Street Light Controls

[5wp]

Looking for historical information on street light controls.
I'm interested in knowing how street lights were controlled
in the 1950's and 60's. What was used before the photocell,
or has it been around from the beginning? If mechanical
timers were used did they need to be reset for varying hours
of sunlight, ie. northern climates?

 

[waross]

Astronomical time clocks have been around for a long time.

http://www.intermatic.com/products/timers/mechanical time switches/astronomic.aspx

An excerpt from here:

http://www.paragontimecontrols.com/index.html

Established in 1903, Paragon sold electrical and telephone specialties, then began manufacturing hand-wound time switches. Power companies purchased time switches to control generators. Cities used them to control street lights. Electrical signs with time switches became popular. As demand for time switches grew, so did Paragon. Prior to the Depression, Paragon introduced an electrically-driven time switch. The country rebounded, and in 1932, Paragon developed the first synchronous motor time switch controlled with the accuracy and convenience of an electrical clock.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[VEBill]

Photocells have been around for a very long time (certainly before the 1950s and 1960s). I recall that CdS photocells were considered to be a bit "old-school" by the late 60s.

The rest of a traditional street light switch is electromechanical (thermal switch).

 

[5wp]

Thanks guys for the comeback and info.

 

[waross]

In the mid 60's a common light control photo-cell would be a photo resistor in series with a heater element heating a bi-metal strip. The lamp would come on when the circuit was first energized. If there was enough light incident on the photo resistor the heater would heat the bi-metal strip sufficiently to open the lamp circuit.
Older photocells used for such things as conveyor control often had a vacuum tube light detector and a vacuum tube amplifier contained in one case.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[rasevskii]

In the USA street lighting was traditionally a series circuit
running at a constant current of 6.6 A and variable voltage supplied at the substation. Many lamps in series with a drop of several volts across each lamp. If a lamp burned out, the resulting open-circuit voltage across that lamp burned through a small mica button in the socket re-establishing the circuit.

The supply was from a 2300 or 4000 volt bus via a series regulator, a mechanical contraption involving moving and stationary coils which regulated the current. A solid state magnetic regulator was also used. The circuit was usually manually switched on by an oil switch by the substation operator, or a clock.

With the advent of modern mercury vapor and flourescent street lighting the series systems fell out of favor. Very likely no longer used anywhere.

rasevskii

 

[waross]

As well as 6.6A there were 7.2A, 7.5A and 20 Amp circuits.
20 Amps was favored for lamps near street car tracks. The filaments were very heavy and were better able to withstand the vibration of passing street cars.
There were current transformers to change from one system to another. eg: 7.5 Amps to 6.6 Amps.
Some circuits used mercury vapor lamps with ballasts designed for series operation.
Series circuits are still use for airport runway lighting.
Some of the old series regulators were adjusted by adding or removing iron balance weights.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[5wp]

Thanks again for that added info.

 

[sonewone]

We generally use the photo controls from

http://www.ripleylightingcontrols.com/

I am looking for any others with smaller foot print. Can any one suggest aternative?

Thanks

 

[jraef]

This looks like a homework question, is it?


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[sonewone]

Nope it isn't
I have tried to look up, but in vain.

If some one has used an alternative (Preferably with a smaller foot print), I wish they could share it here.

 

[waross]

This is the smallest one that I have seen, but you already have this link.

http://www.ripleylightingcontrols.com/wire-in/700x.html

Bill
--------------------
"Why not the best?"
Jimmy Carter