Eventually an operator would speed up or slow down the frequency to get the clocks on the system back on time. I am sure that the output of the plant was often 1˝ to 2 cycles, plus or minus 60. The phone would have been ringing if television was affected and the phone did not ring. This was in the mid 1960’s. My impression was the some early TVs referenced the power signal but later generated there own synchronous signal.

Southern California changed, but I'm not sure when.

Gerald J.

Transformers are designed for a minimum frequency and give the same performance up to a few KHz though the core loss changes with frequency. At the low end the core loss falls as the induduced magnetic field falls due to the higher reactance of the windings, but at higher frequencies, the core loss rises because of edy currents in the core laminations.

So a 25 Hz transformer works fine on 60 Hz and even higher and so does the radio. I've designed transformers so I know how they work.

25 Hz and lower frequencies work better on the series traction motors, less sparking at the brushes.

There were many clocks that weren't self starting, a very simple synchronous motor was used. And it would run equally well backwards. A bit of shading on the pole pieces (copper band around part of the pole) will make them start in the right direction, but even then some timer motors I've had apart have a pall that catches in the gears if the motor starts backwards and the bounce off that gets them running fowards. Synchronous motors are very sensitive to power frequency and such clocks make a good test instrument for setting the portable generator.

Gerald J.

Gerald J.