megawatts by microwave

In 1914 the Department of the Interior, through the Bureau of Reclamation,
investigated the possibilities of developing the Columbia River. Thousands of
arid but potentially fertile acres needed only water to become the Imperial
Valley of the Northwest. Locked in the mountain ranges were valuable ores
awaiting electricity to turn them into needed metals.

Two years later the State engineer of Oregon urged the development of the
Bonneville site as a national-defense measure: he saw in the proposed power
project a source of fertilizer in time of peace and nitrates in time of war.
The dam also would completely drown out the Cascade Rapids and extend
slack-water navigation some 40 miles eastward to The Dalles.

The Rivers and Harbors Act of 1925 directed the Secretary of War, through the
Corps of Engineers, United States Army, to prepare and submit to the Congress
an estimate of the cost of surveys, examinations, and investigations of all
navigable streams and their tributaries where power development appeared
feasible. (Q1)

It is difficult to succinctly explain why, exactly, the United States Army has
spent much of its history involved in the construction of dams. It is partly an
accident of history, partly the result of interagency federal politics, and
entirely a product of American culture. In his book “Cadillac Desert,” Marc
Reisner examines the history of the American West’s water control projects
as a religious project, one animated less by practical needs than by a sense
that domination of the West’s rivers was destiny.

The Bureau of Reclamation, part of the Department of the Interior, was formed
for that purpose. At the time, though, the Army had already been used to survey
and improve rivers for nearly 100 years. They were not content to give it up. The
result was a rivalry, one with several feints and blows before the two settled
into their modern areas of control. For the Bureau of Reclamation, the Hoover
Dam was their signature project. For the Corps of Engineers, the battle that
would go down in history was the Columbia River Project.

The motivations for damming the Columbia were various. The Columbia was prone to
flooding, which had caused damage and limited use of land along it. There was a
great deal of land surrounding the Columbia that could be farmed, if the
Columbia could be tapped for irrigation. Electricity, too, was a reason,
although initially a somewhat secondary one. Perhaps the greatest reason,
though, was simply economic: by the time that the major parts of the Columbia
River Project were truly underway, the nation was in the throes of the Great
Depression.

President Franklin D. Roosevelt was already a fan of hydroelectricity. As
governor of New York, he was exposed to the pioneering Niagara Falls power plant
and pushed for other similar projects in that state. As President, his “New
Deal” naturally incorporated hydropower as well. By 1934, he had formed a
Regional Planning Commission that sketched out a series of dams along the
Columbia, two of which would become the Grand Coulee and the Bonneville. These
dams would produce a tremendous amount of electricity, and unlike in other
similar Corps of Engineers projects to date, that power would not all be
consumed by irrigation pumping. There was power to spare. To distribute that
power, the Regional Planning Commission suggested an independent government
agency on the model of the Panama Canal or the recently chartered Tennessee
Valley Authority.

As an interim measure, the loosely defined Bonneville Project coordinated the
civilian side of the Corps of Engineers project until 1938, when the Bonneville
Dam was complete and the Grand Coulee was much of the way there. The Bonneville
Dam captures little water in its reservoir, so while it does have flood control
value, electrical production is its primary purpose. The dam’s two powerhouses
produce up to 1.2 GW, an impressive number for the 1930s but one that pales in
comparison to the Grand Coulee’s eventual (1970s) full capacity of nearly 7 GW.
The Columbia River dams increased the electrical capacity of the Pacific
Northwest by orders of magnitude; the numbers were significant even at a
nationwide scale.

The bumper crop of electricity triggered a predictable controversy: what to do
with government power? One camp favored public control of the resource, with the
government marketing the power on some sort of equitable basis. The other
favored private control, arguing that the output of the dams should be
contracted entirely to private utilities like Portland General Electric (itself
the scion of an important early hydroelectric project at Willamette Falls). In
the New Deal political climate, the first camp won: the Columbia did not quite
get a TVA, but Congress did charter the Bonneville Power Administration (BPA),
the first of what would come to be known as Power Marketing Agencies. Over the
following decades, the BPA became part of the Department of Energy
(DoE)—uncharacteristically, for the DoE, a part of it that actually generated
and sold electricity. Well, technically, the Corps of Engineers generates it,
and the BPA markets and distributes it.

In any case, starting in the late 1930s, the BPA was tasked with the
construction of a network that could distribute power from Columbia River dams
throughout the region—on an equitable, equal-rate basis often called the
“postage stamp rate” that allowed rural coops to buy government-generated power
at the same rate as the big city private utilities. The sudden bevy of power
along the Columbia and the fair rates at which it could be obtained in great
quantity led to an industrial revolution for the region, one that saw it as the
seat of the American aluminum industry (with the Columbia Gorge producing
something like 1/3rd of the nation’s aluminum through to the 1970s) and that
boosted the fate of hundreds of related industries (aerospace and, specifically,
Boeing not least among them). BPA power has enduring influence today, with many
towns on the Gorge (The Dalles, Boardman, Umatilla) disproportionately prominent
on a map of the nation’s data centers. AWS’s us-west-2, for example, is a
beneficiary of Columbia River dams and located near many of them—not just
Bonneville, but the Dalles (1.8 GW), John Day (2.2 GW), McNary (1.1 GW), and
more.

In marketing this power, the BPA faced a challenge: the dams are spread across a
large area, as are the customers. Industrial customers, such as the Alcoa
(Aluminum Company of America) smelter that opened in 1940 at Vancouver,
Washington were opening in rural areas where land was
readily available, and an explicit goal of the Columbia River Project had been
the extension of electricity to farmers and other rural industries. The concept
of long-distance power transmission had been pioneered by an 1889 transmission
line, the nation’s first, between Willamette Falls at Oregon City and downtown
Portland. Beginning in 1938, the BPA was tasked with expanding that concept
across a region that would eventually span eight states.

The Master Grid

BPA’s first administrator, J. D. Ross, presented a plan he called the BPA Master
Grid. This ring-shaped network, made up of 230 kV long-distance transmission
lines, would connect the dams not only to Portland and Seattle but to Pasco,
Yakima, Spokane, Ellensburg, the Willamette Valley through to California, and
the Oregon Coast. By 1945, the Master Grid covered three thousand “Circuit
Miles” of transmission lines. It was the first integrated regional power grid
in the United States, and would come to pioneer the market-based electricity
pricing and distribution, independent system operators (ISOs), and pooling and
wheeling agreements that form the modern US electrical infrastructure. The
entire Western Interconnection, the unified power system that serves the US and
Canada from the Rocky Mountains west, can be said to have crystallized outwards
from the seed of the Bonneville Dam’s switch yard.

Getting there required that the BPA solve formidable technical problems and
develop many new technologies in power distribution. BPA transmission lines
operated at higher voltages than any before them and, in the 1960s, introduced
high voltage DC transmission to the Americas, connecting the Columbia system to
the major demand centers of Southern California at 800 kV DC. BPA was only
slightly behind the TVA on the installation of a remarkable analog computer
called a Network Analyzer, in 1939, which simulated the behavior of the
transmission network like a scale model. The rural nature of the BPA network put
substations in remote areas, where they were minimally staffed, and the long
stretches of high-voltage transmission line meant there was ample potential for
damage by wind, weather, and trees, phenomena that the BPA came to better
understand through research laboratories and experimental field sites.

This is not an article about the history of electrical distribution, or at least
it wasn’t supposed to be, so here we must exercise some discipline and narrow in
on a topic. Telecommunications ought to do.

By 1940, as the Master Grid entered operation, its numerous substations already
caused administrators a headache. Each had a small staff of technicians, but
communicating with them was difficult. Coordinating changes across large areas,
or quickly responding to faults, involved a flurry of telephone and radio calls.
When Portland General Electric built the transmission line from Willamette Falls
to Portland, they encountered the same problem, and by the 1910s had implemented
a very early form of its solution: telemetry and teleoperation. Through a set of
control wires strung along the transmission line, operators in Portland could
see certain measurements from the Oregon City powerhouse and remotely throw
switches to bring turbines on and offline in response to load. As the BPA built
the Master Grid, they invested in the same technology.

Around 1939, the BPA commissioned a study of communications technology that
could be used along the Master Grid. There were three main contenders:
commercial telephone networks (which BPA called “land telephone” to
differentiate it from the other two), “carrier current telephone” technology
that superimposed telephone signals onto the electrical conductors of the
transmission lines themselves, and radiotelephone equipment. A working agreement
was reached with Pacific Telephone & Telegraph, the Bell System company that
would later become US West, to share network information and analyze the cost
tradeoffs between purchasing carrier current and radio equipment and leasing
telephone lines. Ultimately, the diversity of the BPA network required some of
all three.

Each of the BPA’s substations had a building, called the control house, that
contained control and monitoring equipment along with office facilities for the
substation’s operators. A room of each control house was dedicated to carrier
equipment, devices that modulated multiple telephone circuits using frequency
division multiplexing, and to a set of carrier frequencies that could be coupled onto
the transmission lines to be received at the next substation. This equipment is
similar to carrier equipment used in the telephone network, although specialized
to power distribution applications by the choices of carrier frequency. I cannot
say for certain, but it is very likely that BPA purchased their system from
Lenkurt, a San Francisco-based communications equipment manufacturer that
specialized in carrier current systems at the time .

The BPA’s carrier system incorporated selective calling, meaning that users
interacted with telephones that looked and felt much like conventional
telephones, including a dial. An operator at one substation could dial the
number for another and that phone would ring. The main difference from the
telephones we use today is that these carrier current systems were interphones,
more similar to intercoms or party lines than single-user telephone service. If
you picked up a phone on a circuit, you would hear any conversations already
underway. Of course, in industrial control applications, this built-in
conferencing capability was generally considered a feature, and telephone
circuits were assigned to shared use by departments or operating regions.

Radio was installed as well, primarily so that construction and maintenance
crews in the field could get messages back to the administrative offices. Some
substations, in strategic locations for coverage, had a radio site about a half
mile from the substation for isolation from the powerful electromagnetic
interference created by the high-voltage transformers. These radio sites were
wired to remote heads located in the substation control house office, where
substation operators relayed messages between mobile radios in the field and the
carrier current telephone system. Bear in mind that these were still early days
for mobile radios, and the HF units used by the BPA were proudly described as
using only 1.5 cubic feet of space in the trunk of the vehicle, plus the
microphone, speaker, and control head in the cab. Finally, while not the main
purpose, it was already noted in the 1940 Annual Report that the substations
could use the radio stations to substitute for the carrier current system in an
emergency.

Complementing all of the above, the BPA leased telephone lines between major
substations, agency headquarters in Portland, and the switch yard in Vancouver
that was becoming the closest thing to a “main substation” in the network’s
distributed, ring-shaped design.

Immediately after the BPA’s first Annual Report discusses the selection of
communications equipment, it moves on to Protection. Here I must introduce a
topic in electrical engineering that I have only a loose understanding of, even
having spent the last few weeks in part on YouTube engineering tutorials. It’s
important that we get comfortable with the field of “protective relaying”
because, as we will see, it became the most widespread application of private
telecommunications networks after the railroads.

Protective Relaying

In your home, you are protected against certain dangerous scenarios by the
over-current protection device that we Americans call a circuit breaker. The
electromechanical contraptions in your service panel use a combination of
methods to monitor the current that passes through them, and if they detect
excessive current they open the circuit. The electrical transmission system has
similar protections on a larger scale: on the distribution wires strung on poles
outside of your house, for example, there are various fuses and
circuit-breaker-like devices known as reclosers. High-tension transmission lines
, like the 230 kV system built by the BPA, need similar protection for
similar reasons—except that it is much more complex.

Electrical terminology can be complicated on a good day, and this situation is
even more complex because of the historic bifurcation between terms and
practices in building electrical wiring versus electrical distribution (which
are governed, for example, by two separate electrical codes) and the fact that
we are talking about a system that is nearly 100 years old. Relays were a newer
technology in the 1930s, as was large-scale over-current protection, so
transmission engineers viewed circuit breakers as just an application of the
relay and over-current protection on power distribution is still referred to as
“relaying” today. Since the whole broader field of supervising transmission
lines for safety and reliability is called “protection,” relays that open to
protect generators, lines, or loads from dangerous conditions are called
“protective relays.”

Some of the protective relays used in transmission are very much like the
circuit breakers in your home. Directional over-current relays, for example,
monitor the current passing through them in one direction (“towards” the load)
and open if it is excessive. Ground fault relays open when they detect, via
various current transformers, that an excessive amount of power is leaking to
the ground—just like the GFCI outlets or breakers installed in wet areas of
homes.

Some of them, though, are much trickier. The first major problem is
directionality. In your home electrical wiring, there is a clear sense of where
power flows “from” (the service panel) and “to” (an outlet or fixture). Wiring
thus only needs over-current protection in one direction. In a wide-area
transmission network, this isn’t true. The Master Grid was designed to
incorporate a ring for much the same reason that SONET and other communications
technologies favored rings: with a ring topology, you can lose the connection
between two points and still be able to serve all points by sending power the
“other direction.” In general, it is common that electrical transmission lines
can be “fed” from both ends, and have “load” on both ends. This flexibility to
reach the same places by different routes makes the grid more reliable and
responsive to changes. It also makes over-current protection more challenging.

Say that you have a span of transmission line, and that somewhere along it a
tree falls and pushes one conductor against another. You now have a
short-circuit fault at 230 kV (or more in later lines), a dramatic and
dangerous condition. You also have thousands, if not hundreds of thousands, of
customers that are depending on the power provided by that line. Current
transformers can measure the enormous fault current, and indeed it will be
detected at many points along the line. But what do you do?

Ideally, protective relays should open on both sides of the fault, and as close
to the fault as possible. This cuts power to the dangerous situation while
minimizing the number of customers who experience an outage. It’s also difficult
to achieve in practice: you cannot simply open a protective relay on
over-current, or every relay on the line will open at the same time. Instead,
analog circuits were used to measure the impedance to the fault as a proxy for
its distance. This way protective relays could be carefully tuned to open only
when a fault was near them.

Now, consider that a transmission line may be “tapped” and connected to load
centers or generation at multiple points along its length. There may also be
multiple parallel routes that current can take, with varying capacities. Both of
these situations mean that it is often necessary to measure the current (to
detect faults) at locations remote from the actual protective relays, which are
large devices that needed to be located at substations. Further, the
complications of parallel routes and possible ground faults on long lines
required the use of a “differential protective relay” or “balanced current
relay” that took a much higher level approach to the problem. In a differential
system, you measure the current at every connection point to a given protection
zone and sum them. The sum should be zero: the same amount of current goes into
the line as comes out. If it’s not, something has gone wrong somewhere, likely
current that is escaping to ground or traveling on a parallel route not
engineered for such abuse. But the points where you measure current may be
many miles apart, and you still need to make real-time comparisons between them.

In 1940, the BPA was already planning the installation of “pilot relaying” over
their carrier current telephone system. In an engineering context, a “pilot” is
usually something small that controls something big. A pilot operated relief
valve (PORV), for example, is an arrangement where dangerous pressure levels (of
a liquid or gas) cause a small pilot valve to open which then triggers a
pressure differential in a much bigger valve that causes it to open. There is a
similar idea in protective relaying: a pilot-operated relay is a relay that
disconnects a very big wire under the control of a smaller wire carrying a pilot
signal. The simplest scheme works like this: a device, like a current
transformer, monitors a safety parameter and produces a tone whenever it is
acceptable. Elsewhere, a protective relay monitors that tone. If the tone ever
goes away, the relay opens. The tone might go away because the pilot device
detected an unsafe condition, but it might also go away because the line
carrying the pilot signal was damaged, making it a fail-safe design. This is
good for safety, but bad for reliability, and requires that the communications
infrastructure used for protective relaying be very reliable.

Unfortunately, it was not: the carrier current systems installed by BPA through
the 1940s were typical of the technology used in the industry at the time, but
it was ill-equipped for the scale of the Master Grid. In part to alleviate
concern of federal competition wiping out private utilities, and to improve
general efficiency, the BPA formed the Northwest Power Pool in 1941. Initially
made of about a dozen electrical utilities in the Pacific Northwest, the Power
Pool formalized a set of arrangements by which utilities would buy and sell
power among themselves, carried over the BPA’s transmission network for a small
“wheeling” fee. The Northwestern Power Pool would eventually become the Western
Power Pool and a template for much of the nation’s electrical industry. It
significantly increased reliability and efficiency in the region by allowing
utilities to sell their overproduction to utilities with high demand, and vice
versa. It also brought the carrier communications system to its knees: a
practical requirement of the power pool arrangement with wheeling over the BPA’s
transmission lines was that those transmission lines had to carry protective
relaying pilot signals for all of the utilities involved.

A severe fault in a utility taking power off of a BPA line, for example, might
require opening protective relays at a power plant operated by a different
utility somewhere else on that line. New techniques for communications-aided
protective relaying were under development, things like “permissive
underreaching transfer trip” and “permissive overreaching transfer trip” that
are difficult to explain briefly. These required that protective equipment at
each substation have information about the state of protective equipment at all
of the other substations, in order to make decisions that are not just based on
local conditions but are globally optimal for the health of the whole line.

For example, avoiding a dangerous “islanding” condition on a transmission line
might require opening relays at three or more locations along the line, but
opening any relays beyond those required would simply cause unnecessary outages.
Further, reliability is key and some types of faults on high-voltage lines are
self-clearing (this is sort of a euphemism for the fact that a tree branch
bridging sufficiently high-tension conductors will often be knocked off of them,
if not vaporized entirely, by the resulting arc). Some protective relays are
“reclosing” (and are often referred to in brief as “reclosers”), meaning that
they will automatically reset (close) after a brief wait period. Some of the
time, the fault will be gone and service is restored. Reclosing is potentially
dangerous, though, and especially in transmission networks reclosing is only
desirable in certain circumstances. Further pilot signals can be used to enable
and disable reclosers based on the nature of the fault or the other locations at
which it was detected, so that for example a fault that has taken a power plant
offline does not lead to a recloser elsewhere “flapping” and stressing the
remaining production capacity.

By the end of the 1940s, the BPA’s carrier telephone system was overstressed to
the point of failure. Power Pool utilities had connected their own carrier
equipment, butting frequency bands so closely against each other that they began
to interfere and degrade the quality of connections that could already be
difficult to make out over hundreds of miles of high voltage infrastructure.
The fact that a fault on a transmission line would generally prevent carrier
current communications over that line working was a feature for simple fail-safe
pilot relaying systems, but as protective relaying technology advanced it became
the source of cascading failures. For example, by the early 1950s the BPA had
found that lightning strikes on major transmission lines would cause enough
interference to the carrier current system that protective relays all along the
line would lose their pilot signals, open as fail-safe, and escalate what should
have been a localized problem into a systemic one. Besides, many sections of the
network had by that time become so congested by various carrier current circuits
that there was simply no room in the spectrum for more—and so no capability to
install protective equipment for new service lines.

Microwave

Meanwhile, the Second World War had had a profound impact in two ways: first,
wartime demand for weapons, aircraft, and aluminum had driven Pacific Northwest
industry to new heights. In 1949, power consumption in the Pacific Northwest had
more than tripled, and population increased by 45%, compared to 1939. The Corps
of Engineers built more dams, so the BPA’s network carried more power.
Engineers at the Administration’s laboratory
developed the techniques to operate transmission lines at record-setting
voltages, 300 kV and beyond—making protection systems all the more critical.
Second, wartime radar research had produced technological byproducts including
high-bandwidth microwave transmitters and receivers.

So, the electrical industry adopted microwave communications technology
alongside the telephone industry, and for much the same reasons. The high
bandwidth of microwave links allowed for multiplexing huge numbers of channels,
and the lack of wireline infrastructure (especially shared with the actual
transmission lines) promised increased reliability. In my previous article on
passive repeaters,
I noted that they were especially popular with electrical utilities. Now, we
learn why: utilities throughout the country built microwave communication
systems that carried a fraction of the traffic of the Bell System, but often
carried it to more remote locations and with higher reliability requirements.

The BPA’s situation was different from that of more traditional utilities. Most
private electrical utilities had started in a city and grown outwards, with a
denser service network and fewer long-distance lines. They had mostly built
private networks for communications, stringing their own open-wire telephone
lines between stations. The BPA, with its far-flung network and huge distances,
couldn’t afford that kind of investment in stringing wires. In some ways, this
proved an advantage: they could start from a clean slate. This network would be
architected from the beginning for efficiency and performance, rather than to
accommodate existing infrastructure.

While the BPA had initially built substations for a larger staff, the control
technology was rapidly evolving and some of the more intensive activity BPA had
expected at substations proved unnecessary . Despite the generously sized
control houses, by 1950 most substations had only a single operator on staff,
who would often be “out in the field” tending to the transmission lines. This
created a problem if some sort of sudden problem required reconfiguring the
network to restore service—a system operator might be left ringing a substation
phone with no one there to answer.

That year, three substations had been equipped with “supervisory control”
technology. This new system combined telemetering and teleoperation, so that a
system operator in Portland could monitor voltage and current measurements at
the substation and remotely operate the switchgear. The benefits of supervisory
control were obvious, but the limitations of the carrier telephone system meant
that those three substations were as far as the system could reach. Based on its
promising experience with supervisory control of those three stations, and the
clear need to continue expanding an already-stressed communications system, the
BPA in 1949 committed to the construction of a completely new, completely modern
control system for the Northwest Power Pool.

The BPA’s substation in Vancouver, already one of the largest, had a combination
of ample space and proximity to Portland that made it a convenient location for
support facilities. Construction yards, maintenance shops, and research
laboratories had all been added onto the facility. The 1949 project launched
with a symbolic gesture: the site was renamed, from simply the North Vancouver
Substation to the J. D. Ross Complex in honor of the BPA’s first administrator.
A new building at the Ross Complex, the Control Center, became the nerve center
of the system and the Rome to which all microwave routes led.

Keeping with our communications theme, one of the main features of what was then
called the Ross Control Center was a “three position turret” (yes, a turret!) by which operators could call any line on
the microwave, carrier current, or leased line telephone networks. The plan was
to obsolete the turret, though. In 1950, the BPA awarded a half-million-dollar
contract to the Philco corporation (originally Philadelphia Battery and later
part of Ford, then GTE, then Philips, amusingly providing another expansion of
the name) for its new microwave network. Philco had done extensive military work
on microwave radar during the war, and was at the time one of the leaders in
microwave technology. Philco’s expertise would be needed, because the microwave
network ordered by the BPA would be the largest electrical utility communications
network in the world. While more difficult to conclusively state, I think it is
likely that it was either the second largest microwave network of any kind after
AT&T’s, or the third largest after those of AT&T and the Santa Fe Railroad
(both of which were also Philco customers).

At this point, the BPA’s transmission network had extended to the Hungry Horse
Dam in northwestern Montana, adding customers along the way. There were some
14,000 circuit miles of transmission lines and 400 substations in the system,
and Philco’s contract specified that they would build out the initial operating
network in just 360 days. Work got underway: BPA signed the contract in February
of 1950, in September testing and demonstrations were conducted, and in October
the BPA officially activated the first leg: a 200 mile route from the Ross
Complex to Snohomish, Washington.

Snohomish

This first route, built at a cost just under a million dollars, used repeaters
at Mt. Rainier, Chehalis, Olympia, Squak Mountain. The longest single jump was
Olympia to Squak Mountain, about 55 miles, an unusually long distance for
microwave facilitated by Squak Mountain’s prominence and a 150′ tower at
Olympia. With multiplexing equipment, this route carried 23 channels from the
control center to the Puget Sound area.

This first microwave link was quickly put to work for one of the most
interesting new applications of utility telecommunications: fault locating.
When a fault occurred on a long transmission line, the BPA’s first step was to
search the whole line for the problem. Many lines were in difficult terrain, so
a helicopter or airplane was used to speed up the process. The faults were
sometimes minor and not easy to see from the air (say, a broken insulator), so
the survey aircraft would take photos for processing and analysis on the ground.
This process was expensive and, moreover, it was time consuming. BPA engineers
realized that sudden open circuits or shorts in transmission lines created
electrical signals that propagated back through the line and could be observed
on test equipment—so you could presumably locate a fault by calculating its time
of flight to the substations at each end. The problem was obtaining a
measurement of when the fault signal arrived at two different locations, in
precise synchronization.

Requiring high speed and, more importantly, consistent latency, this was exactly
the kind of problem that microwave lines were well suited for. ITT designed the system to BPA
specifications, including devices that detected fault waves and reported them
over a microwave channel, and a machine that compared the timing of the received
reports and calculated a likely fault position (in miles) relative to each
substation. FTL seems to have estimated that the system was accurate to 600′,
BPA to 1,000′.

The Ross-Snohomish route carried other important traffic as well: as part of its
inaugural celebration, Washington State Representative Henry M. Jackson used the
new internal telephone at Snohomish to call Ross over the microwave link,
congratulating BPA’s administrator and chief engineer on the accomplishment.
Although I am unclear on the exact criteria being used, newspaper reports
consistently identify the link as the “first of its kind in the world” .

1950 was still early for microwave technology; AT&T’s first commercial microwave
link had only gone into service in 1948, and that was experimental. The
transcontinental telephone “skyway” wouldn’t be completed until a year later.
As a result, microwave technology was unfamiliar to the public, and the
appearance of parabolic antennas on BPA facilities—and at repeater stations on
mountaintops and out in the woods—was conspicuous. One reporter called them the
BPA’s flying saucers, another explained the repeaters in terms of “pitcher” and
“catcher.” Every paper ran photos.

Over the next two years, Philco completed a second microwave route
up the Columbia Gorge connecting each of the dams through to Spokane, and a
third that linked Beverly, on the route to Spokane, to Snohomish—forming a ring
like the original Master Grid that provided redundancy and direct protection
channels for transmission lines on that route. The 1952 microwave network
included fourteen primary terminals and 21 repeaters; it connected the dispatch
telephone system at Ross with dams and substations along the microwave routes
as well as seven mountaintop HF stations to reach field crews.

As was typical at the time, the microwave equipment at each repeater and
terminal ran directly from battery power. The batteries were charged (normally
floated) from two different power supplies, one from the utility and the other
from an on-site propane generator with a two week fuel supply. BPA initially
used prefabricated aluminum shelters for the equipment at repeaters, although
many were originally built or later rebuilt as cinderblock. This was, in part,
due to the weather: mountaintop repeater stations in Washington coped with
severe winters, and BPA went through several rounds of modifications to their
building and tower designs. Towers were reinforced against ice accumulation,
and repeater stations in particularly snow-prone parts of the Gorge and the
Snoqualmie Pass were made two story. These buildings had a “balcony” entrance
on the second floor with a ladder to reach it, allowing access even when the
first floor was completely buried in snow. Towers were rated for 100 MPH winds,
and some for thousands of pounds of ice. BPA designed ice shields for the
antennas, and a heated cover to keep ice from covering the reflector surface.

BPA also took advantage of passive repeaters to relocate microwave sites to more
accessible locations. At Rockdale, on the edge of the Cascade Mountains, a
repeater was installed just next to the highway. Its antennas aimed more upwards
than sideways, at reflectors at the top of the mountain ridge. Microflect
passive repeaters were manufactured in Oregon, and the BPA was one of
Microflect’s first large customers, contributing design changes for mountainous
service.

By 1955, the BPA microwave network had reached Hungry Horse Dam in Montana and
connected all of the major substations of the system. When a decision was made,
in 1955, to relocate the power dispatch office from the Ross Complex to the
new Portland headquarters, the capacity and expandability of the microwave
system made the process much easier. The BPA’s new HQ building looked more like
a telephone exchange than a federal building: one of its most prominent features
was a rooftop microwave tower. The 1957 annual report inventoried 61 microwave
radio sites covering 1,300 miles of route, by then using a mix of Philco,
ITT, and Motorola equipment.

BPA’s network had, by this time, achieved many feats of rural service. One of
the most impressive was service to the southern Oregon Coast: this area was very
remote and faced terrible weather throughout the winter. BPA’s 115 kV South
Coast line was the only electrical service into the region, and it was regularly
disabled by ice storms and flooding. Because of the area’s mountainous terrain,
line crews working in the area were only infrequently able to reach a substation
near Eugene on their mobile radios, and that was their only way of talking to
dispatchers to coordinate repairs. In an effort to improve service reliability,
the South Coast became the pilot for a new model of field communications.
Relatively closed spaced microwave repeaters, each with a VHF radio, would
bridge radio channels onto the microwave telephone system. To stand up to the
Oregon Coast, each of these stations used an aluminum enclosure with heating,
fire suppression, and a generator. Some of the enclosures were cabled to the
ground, to better hold them down against the wind.

During the 1960s, the value of the microwave system had been proven but it was
once again facing the limits of its capacity. Microwave technology had improved
tremendously in the post-war decade and BPA’s 23 and 24-channel multiplexers
were obsolete. A $1.6 million contract was let to Lenkurt to upgrade much of the
microwave network to the modern Lenkurt 76C microwave radio and 46A or 34A
multiplexers, capable of up to 600 channels at around 8 GHz (the previous
system varied from site to site but operated at around 2 GHz).

This was equipment designed and built under GTE ownership, and was also typical
of the long-distance microwave links in the GTE telephone network. As part of
the project, Lenkurt also installed VHF radio relays throughout the system. At
some sites, Lenkurt installed dual-polarized antennas to allow simultaneous
operation of the old and new multiplex systems and, later, increased capacity.
Further contracts expanded the microwave network to Bellingham, Washington and
to Corps of Engineers projects on the Snake River. In 1966, BPA dispatchers in
Portland could monitor production at 21 dams, receive alarms from 250
substations, and completely remote control fifteen of the network’s key
switchyards.

When the BPA built the Pacific Intertie, a combination of two 500 kv AC circuits
and one 800 kV DC circuit stretching 900 miles from the Columbia River to near
Los Angeles, it was the largest transmission line project in US history.
Under construction from 1965 to 1970, the line’s standard bearer came in
microwave form. Collins Radio built microwave routes parallel to the Intertie
transmission lines, a $2 million project with 22 new radio stations on the
600-channel Lenkurt system. Most of the work was finished by 1967, a
prerequisite for some construction the transmission line itself, since the
microwave channels were used for testing and commissioning.

The Computer Age

Microwave was not the only arena in which the mid-century had brought new
technology. The BPA was not new to computers; various forms of electromechanical
computation had been part of their engineering works since the 1930s. By the
1960s, though, projects like SAGE (a military air defense system) and SABRE (a
commercial airline reservation system) demonstrated the potential of combining
computers with telecommunications for real-time control. The BPA had a
telecommunications network, and it had a real-time control system… and they
decided to add a computer.

In 1966, the BPA announced that its control center would once again move, from
the Portland headquarters building back to the Ross Complex, where a new
building would be designed from the ground up for centralized, computerized
control of the power system. Named the Dittmer Control Center after a previous
BPA power manager, the low-slung building had a prominent concrete microwave
tower and was partially sunk below ground level for hardening against attack (it
was, after all, the Cold War).

Much of the Dittmer center’s lower-level floorspace was devoted to equipment
rooms, which would soon be the home of the computer system that BPA contracted
to Rockwell. Among other equipment, Rockwell installed a PDP-10 computer that
received, analyzed, and logged telemetering data from throughout the system for
display to operators. From its commissioning in the early 1970s, BPA continued
to enhance the computer center into an integrated power dispatching system that
supported operators in monitoring the network, predicting future demand,
switching transmission lines, and ordering changes in production at power plants
throughout the Pacific Northwest.

The ultimate manifestation of the PDP-10’s software was called RODS, the
Real-Time Operations, Dispatch, and Scheduling System. RODS was one of the first
systems of its kind, initially contracted to Rockwell in part due to their
experience with control computers for the Apollo program. Features of RODS
included a time-synchronized data acquisition system to support differential
current monitoring (ensuring that the computer compared current measurements
taken at precisely the same time), which used an atomic time standard at the
Dittmer Control Center to distribute high-precision timecode through the
microwave network. As RODS matured, it established the 15-minute scheduling loop
used by dispatchers to configure power plants and transmission lines for a
constantly changing electrical load. DEC themselves, in an internal sales
meeting whose minutes fortunately made it into the historic record, noted the
Dittmer PDP-10 as a critical early sale in their efforts to break into the
utility industry.

Despite the technical firsts of the Dittmer Control Center and RODS, this
chapter of BPA history is best known for its incidental brush with the Pacific
Northwest’s most famous chapter of computer history: as temporary employees of
TRW, the aerospace contractor brought on for RODS software development, Bill
Gates and Paul Allen both spent time at Dittmer. They were still in high school,
it would be years before they moved to Albuquerque to found Microsoft.

Many parts of the BPA’s microwave network are still in use, although improving
radio technology and the adoption of fiber optics (including fiber embedded into
the neutral conductors of transmission lines) have allowed for elimination of
some repeaters. As microwave technology continues to fall obsolete (in
comparison to fiber, commercial terrestrial radio networks, and satellite),
many of the remaining sites are likely to be demolished. Some of them—sites like
Chehalis, Squak Mountain, and Rainier—have been in service for 76 years.

The BPA microwave network is not unusual. It was the first of its type, but the
transmission and power marketing concepts pioneered by the BPA are now used
nationwide. Wherever power goes, protective relaying follows, and the
telecommunications networks that shadow the electrical grid from coast to coast.
Few enterprises outside of the communications industry itself have ever operated
communications networks on the scale of electrical utilities. They find
themselves in the company of railroads and oil pipelines, ventures that must
span deserts, climb mountains, and cross rivers.

Unlike many of those operations, though, the BPA is a federal agency, subject
to the National Environmental Policy Act and National Historic Preservation Act.
BPA’s extensive Section 106 NRHP compliance program has produced extensive
historic documentation of its transmission lines, communications infrastructure,
and research facilities. While sometimes onerous, these federal policies have
created the best-documented historic electrical utility communications system
in the nation.

An inventory of historic microwave stations still under
BPA ownership turned up 28 in Washington, 22 in Oregon, one in Idaho, and two in
Montana, and many are eligible for nomination to the Historic Register. From an
aluminum shed at the Ross Complex to a squat concrete building and utility pole
at Mary’s Peak, they are monuments to American history—a singular, almost
megalomaniacal vision of the Columbia River tamed; the rise of Pacific Northwest
industry under wartime demands; a technical approach to environmental
preservation and economic equality. Infrastructure for the public benefit: a
great American achievement. We might, one day, find the will to do it again.