Telluride Power Co.
Pioneering ac in the Rocky Mountains
High in the grandeur of the mighty Colorado Rocky Mountains, a power company was born that undertook a variety of trailblazing efforts that would significantly benefit the power industry for years to come.
Perhaps in no section of America has the drama of electrical development been more vividly portrayed than in the majestic Rocky Mountains of Colorado’s Western Slope. Here, atop the spine of a mountain range so high one draws deep breaths after taking 100 steps, some bold and committed men set about doing the impossible. Their efforts would ultimately pave the way for the evolution of electric generation and transmission nationwide.
The San Juan Mountains of southwestern Colorado became the setting for one of the more significant and exciting chapters in the history of the Old West. These mountains are uniquely enriched with ore deposits, but the ruggedness of the area has always impeded exploration and production. Nearly a quarter of all the 14,000-ft (4,267-m) peaks in North America are located in the San Juan Mountains. As one would imagine, nature unleashes its fury in the form of heavy snows, avalanches, winds, ice, and lightning. This pristine wilderness was described by Hubert H. Bancroft in 1890 as “the wildest and most inaccessible region in Colorado, if not in North America,” a region of “unparalleled ruggedness and sublimity more awful than beautiful.” The description holds true today (see Figure 1).
The gem of the mountains is the Telluride area, a breathtaking visit for people today. Telluride was originally named Columbia, but due to confusion with Columbia, California, the name was changed by the postal department in 1887. The name Telluride is taken from an ore (a combination of the element tellurium with high gold content and some silver).
The mining of precious metals began in the Telluride area in the 1870s. As it did in other areas of the west, the mining boom brought railroads, stagecoaches, freight wagons, and adventurers seeking to make a fortune. The construction of narrow-gauge railroads and toll roads in this area by Otto Mears and the Rio Grande Southern Railroad was nothing short of spectacular.
In the late 1890s, while the so-called “battle of the currents” between the proponents of direct current (dc) power and those favoring alternating current (ac) power was in progress, George Westinghouse was presented an opportunity to deploy his ac system over 1,000 mi (1,609 km) away in this historic area of southwestern Colorado. Several significant electrical engineers would be involved with the Telluride system, including Nikola Tesla, V.G. Converse; and the following three men who served as American Institute of Electrical Engineers (AIEE) president in the years shown: Lewis B. Stillwell (1909–1910), Charles F. Scott (1902–1903), and Ralph D. Mershon (1912–1913).
This article focuses on the beginning of the Telluride Power Company and the challenges it faced, including the historic Ames hydroelectric plant and its first line to the Gold King Mine. Of particular interest are the pioneering real-time experiments evaluating the performance of ac lines at various high voltages. The initial expansion of the power system, including the challenge of constructing and maintaining power lines over mountains as high as 13,000 ft (3,962 m), will be discussed as well. The aim is to provide a good understanding of the significant contributions made to the power industry by the Telluride Power Company.
In 2003, accompanied by my wife Kathi, I had the opportunity to explore some origins of the Telluride Power Company, which included a hike along the route of the original power line from the Ames power plant to the Gold King Mine. This exploration significantly heightened my admiration for how these pioneers addressed the challenges of constructing and maintaining a power system in this environment.
The complete story of this entrepreneurial company (and its ultimate contributions to the industry) is beyond the scope of this article. I hope to follow up with a sequel, so a complete documentation of these contributions can be realized.
Here, then, is the story of the beginning of the Telluride Power Company.
L.L. Nunn and the Beginning
Once known as a prime area for gold and silver mining, Telluride had fallen on hard times, a result of significant increases in energy costs. The mines used heavy excavating machinery that consumed enormous amounts of power, exhausting the majority of the area’s fuel source, timber. Gold remained in the hills, but mining costs escalated to the point that mining was no longer profitable.
The consequence of this predicament was that if mining continued to decline, the town of Telluride would disappear. This fact was well understood by Lucien L. Nunn, an Ohio native who owned the local San Miguel County Bank. A man barely 5 ft (1.52 m) tall, Nunn was a dynamo of energy, not reluctant to take risks in entrepreneurial endeavors (see Figure 2).
In 1889, three outlaws came to town and robbed the San Miguel County Bank of US$20,000. Upon their escape, a posse was formed, which included Nunn, an accomplished horseman. As the chase ensued, Nunn rode ahead of the posse and caught up with the robbers, who promptly disarmed him, took his horse, and sent him back toward town. It was later determined that the leader of outlaws was, in fact, the notorious Butch Cassidy.
Nunn’s responsibilities included financing and managing several mines, one of which was the Gold King Mine (see Figures 3 and 4). The Gold King Mine, needing low-cost fuel (as was typical in the region), was located only 3 mi (4.83 km) from the confluence of two mountain streams that formed the South Fork of the San Miguel River. Nunn had been following the growth of electricity closely, especially the “battle of currents” in the east. He concluded that this location had adequate flow to power a small hydroelectric facility.
Nunn, having a vested interest in the Gold King Mine, hired his brother Paul (a fledging electrical engineer) to design a power plant and line to the mine. The Nunns pondered dc, but they had a better feeling about ac and took a chance that Westinghouse’s ac system was the answer. L.L. Nunn went before the Westinghouse board in Pittsburgh, Pennsylvania, personally, to request the necessary equipment to construct an ac power plant and transmission line. At that time, it was a risky venture, with no track record from which to judge.
Nunn made Westinghouse a bold proposal: US$50,000 in gold for US$50,000 worth of his time and experience to build an ac generator and a 100-hp motor to run the mine machinery. George Westinghouse viewed the proposal optimistically, understanding that success of the project could serve as positive proof of the superiority of his ac system. Westinghouse reasoned that if an ac system could send power over a remote section of the mighty Rocky Mountains, it could work anywhere. The project was a go, with Westinghouse providing the equipment and engineering assistance (see “L.L. Nunn”).
Ames Power Station and the Gold King Mine
The name Ames came from a small settlement that existed at the confluence of the Howard Fork and Lake Fork streams, which in turn formed the San Miguel River. The plant consisted of a wooden shack located 2,000 ft (610 m) below the Gold King Mine, which was at an elevation of 12,000 ft (3,658 m) (see Figure 5). A continuous supply of water was provided by the waters of the Howard and Lake Fork streams and a system of natural reservoirs above the plant. The water was transported to the plant with a head of 320 ft (97.5 m) through a 2-ft (0.61-m) diameter steel pipe, to a 6-ft (1.83-m) Pelton water wheel.
In the summer of 1890, Westinghouse sent two identical 100-hp, 3,000-V, single-phase 133-Hz ac generators (accompanied by additional materials) to Nunn at Telluride (see Figures 6 and 7). The system was designed with one unit utilized as the generator at Ames and the other as a motor at the Gold King Mine (see Figure 8). The generator at the Ames plant was separately excited, while the motor at the Gold King Mine was self-exciting (see Figure 9).
The rudimentary switchboard was made with shellacked pine wood, upon which the crude measuring instruments and disconnects were mounted. The voltmeters and ammeters were of both solenoid and gravity-balance type, mounted in black walnut wooden boxes with glass covers.
The line to the Gold King Mine was approximately 3-mi (4.83-km) long and was constructed using poles approximately 30-ft (9.1-m) long with Western Union telegraph-style crossarms, wood pins, and glass insulators. Two no. 3 bare-copper wires were installed over the entire line. The cost of the conductors was about US$700, about 1–2% of the cost of the larger copper conductors that would have been necessary if a dc system had been selected.
The main motor at the Gold King Mine was brought to synchronous speed by a single-phase induction motor, which received full line voltage. Synchronizing lamps were utilized to assist with synchronization. Circuits were closed with blade-type switches and opened with arc-light plugs. Operating the plant was a hazardous endeavor, and it was a rule that operators always keep one hand in their pocket when using the other (see Figure 10).
Nunn hired students from Cornell University to help construct and operate the Ames power plant, along with the line to the Gold King Mine. On 19 June 1891, water from the San Miguel River was unleashed onto the 6-ft (1.83-m) Pelton water wheel. The wheel was attached by belt to the Westinghouse generator, whose armature began to rotate as the water wheel turned. The ac produced by the rotating armature was transmitted 3 mi (4.83 km) to successfully operate the 40-stamp ore crushing mill at the Gold King Mine. This was arguably the first use of ac for industrial use in the United States.
The plant ran continuously for 30 days without any problems. It became an entertaining event for the local citizens to go out to the Ames plant and observe it in operation. A common question asked by spectators was “How long does the electricity take to get to the Gold King Mine?” If fortunate with their timing, spectators could observe some of the 6–8-ft (1.83-m to 2.44-m) vicious arcs drawn when the circuit was opened.
Another serious challenge for these early pioneers was the lightning activity that frequently occurred at this altitude, causing damage to the equipment. It was not uncommon for workers to spend painstaking hours replacing generator or motor coils damaged by lightning surges. Fortunately, the design of the generator and motor was such that the armature windings were segmented into removable coils that could be replaced individually when damaged. During summer months, it was standard operating procedure upon the approach of a thunderstorm to lay out, ready for instant use, an extra armature coil, together with all the tools for immediate replacement.
One of the first lightning-protection measures involved raising the generator and motor and placing insulated platforms made of 4-in2 (10.2-cm2) oak boiled in paraffin for added insulation underneath them. In addition, a variety of trial-and-error lightning arrester designs (mostly utilizing choke coils) were experimented with (see Figure 11). Alexander J. Wurts of the Westinghouse Electric Company ultimately came up with a nonarcing metal arrester design that, for the most part, protected the equipment until more effective arresters were developed.
A problem that developed in the infancy of hydroelectric power generation was the lack of a reliable governor that was sensitive and responsive to insure a constant speed. At the Ames plant and other very early plants, the “one-man automatic regulator method” had to be used. This method required the operator to sit with his hand on the lever of the deflecting nozzle and his eye continually observing the voltmeter or tachometer. He would make adjustments as necessary to maintain the proper rotation and frequency. This method was soon replaced with an automated version developed by the Westinghouse Company.
High-Voltage Experiments at Telluride
In 1895, L.L. Nunn (now general manager of the Telluride Power Company) recognized the need for more research and development regarding longer-distance power transmission. Nunn knew that, in many cases, the source of hydroelectric power would be located much farther from where the power was needed than in the case of the Ames plant. This would obviously require higher voltage levels than had been experienced to date. To that end, he made arrangements with the Westinghouse Electric Company to host a joint research project using his system at Telluride.
The general plan was to utilize the power source of the Ames plant and line to the Gold King Mine for various experiments at high voltages. It was determined that the research project should focus on line losses, voltage drop, corona discharge, and general insulator performance. As a secondary objective, the performance of various styles of lightning arresters would take place as opportunities presented themselves. The project would be directed by noted engineers V.G. Converse, Ralph D. Mershon, and Charles F. Scott.
The line consisted of 62 poles, with each pole having three crossarms supporting three single-phase circuits, with equal spacing between conductors on all three crossarms. The distance between conductors varied during testing but was always be the same for all three circuits. Three different pin-type insulators were utilized for comparison during testing. The glass Pomona insulator was supplied by the Westinghouse Electric Company, so named for its prior use on the historic 1892 10,000-V transmission line from the Pomona hydroelectric plant to San Bernardino, California. Another smaller glass insulator was furnished by the Locke Insulator Company of Victor, New York, a pioneer in high-voltage insulator design and manufacturing. The General Electric Company supplied the only porcelain insulator used, a dry-process, white-colored unit used on several early lines.
Each crossarm supported two of the same pin-type insulators, used to name the circuits: the General Electric circuit, Locke circuit, and Pomona circuit (see Figures 12–14). The Pomona insulator shown in Figure 13 is quite rare and highly sought after by insulator collectors, bringing upwards of US$10,000 when available for sale. In the 1960s, an employee of the Hemingray Glass Company in Muncie, Indiana, who was an insulator collector did some digging at the factory dump. On one dig, he found a cache of unusual insulators, including the one shown in Figure 14. The embossing on the front of the skirt reads: “WESTINGHOUSE ELECTRIC & M’F’G CO./ PITTSBURGH, PA” and on the rear: “TELLURIDE TYPE C.SB.” It would seem that this insulator was made for some test or application for the Telluride Power Company that never occurred. It is the only one that has been found to date.
Initially, all three circuits had no. 8 Birmingham wire gauge (B.W.G.) galvanized iron wire installed. During the test period, the General Electric circuit was reconductored with no. 6 Brown & Sharpe (B&S) copper wire. This arrangement allowed the test circuits to be energized at different voltage levels for different periods of time and weather conditions. The visual observance of insulator performance and corona discharge at night was part of the testing procedure.
Transformers were the key element of the experiment, as the ability to create different voltage levels was of paramount importance. The transformer arrangement consisted of two main transformers: one for raising generator voltage and the other for reducing voltage for the motor (see Figure 15). The high and low voltage windings were divided into individual coils that, by changing connections, allowed both the high and low voltages to be adjusted. This allowed the range of voltages for testing to be between 3,000 V and 60,000 V.
A variety of wattmeters, ammeters, voltmeters, and instrument transformers were utilized to measure the watt loss of the lines (see Figure 16). Various schemes and connections were tried in an effort to find the most accurate method. The majority of testing was conducted on the low-tension side of the main transformers, with the lines open ended at the Gold King Mine. Compensations were made for various transformer losses when necessary so they wouldn’t be included in the line-loss measurements. The line losses obtained were a combination of those occurring between the conductors, leakage from the insulators, and resistance of the conductors.
Conducting the Tests
The first testing was done without any attempt at measurement, since the participants were unsure what would happen to the line and equipment at these higher voltages. After the initial excitement and uncertainty, the remainder of the testing was conducted in a more planned and structured manner. The line would be energized for different periods of time at different voltages, from 3,000 V to 60,000 V. The spacing between conductors was also changed for certain tests. Various measurements and observances of the insulators would be made at each test voltage. Notations regarding weather conditions were also made and correlated with the measurements.
Near the conclusion of testing, the participants decided to stage one grand final test by taking the voltage level up to 133,000 V. To set the test up, they removed a span of conductor from the Pomona and General Electric circuits, leaving a short line of 500 ft (152 m) from the power house to the end of the line. The voltage was run up to 110,000 V, held for a short period, and then increased to 133,000 V. The voltage was held for several minutes until the current jumped from the terminals of the transformers to the iron case, shutting down the plant. Apparently, it was quite a show, providing some anxious moments for the awestruck participants.
One of the test objectives was to compare and determine losses between differently spaced conductors. Numerous tests were conducted with the following horizontal conductor spacing: 15 in, (38.1 cm), 22 in (55.9 cm), 35 in (88.9 cm), and 52 in (132.1 cm). The test results were graphed with curves (see Figure 17). As the graph indicates, engineers confirmed that line losses decreased when the distance between conductors was increased. Another focal point of the watts-loss tests was to determine the influence of varying weather conditions on line loss. A series of weather recordings were made at the Ames plant and Gold King Mine of the following elements, each day over a 33-day period: barometric pressure, temperature, humidity, wind direction, and wind velocity. It was concluded that line losses between conductors are not affected by weather conditions, with the exception of precipitation, which did increase line losses.
Insulators were observed during the day and night at various voltages. Corona discharges occurring as voltages increased were observed and noted. Mershon concluded that there was no advantage to porcelain over glass, unless it was a slight increase in mechanical strength. He summarized that glass insulators were cheaper, lighter, more easily tested and less likely to be shot at than porcelain. His theory on gunshot vandalism was that the white porcelain provided a more tempting target than the green glass. Different lightning arresters and choke coils at line terminals were also the subject of experimentation.
Up to that point, almost all theories of transmission line operation had been predicated upon studies with minimum testing conducted in laboratories. Based on these new tests, Mershon concluded that 40,000 V was a perfectly conservative operating voltage to be utilized on properly designed lines in the future. This clearly led to elevation of transmission voltages, as the Telluride Power Company would later construct a line in Utah operated at—you guessed it—40,000 V.
The success of the initial installation at the Ames plant led to expansion of the system to other fuel-depressed mines in the Telluride area. The Telluride Power Company was officially established around 1895, with L.L. Nunn as general manager and his brother Paul N. Nunn as chief engineer. Westinghouse had gone on to develop the Tesla system, which vastly improved the efficiency of electric power for mining with a three-phase system of generators, transformers, and motors.
In 1896, Nunn had the Ames plant completely rebuilt with a new three-phase system supplied by a pair of two-phase generators directly connected to the Pelton-style water wheels, which were supplied by an increased flow of water from a newly designed storage dam and penstock system. Twelve 100-kW generator step-up transformers were connected to convert the generated two-phase power to three-phase power, elevating voltage to 10,000 V for transmission to various mines.
With a transmission voltage of 10,000 V, the Telluride Power Company now had the potential to serve mines upwards of 20 mi (32.2 km) from Ames. A majority of these mines were located to the northeast of Telluride, in the high mountain areas. This formidable obstacle did not stop these pioneers as they proceeded to extend lines to several mines, including the famous Camp Bird Mine.
Extending the system to mines in this area meant the lines would have to traverse mountains at elevations up to 13,000 ft (3,962 m), where severe weather (including snowstorms, avalanches, winds and ice) was commonplace. As plans for expansion were in progress, it became obvious that, to avoid damage from heavy snows and avalanches, long-span construction eliminating the need for poles along the sides of the steep mountains would be the best design (see Figure 18). It would require deadend structures with adequate strength to be designed and constructed. In addition, a method of deadending the conductors would need to be developed, since strain insulators as we know them today had not been invented.
To meet this challenge, multipole structures were designed and situated at key points on ridge tops where conductors could be deadended. The longest span was 1,100 ft. (335 m), constructed with no. 1 copper conductor supported by a 0.5-in (1.3-cm) plow steel messenger. The attachment of conductors was achieved with a unique inline crossarm arrangement attached to the structure with a large hinge-type bracket. The crossarm had 12 pin-type insulators mounted on wood pins, equally spaced in a row with the conductors, attached in a manner that distributed the strain equally between each insulator, a classic example of the foresight and innovation demonstrated by these early pioneers (see Figures 19 and 20). The original Telluride power line hinged crossarm shown in Figure 20 was found sticking out of a snowdrift high in the San Juan Mountains by Christian Buys, author of Historic Telluride in Rare Photographs. After seeing a photograph in the book, the author was able to arrange a trade, and the crossarm is now on permanent display at the Meridian, Idaho, campus of Northwest Lineman College.
Construction of the lines was a backbreaking manual effort, aided by teams of mules used to transport materials, tools, and supplies. Mules were also used for stringing the conductors and bringing them up to tension.
The maintenance and operation of these lines provided further significant challenges, as access to the lines was difficult, with heavy snows blanketing the area for several months (see Figure 21). Wisely, switching stations were established at key line junctions, where faulted sections of line could be isolated and service restored to the remainder of the system (see Figure 22). The design of the switching junction shown in Figure 22 featured a sliding wooden rack with insulators and contacts that was operated from an insulated platform. As was typical during these early years, the design was homemade, developed via trial and error. In this phase of expansion, the Telluride Power Company gained valuable experience in constructing and maintaining lines in the mountains.
Thinking about the pioneering days of the Telluride Power Company, one can only imagine how it must have been for these early pioneers, confronted with extinguishing electric arcs, fires, lightning, blizzards, ice avalanches, and –40 °F temperatures. To construct and operate a power system under these conditions with no experience is nothing short of amazing. The one element that was beyond the scope of this article, but equally innovative and important, was how the company conducted the training and education of its employees.
Once the Telluride Power Company completed a successful power system in the Telluride area, it immediately looked for other areas to expand the company’s operation as there was now considerable experience to draw from and a significant number of well-trained employees. They would continue to develop methods, materials, and procedures that would be marveled at by other companies. By 1905, the Telluride Power Company would own and operate six power stations and nearly 1,000 mi (1,609 km) of high-voltage transmission lines in Colorado, Utah, Idaho, and Montana. I plan to write a sequel that will cover the expansion of the Telluride Power System, along with the special training and education system that was developed. A trip to the San Juan Mountains and the Telluride area offers a multitude of recreational activities, in areas with breathtaking scenery. Mining and railroad history are everywhere, along with the Telluride Power Company. The Ames power plant has been upgraded over the years and remains in operation by its current owner, Xcel Energy. The plant can easily be driven to, with interesting interpretive signs along the way. The local Telluride Museum has a nice display on the power system. The town of Telluride has not forgotten its legacy of being a pioneer in the development of the electric power industry.
Northwest Lineman College has an in-depth display of the Telluride Power Company in the lobby of the Idaho campus, which features a mural of the Ames Plant and the line to the Gold King Mine along with photographs and artifacts from the line (see Figure 23). The college maintains a strong commitment to promoting an understanding of the historical evolution of the power industry. We include “a look back” in our training programs as we want our students to understand how we got where we are. Readers are encouraged to visit the campus if they are visiting the Boise, Idaho, area.
In conclusion, it seems appropriate to reflect on a statement made in the Annual Report of the Treasury of the United States in 1901:
For the growth of the mining industry, San Miguel County is indebted to the Telluride Power Company more than to any other agency, which is borne out by the fact that at the present time all of the important mines and mills of the district are operated by power furnished by this company.
For Further Reading
E. D. Cockins, Ralph Davenport Mershon. Portland, ME: The Anthoesen Press, 1956.
S. A, Baily, L.L. Nunn, a Memoir. Ithaca, NY: The Cayuga Press, 1933.
P. N. Nunn, ”Pioneering work in high-tension electric power transmission,” Cassier’s Mag., vol. XXVII, no. 3, pp. 171–200, Jan. 1905.
P. N. Nunn, “We did not know what watts were,” Gen. Electric Rev., vol. 59, no. 5, pp. 43–46, Sept. 1956.
C. J. Buys, Historic Telluride in Rare Photographs. Montrose, CO: Western Reflections Publishing, 2006.
R. Weber, A Quick History of Telluride. Colorado Springs, CO: Little London Press, 1974.
M. G. Wenger, Recollections of Telluride. Durango, CO: Basin Reproduction and Printing, 1978.
C. F. Scott, “High voltage power transmission,” Western Electrician Mag., vol. 23, no. 22, pp. 298–299, Nov. 1898.
Fort Lewis College, Center for Southwest Studies, Durango CO, Collection M002 Western Colorado Power Company Records. (Author’s note: The Western Colorado Power Company eventually took over the Telluride System in Colorado and all of the associated records. The collection consists of a treasure trove of documents and photographs that date back to the beginning of the Telluride Power Company. The author researched their archives in 2012 on a limited basis and found a considerable amount of valuable information. The research center Web site (http://swcenter.fortlewis.edu) has considerable information regarding the extent of the collection.)