IEEE Power & Energy Magazine - January/February 2018 - 56

history

Robert D. Barnett

arc lighting systems
the first electrical distribution systems

From about 1885 to 1915, the
most common means of lighting streets
was the use of arc lamps. these lamps
and the systems by which they were
supplied power were very technologically sophisticated. these were the first
electrical distribution systems. the
manufacturing companies that made
the equipment for arc lighting went on
to be the companies that launched the
so-called electrical age.
to appreciate how soph ist icated
these devices actually were, we need
to understand how they functioned.
We'll begin by classifying arc lighting
systems as dc, also known as continuous current at that time (not the same as
constant current), ac, series-connected
constant current, parallel-connected
constant potential, and open arc or enclosed arc. table 1 shows the types of
arc lamp systems that were available at
the beginning of the 1890s.
a constant potential system is what is
now used in almost every case for lighting
and power. the voltage is held constant,
and the current changes as load is added
or removed. this was not always the case.
beginning in the mid-1880s, the series,
dc, constant current system came into
widespread use to provide arc lamps for
street lighting. this system was supplied
from special dc generators that were controlled to keep the current flowing to the
lamps as close to a constant amperage as
possible. We'll concentrate on these types

Digital Object Identifier 10.1109/MPE.2017.2759920
Date of publication: 5 January 2018

ieee power & energy magazine

The most visible (ahem) early use of electric power changed forever the face and
life of our cities. In this delightful column, Robert Barnett describes the technology, which was remarkably sophisticated. Bob insists he is a technologist, not a
historian. "It's a technology article that just happens to be about old stuff," he
said. But in 1982, he formed the Niagara Society for Industrial History as a support group for a proposed museum in a former Niagara Falls power plant, and
he has written a lot of history. A Senior Member of the IEEE, he graduated from
the University of Waterloo and Niagara College. He supports his technology/history interest as an industrial control and power designer. He is a senior electrical
engineer with Cascades Containerboard Packaging Inc.
Hyde Merrill
Associate Editor, History

of lamps and mention the other systems
only as they differ from this type.

Arc Lamps
First, let's begin by examining the source
of the light-the arc itself. We'll describe
the arc produced in a dc constant current lamp. the arcs produced in the other
types of lamps are very similar.
Figure 1 shows two rods or electrodes connected to the supply circuit
with the upper electrode at a positive
potential with respect to the lower electrode. the D inside the circle stands for

dynamo or generator. the lines connected to the circle's circumference at
an angle are meant to represent brushes
that allow current to flow from the rotating part of the generator to the stationary circuit conductors. the details
of this are beyond the scope of this article. For our purposes, you can think
of the generator as a battery.
the potential difference (voltage)
between these two electrodes is chosen
sufficiently high that when the lamp
is started and the electrodes begin to
open, an arc is drawn between them.

table 1. Arc lighting systems.
Continuous Current (dc)

Alternating Current (ac)

Constant Current

Constant Potential

Constant Current

Constant Potential

Open

Enclosed

january/february 2018

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - January/February 2018