Canadian Niagara Power's ...
Rankine Generating Station
"100 Years of Power Generation"
One-hundred years of active service ... a claim few other generating stations could make! I was able to tour this gem of history during three visits, one an "Open Doors Niagara" event in 2003 in which numerous places of historical significance in the Niagara area opened their doors for tours, the second visit an IEEE sponsored event in 2004, and a third visit in 2008. As an engineer I was absolutely taken back with what I saw. Truly, walking into this place was like walking back in time 100 years to the dawn of the age of electricity where few places in the world had electric lights. Electricity, in those days, was 'The Magic Medium' and to many people, still accustomed to using coal-oil lamps in their houses for lighting, it probably seemed like magic. The generating station itself, built of limestone and featuring Italian marble and polished brass everywhere, speaks to an era where electricity was not simply a matter of utility - it was a new and expensive commodity and was treated as such. The mixture of technology, both old and new, architecture, and a total amazement at what they could do with manual labour and steam-powered excavators led me to write this page to share it with you. Enjoy!
Introduction: The Rankine Station
The Rankine station was, until 2006, one of the few 25Hz powerhouses surviving in the world. Until its recent shutdown, it was actively operating supplying industries in Niagara, on both sides of the border, with 25Hz power. During it's heydey, the plant was licensed to produce 100,000 hp (about 76MW) via it's eleven generators. In the early 2000's, the load for the plant, normally, was 40MW with 30MW supplied to Stelco in Hamilton for arc furnaces and 10MW to Washington Mills to operate furnaces there. Numerous small customers also utilized 25Hz power for everything from theatre movie projectors to elevators. In New York state, an estimated 85 customers (in 2004) still utilized 25Hz power. The future of 25Hz power was, of course, limited since the vast majority of loads in the region (both in Canada and in the US) were converted in the 1950's to 60Hz power. By 2009, the supply of 25Hz power will cease entirely. Still, the design of the plant provides insight into what could be accomplished with good engineering and relatively simple control systems.
The engineering that went into the plant was second-to-none (why else whould it have lasted 100 years?). Careful thought was put into every aspect of the plant from the water supply (including a forebay designed to eliminate the problem of ice buildup), basic electrical system (3-phase, new at the time and unproven in North America), the mechanical systems (with backup oil feed and backup water-cooling supply), and the control systems (using methods to synchronize alternators which were new at the time). Many parts of the plant exhibit cutting-edge engineering for their day.
This station was by no means the first to harness the power of Niagara Falls ... many previous attempts were made on both sides of the river ... but it was, at the time, the most significant given the immense size of the project as well as the fact that it used AC allowing the current produced at this facility to be transmitted over great distances. While it looks antiquated now, 100 years ago it was state-of-the-art and solved many of the engineering problems associated with earlier attempt to generate and transmit power on a large scale.
Background: Early Power Development
The earliest attempt at centralized power production (on a large scale) was by Thomas Edison in New York city in 1882. Steam engines drove relatively low-voltage DC generators primarily for lighting purposes. DC current cannot be transmitted for distances of more than a few miles so Edison envisioned a series of power plants located in and around large cities. This replica of one of Edison's coal-fired steam generating plants (the original, from Detroit, MI, circa 1888) sits in Greenfield Village in Dearborn, Michigan. No surprise, then, that earliest attempts to harness the power of the falls considered the use of DC current (endorsed by Edison) but this would have prevented distribution to Buffalo, 22 miles away, a large market for power (industrialized and with a population of 250,000 at the time). The limits of DC were soon realized, even for use within cities (imagine generating stations literally miles apart) and in 1892 Buffalo achieved the honour of being the first major city in North America to use AC power (Similar developments using AC power and long-distance transmission occurred in Germany in 1891). Steam plants, similar to Edison's DC plants in New York City, generated AC current for lighting (and so fewer were required since this power could be transmitted much further). The application of AC in North America began, in fact, in the Niagara area but long-distance transmission from the falls was still a dream until 1896.
More photos of the Edison Illuminating Company's Station 'A' taken at Greenfield Village in Dearborn, Michigan, where this replica (built in 1944, and one-quarter the size of the original) is preserved:
DC generators in the plant - in this photo the steam line is seen at the top of the photo driving the steam engine. A large belt drives the DC generator in the foreground (behind the fence) of which a magnet is visible. The magnet of a second generator is seen in the right wide of the photo.
One of the two large boilers - Dated 1887. The gas-fired heater in the photo (right of the boiler) is, of course, not original.
Henry Ford idolized Edison and with good cause: Ford was an employee of Edison's at the Detroit Station in the 1890's, eventually becoming chief engineer. Ford built his first car, the 'quadricycle' while still employed at the plant.
Power Production in Niagara
Development of power projects in Niagara began on the American side of the falls with the construction of the Scheollkopf plant and later the Adams plant. The Adams plant, owned by the same interests who would later go on to build the Rankine plant, was, in many ways, a prototype for the Rankine plant. Many engineering details, including the final adoption of the three-phase AC power system, designed by Nicola Tesla (of Tesla coil fame) were finalized in this project and the system became the prototype for electricity distribution projects worldwide. As far as standardization went, though, 25Hz - as employed on many of the earlier developments in Niagara - was adopted. In the Niagara area, power was primarily required for chemical industries as well as motor power - lighting was a secondary concern so the fact that 25Hz electric light flickered was of no particular consequence since this was only a small usage of the total power output. The original problem (leading to the adoption of 25Hz) stems from the fact that the turbines at the Adams plant were built before the adoption of AC was solidified - in fact at the time these turbines were installed it was not clear whether they would be used for the production of electric power at all or pneumatic (compressed air) power! Electricity was indeed a new thing in the late 1800's and it was not certain at all that whether it would become 'universal' or simply another passing fad.
The original turbines at the Adams plant, with their massive shafts, were designed to operate at 250 rpm (again, quite likely to drive pneumatic compressors, not electrical generators) and so 12 pole electric generators were envisioned which produced 25Hz to take advantage of the already-installed (slow) turbines. While many other places throughout North America adopted 60Hz as a standard (which was endorsed by the Westinghouse company, a prime supplier of AC machinery), Niagara's largest power project to date was going 25Hz. This set the 'standard' in Niagara which would remain so until half-way through the 20th century when the introduction of fluorescent lighting (which flickered much worse on 25Hz than incandescent lamps) was the final blow to the standard. On the US side of the falls, the Adams plant (owned by the Niagara Falls Power Company) generated two-phase AC and delivered 11000 volt AC current to the large Buffalo market via a 22 mile long route in 1896. It was, at the time, the most ambitious power project of its type. Buffalo, site of the Pan-American exhibition of 1901, was indeed power-hungry and the Adams plant would not provide an adequate supply of power for long. The Adams plant was closed permanently in 1961 and water diverted to the more efficient Robert Moses plant just North of the falls.
While power development proceeded on the American side of the falls, the first power generated on the Canadian side was in 1892 for the Niagara Parks River Railway. Three small turbines generated enough DC current (about 2 Megawatts) to run the electric trolleys which carried tourists through the area. The building was just to the north of the CNP plant outlined on this page and the plant was decommissioned in 1932 when the trolleys were removed and "the Boulevard" (the Niagara Parkway) was built to carry automobile traffic. It was demolished and today the main bus stop for the people-mover bus, just outside table rock, stands on that very site.
In the Niagara area, there is one older plant than the Rankine, the DeCew Falls plant located on the Niagara escarpment in St. Catharines. Operating in 1898, this plant produced AC current at 66.6 Hz (a first) and supplied power to Hamilton. The plant was bought by Ontario Hydro in 1930 and converted to 60Hz operation. It still operates today making it the oldest power plant in Niagara.
The Rankine Story
The Rankine story really begins in 1889 with the formation of the Niagara Falls Power Company in New York - the primary interests in the US Adams plant. Initial plans for this company were to produce electric power on the US side of the falls, eventually at two plants (the Adams generating stations). Logically, wanting to move into production of power on the Canadian side of the falls, a spin-off company called the Canadian Niagara Power (CNP) Company was formed in 1892. A site was leased from the Niagara Parks commission - eager to see development of the falls like that occurring on the American side - upon which the Rankine generating station was to be constructed, for $25000 per year (in 1892 dollars !). The agreement, designed to stimulate power production on the Canadian side, stipulated that construction of a power plant must begin by 1897 and by 1898 production of 25000 horsepower must commence.
Enter the Niagara Falls River Railway plant (above). In 1895 CNP signed an agreement with the railway company allowing the railway company to sell surplus power for three years after which CNP would supply power to the railway. Prospective customers of that power included the Niagara Falls Electric Light Company and the Carmellite Fathers Hospice. By 1897 it became evident that CNP could not meet the deadline for development as the American arm of the company wanted to complete the Adams plant first (from which transmission of power to Buffalo began in 1896). The Adams plant supplied two-phase 2200V local service as well as three-phase service to Buffalo via 11kV lines (two-phase power, produced by the generators, was converted to three-phase by a 'Scott Transformer' and sent to Buffalo that way). Completion of the Adams plant first allowed the working-out of technological 'bugs' like lightning arrestors and switchgear before starting construction of the Canadian plant. While technology for the American plant was developed 'on the fly', as evident from the use of 25Hz generators to take advantage of already-installed turbines, it was hoped that the Rankine plant would be planned better from the beginning (although 25Hz was still to be used here since it was now 'standard' in Niagara). In a stop-gap measure CNP proposed that it install more generating equipment into the railway generating station allowing CNP to fulfill its contract. Only two 425 hp generators were installed with an excess capacity of 300-500hp available for customers. The railway plant was now generating both AC power at 2400V and DC power for the railway. It was the first plant in Queen Victoria Park and an agreement with the government of Ontario allowed CNP to continue its monopoly at this time.
Not surprisingly, local officials in Niagara Falls were upset at the apparent lack of (promised) investment in power generation - the whole idea of the agreement in the first place was to develop the Canadian side of the falls into a major power production center, with the ultimate goal of providing power to the large city of Toronto. By 1899 it was obvious that CNP could not supply power to Toronto (the CNP had not even started construction of the Rankine plant) and CNP's monopoly to produce power at the falls was lost allowing other companies to produce power. Not surprisingly a great deal of politics were involved. In all fairness to CNP (and the parent Niagara Falls Power Company), the intent was to complete power projects on the American side first to ensure capital was not spread too thinly. There were also enormous technical difficulties to overcome in the system of transmission of the power to the intended loads in Toronto - sending power from Niagara to Buffalo is one thing (and was, at the time, a milestone), but Toronto is considerably further away.
Buffalo was always seen as the primary market for Niagara power, though. The site of the 1901 Pan-American exhibition, Buffalo was fed from the Adams plant early in the century. To help feed the power-hungry city, power from the railway plant on the Canadian side was fed via cables along the upper arch bridge in Niagara Falls was sent to the US side. 1000 hp of three-phase power at 2200 volts was sent across the bridge but that, too, was not enough to satisfy the needs of the growing city ... the Rankine plant would hopefully fill that need soon.
The Rankine plant, started in 1901 and completed in 1905, was the first major power development on the Canadian side of the falls and at the time, the largest generating plant. It would soon be joined by other power plants, though ...
Competition ...... even before the race had begun!
With the monopoly on power production gone, other major power projects around the area included the Electrical Development Company's (aka the "Toronto Electric Company") generator just to the south of the CNP plant on the other (water) side of the parkway. Ready at the end of 1906 (after the Rankine plant was already producing power), this plant generated 75 Megawatts of power destined for Toronto. Water drawn from the river powered turbines in the station and was discharged through a tunnel (actually, two tailrace tunnels) leading behind the horseshoe falls. The tunnels were built of concrete rings so that as the falls recedes, these rings would fall into the river below instead of leaving a concrete structure protruding from the falls! This station was decommissioned in 1973 but the building is still intact on the west bank of the Niagara river today. The building is currently unsafe with portions of the roof collapsed due to neglect. In past years, parts from this old generating station have been scavenged for use at the Rankine plant as spares.
A pamphlet describing the Toronto Power Plant (received from a visitor to this site) circa 1930 and reprinted in 1982:
Front of the pamphlet describing capabilities and featuring a photo of the generator bay.
Inside of the pamphlet describing the plant and how it is part of the Ontario Hydroelectric system.
In 1905, a plant built by the Ontario Power Company (another private concern) was opened under what is known today as table rock. The OPC unveiled its planned station in 1900 and began construction in 1902. Water from above the falls near the Dufferin islands (the gate house is just south of the Toronto generating plant) is carried via two large-diameter pipes to the plant just below the falls which produced 25Hz AC current like the CNP plant on this page. Two large surge tanks, one still intact today with the battery of lights which illuminate the falls each night mounted atop it, were used to smooth-out water flow as usage in the plant below changed. This plant has been mothballed by Ontario Hydro (which took over the plant early in the century).
Shortly after the first decade of the century new power projects were declared to become public property and water rights were no longer granted to privately-owned concerns. All further development of hydro-electric projects, including the two huge Sir Adam Beck stations north of the falls in Queenston, was done by the government-owned Ontario Hydro Company. The DeCew, Toronto Power, and Ontario Power plants were eventually bought by Ontario Hydro - only the Rankine remained as a privately-owned power plant.
While the delay in building the Rankine plant proved costly to CNP, in terms of losing its monopoly on power production, to also gave them time to overcome technical obstacles. By 1902, a year after construction of the plant began, the problem of transmission of power (to Toronto) was solved. Based on work done at the US Niagara Falls Power Company plants, transmission was accomplished by stepping-up the voltage to 60kV using transformers built by the Canadian General Electric Company (Remember, too, that this was a scant 14 years after Edison's Pearl St. DC plant so AC technology had developed an amazing amount during this short time period!). The transformer house for the Rankine plant still stands today on Portage road across from Marineland, atop the bluff behind Victoria park - a separate transformer house was necessitated by the agreement with the Parks commission that prohibited unsightly overhead wires. On January 2, 1905 the Rankine plant began producing power with two 10000hp alternators. Those alternators, originally pegged at 5000hp each, were also subject to improvements and were upgraded to 10000hp each by the time they were installed. Power was utilized by both Canadian customers as well as in Buffalo, fed by lines running to Fort Erie and across the Niagara river. The use of AC current allowed transmission over great distances but the Canadian route was still advantageous since it was only 16 miles long and hence shorter than the US route.
The total cost of the completed plant was $5.2 million (in 1924 dollars).
A map showing the historical generating stations immediately around Niagara Falls. Water from the Niagara river flows from the left to the right. The first plant, the EDC (Toronto Power) plant is on the far left and the OPC plant at the base of the falls is on the right. Most of these structures, except for the Park & River Railway plant, can be seen from space on Google Earth.
As a backgrounder, might I suggest the following web links ...
Fortis Ontario web site, the parent company of Canadian Niagara Power which owned the station
The Day They Turned The Falls On another excellent overview of power projects in and around Niagara Falls. Focuses primarily on early stations on the US side including hydraulic and pneumatic approaches.
The Hydraulic System of the Rankine Plant
We begin by examining the hydraulic system consisting of water gates, massive pipes to carry the flow, and turbines. As well, this section outlines the shaft used to spin the alternators on the station floor over 130 feet above the turbines in the 'wheel pit' below the plant.
Water from the Niagara river enters the forebay to the plant just above the horseshoe falls, the top of which is visible in the upper-left side of this photo. The Niagara Parkway, which runs parallel to the Niagara river, passes over the forebay as seen in this photo. The original placement of the Rankine plant was on what was known in 1900 as Cedar island - this was to take advantage of the natural flow of water towards the island, on which the plant was to be built. Water channels behind the island were filled-in and what was once an island became a part of Queen Victoria park. The five-arch bridge was originally designed to carry the electric trolley cars used by the Niagara Falls Park and River Railway Company to carry tourists around the falls. Water is channeled into this entrance by a submerged weir visible only as a change in the current of the water.
Water then slows and settles in the forebay, to a speed of six feet per second, and deeper water in the forebay, free from ice, is drawn into the powerhouse through a series of submerged arches. Ice, floating atop the pond, is swept away down a small canal to re-enter the river.
Ice has always been the achilles-heel of generating stations at Niagara and the Rankine plant used an icebreaker boat and even dynamite to clear the forebay from ice build-up. One of the advanced features of the forebay was indeed the ice sluice which routed broken-up ice back to the river where it went over the falls. Other plants, notably the OPC plant at the base of the falls, were considerably more susceptible to ice problems.
The architecture of the plant with its huge arches and limestone construction, hardly detracts from the esthetic beauty of the falls. Huge copper doors on the other side of the plant elude to the grandeur of the building and the status electricity once had in the dawn of this era.
Taken from the roof of the plant, the ice raceway at the north end is visible here. Ice, floating atop the pond, is swept away down this small canal to re-enter the river just before the horseshoe falls itself.
Water in the forebay then passes under the arches, visible here as a green glow under the water, and through metal grates which remove debris and remaining ice before passing through the control gate (called a head gate) and onto the turbines. Stories from CNP employees tell of workers on the night shift fishing in this area of the plant and even of a five-foot long muskie traversing the forebay area in search of smaller fish to eat!
The massive head gates, one per turbine, control coarse water flow and are used as shutoffs for each pentstock. At one time manually controlled, these gates are now controlled by servo motors above the gates. Massive screws on either side of the gate operate it. The gates were opened slowly to allow the pentstocks to fill with water and displace air ... opening a gate too quickly would result in a massive air bubble coming back up the pipe and knocking access covers open. Once the pentstock was full, the gate was raised to a completely 'open' position.
Water then flows past the gate down the pentstock to the turbines located 136 feet below in the wheel pit. The pentstock is 10 feet, 2 inches in diameter. This photo, taken from the floor of the station looking down into the pit, shows the elbow where water is diverted downwards to the turbine below. On the larger photo of the station floor (seen later on these pages) this photo was taken down one of the grates labelled 'Pit Access' used when maintaining the turbines below. The walkways visible in the photograph are below floor level and used to access bearings supporting the massive shafts.
Pentstock Tube the large dimensions of the tube are evident in this photo of the bend in the above pentstock as taken from one floor below grade.
The original speed governor was based on two fly-balls as seen here. As the speed of the shaft increased centripetal force makes the weights fly outward moving a small shaft up and down underneath. The up/down motion of that shaft is amplified by a hydraulic system in which a pilot valve controls the flow of oil into a hydraulic cylinder. The torque is amplified by two sets of levers (one on the floor immediately below the alternators and the other at the bottom of the wheelpit) and eventually pushes a large rod connected to a ring valve on top of the turbine which actually controls the flow of water into the turbine. The faster the shaft turns, the more the valve is closed restricting water flow and slowing the alternator. An elegant, and simple, mechanical system for controlling the speed of the alternators which must be precise to allow units to function together.
The ring valve controls the actual water flow. It operates by sliding an outer ring against an inner tube (like the venturi on a natural or propane gas burner). Visible in this photo is a large lever which operates the valve controlling position. The turbine is immediately beneath the valve.
In the wheel pit, water from the pentstocks spins turbines. Water from above makes a sharp curve and enters the turbine from the side, exiting in the middle. A long shaft, supported by two bearings plus one thrust bearing, carries mechanical energy upwards to alternators on the shop floor. The shaft is 40 inches in diameter in most sections to prevent twisting. Water passing through the turbines falls into a 25 foot high discharge tunnel below which carries it to the Niagara river below the falls, a distance of 2200 feet away. The discharge tunnel is visible, on weekdays with water flowing from it, just north of the 'Journey beneath the falls' attraction.
One turbine, the last one installed (unit #11), is an advanced variable-pitch turbine which acts like the blades of a helicopter. This arrangement provides precise control of speed as well as high efficiency. This efficient turbine, coupled with an equally efficient and advanced alternator (it was the last unit installed) produces twice the output of any other single unit in the plant.
The heavy shaft is supported along its length by two bearings and at the top by this thrust bearing. Located one floor below the alternators this massive bearing is immersed in oil inside the housing seen here and supports the weight of the shaft. Oil is stored in tanks in the roof of the plant and is gravity-fed in a fail-safe scheme ensuring adequate lubrication of all bearings. Should oil flow fail, the bearing would rapidly seize. The outer bearing case seen here contains a large number of copper tubes on the inside, in contact with the lubricating oil, through which cooling water flows. Failure of cooling water was the biggest concern and to protect against this, a reserve tower was erected at the site of the transformer station on top of the ridge behind the plant. Should cooling water fail, gravity would feed water from the tower to parts of the plant below. The reserve tanks held 24 hours of cooling water supply.
A look down one of the access covers to the wheel pit below shows just how long the shaft really is! The turbine itself is visible at the bottom of the pit and the long shaft, with support bearings, is seen rising to grade level.
This photo was taken from the thrust-bearing level, one floor below the generators, so the thrust bearing is not visible here (it would be right in front of you).
Thrust Bearing Casing showing water cooling lines inside. In the background the actual metal pieces for the bearing plates can be seen.
Shaft Bearing showing the large, hollow shaft leading to the alternator as well as the narrow section held by the bearing. The ladder in the background should give a good idea of the size of the shaft (remember, it carries 10,000 horsepower!).
Shaft Brake just under the alternator, this brake is used to hold the shaft from spinning. It cannot be used to stop or slow the alternator but is simply a holding brake.
When it first opened in January of 1905, only two generators were in operation. By June 1924, all eleven generators were installed in the plant, with a capacity of 10000 hp each for the early units. This photo of the nameplate, taken from the rotor of an actual generator (by crawling through the access pit normally used for inspection, immediately under each unit) shows the capacity of the unit: 12000 volts at 500 amps per terminal, 3 phase at 25 cycle, with a total output of 10.4MW.
The Control System
Of course there is more to power generation than simply spinning an alternator ... there is a huge issue around controlling it. First and foremost, before AC alternators are placed in parallel on a grid to generate power they must be synchronized both in output voltage and in phase. To this end, power stations often use elaborate computerized controls but not 100 years ago! This particular plant is a unique blend of old and new technology with several units utilizing modern controls and others relying on the operator at the plant to manually synchronize the alternators.
Metering for each alternator consists of monitoring the reactive VARs of the machine, output in megawatts, output current and output voltage. As well, a meter displays the freqency of the machine's output - in this case 25Hz as expected.
Synchronizing an alternator to the bus is accomplished using a 'clock' (really, a phase meter showing the difference between two separate phases) and a manual breaker which connects the alternator to the bus. The operator inserts a six-pin plug into the socket shown at which point the 'clock' lights orange and begins to rotate to indicate the difference in phase between the bus and the alternator. There are three 'clocks' in the plant, two in the control room and a third visible from the plant floor. The operator then attempts to make this difference as small as possible (by controlling speed of the shaft) and when the phases coincide as shown by the clock (at 12:00), the breaker on the floor is activated connecting the alternator to the grid where it will self-synchronize to the phase already present. In olden times, this was accomplished by an operator on the shop floor who turned a wheel on the governor system beside each alernator to regulate its speed as closely as possible to the target - today it is done from the control room. If the breaker is connected at the wrong time, a massive arc results in the breaker occasionally causing damage to the system and certainly scaring anyone within earshot! Obviously, synchronization is preferable before the breaker is closed!
This panel shows the controls for two alternators. Unit #5 is actually online (the only unit running on the quiet Sunday morning of my first visit in 2003). The breaker control is set to CLOSE to connect this alternator to the grid. Unit #4 to the left is on standby in this case. When required (as load increases) it can be brought onto the grid by synchronizing it and closing the breaker. Some controls are modern while others like this are fully manual. Many of the older units sported knife switches to close the breaker circuit in this control room.
Aside from alternator breakers other controls on the panel allow the operator to route and monitor power to various lines exiting the plant.
Additional Controls showing a newer breaker control on unit #11. Controls such as these connect the 11 generating units to one of a number of internal busses as well as switch these busses to the grid leaving the plant.
Rear of the Switchboard The entire switchboard is designed as a large semicircle in the room - the inside facing the control desk and the outside covered in additional controls. Visible here are controls on the outside. In the background, the blue box holds an inverter used to produce 60Hz power for newer controls.
Massive breakers on the station floor route power from alternators to busses within the plant and from those same busses to the grid outside the plant. Actual bus-bars are housed under the floor of the plant in a corridor running under the breakers, with the stairway leading down to that corridor featuring appropriate warnings about high voltages. Peaking through down the stairs one can see large copper bus bars mounted on white ceramic insulators mounted on the walls. These breakers, apparently General-Electric FH-type, are mechanical as seen here, with the three arms corresponding to each phase to be switched. A motor, along with a large spring, operates the contacts which close with great force (and in a minimal time) resulting in reduced arcing, and hence reduced damage to the contacts. Opening the breaker is accomplished in a similar manner. Breaker contacts themselves are immersed in oil to quench arcing upon opening and closing and required periodic maintenance such as burnishing the contacts.
The breaker does have a finite operation time (the "open" time is rated at about 0.2sec) and so the operator would have to anticipate the correct time to close the breaker based on the speed at which the synchro-clock was rotating (i.e. predict "zero" at which point the phases of the alternator and the bus are coincident).
DC M-G Set a motor-generator set within the plant which runs from 25Hz and produces DC current used for control systems. All alternators require DC current for excitation of the rotor and controlling this field also controls the output of the machine. Originally, DC generators to run the exciters were located in the wheelpit of the plant (far below floor level) with their own small turbines. The overhead crane, used to lift the 70 ton rotors from the alternators, runs from DC as well.
At one time, speed of individual alternators was controlled by spinning-ball type regulators of the type seen in the foreground here as well as in the above section on hydraulics. Most alternators have been upgraded to include a computerized system for regulating speed which controls ring valves directly via servo motors instead of the hydraulic system once used. In this case, many parts of the original control system are intact - in the floor under each alternator there still exists a large lever connected to the ring valve many floors below. Where a servo is used, it operates the lever directly instead of a small pushrod from the governor on the plant floor above as employed with the older system. (I was told, BTW, that the original ball-governor system worked better than the servo system since it allowed quicker starting of the shafts than the servo system ... quicker starting meant less damage to the thrust bearings).
As well as speed, exciter current (the current supplied to the rotor to generate a magnetic field for the alternator) is computer-controlled giving tighter regulation of alternator voltage. Parameters controlled for each alternator unit include speed (regulated by ring valve position) and output voltage (regulated by exciter current).
Future of the Plant
During the 1950's all of Ontario was systematically converted from 25Hz power to 60Hz power. Trucks like those shown here came through each neighbourhood converting motors to the new current. You'll note here the sign on the truck "60 cycle power for progress". Aside from the fact that lights flickered noticeably at 25Hz (and don't at 60Hz), transformers and other equipment operating at 60Hz are much smaller (this is also the reason why aircraft use 400 Hz systems - the size and weight of electrical equipment are reduced drastically over 60Hz). My parents still have a fan from the early 50's with a '25Hz' label on it. A second label states that the motor was rewired for 60 Hz. Of course only motors were affected by the change and in the 1950's there were much fewer motors and appliances than there are today.
Laws written many years ago compelled power companies to continue production of 25Hz power so long as there were customers requesting it. This arrangement has lapsed and with it, the demand for the production of 25Hz power. As of 2003 there were still a number of industries using 25Hz power such a Stelco in Hamilton (for electric arc furnaces) which have not yet converted to 60Hz power.
The efficiency of a plant operating this close to the falls suffers from a much smaller drop than generating stations operating down the river (like the Beck stations). A larger drop yields more kinetic energy and hence power generated per gallon than a smaller drop and since there is a finite amount of water available at Niagara Falls for power generation (limited by a treaty between the USA and Canada designed to keep ample water flowing over the falls), efficient use of water resources is a prime concern nowadays.In 2003, the plant was on 'standby' status and was still used, primarily on weekdays, to generate power for industries. In addition, the plant generated power when excess water capacity is available which cannot be entirely used by the other OPG (Ontario Power Generation) plants in the area such as Sir Adam Beck 1 and 2. In 2005, after 100 years of continuous power generation, the plant officially ceased generating power. Water once consumed by the Rankine will be diverted to the Beck plant in Queenston, Ontario, via a third large tunnel currently being drilled under the town of Niagara Falls (another interesting achievement - search this one on the web). CNP had signed-over it's water rights to OPG and water which once flowed through the Rankine plant (as well as others at the top of the falls) will flow to the Sir Adam Beck plant in Queenston where it will generate even more power.
During my first tour of the plant in 2003, on a quiet Sunday morning, one alternator was active and generating more than enough power for customers on the grid at that moment. On the second tour of the plant one alternator was spinning, but curiously, no water was flowing! The alternator was 'motoring': An alternator such as this can be run as a wound-rotor motor. Fed from the 25Hz grid (powered primarily from the large frequency-changer at the Sir Adam Beck 1 plant down the road at this time in the week), the alternator was kept 'warm', synchronized, and ready to operate immediately. Part of the agreement CNP had with the market operators was to be able to supply power to the grid at a moment's notice so it was important that at least one unit always be in a ready state. I was also told that during the winter months electric current is circulated through idle alternator's windings to keep them warm and free of condensation: 13.8kV and moisture don't mix well! During my last visit in 2008, all generators were kept in operational condition in this manner (to preserve them from damage) .... even with the plant mothballed, CNP is still taking care of this gem!
By 2008, all generators were silent and 25Hz power, supplied via the frequency changer at Beck-1, was used to power the sole CNP client still consuming 25Hz - Washintgon Mills. This power was routed through the 25Hz grid via the Rankine station which was still used as a distribution and control point for the 25Hz grid.
As of 2009, 25Hz generation ceased entirely and the 25Hz grid will be shutdown. As for the Rankine plant: in April of 2009 the lease is up and the plant and the land it sits upon will revert to the Niagara Parks Commission (NPC). The NPC is currently looking towards potential future uses for the plant one of which, I think all people who have toured this plant agree, would be a museum as a monument to the golden age of electricity!
For further interesting reading on the Rankine and the history of the Canadian Niagara Power Company I suggest the excellent book The Canadian Niagara Power Company Story by Norman R. Ball (Boston Mills Press, 2005, ISBN 978-1-55046-462-7).
I hope you enjoyed this rare tour of a 1900's generating station. A professor at Niagara College in Canada, my personal interests extend to the history of technology, hence why this place was so intriguing! If you have any comments, you can contact me via the link in the left column of this page. Please refer to the 'Rankine' station on the subject line.
Other tours of Niagara generating stations on this site include the Sir Adam Beck 1 Generating Station, an old 25Hz station from 1922 which has undergone a complete update to 60Hz as well as the Decew Falls Generating Station 110 years old and still operating in Niagara. This plant has the distinction of operating at the relatively high frequency of 66.7Hz in a time when other plants were running at 25Hz.