The Ontario Power Generation Corporation's
Chat Falls Station,  page 1

The correct technical comment in these files are by Carl Kroop, any errors were additions by John Knight.

Chat Falls Hydro-Electric Plant on the Ottawa River. (From OPG and Hydro Quebec )
ChatsFalls Aerial View

power house

The plant is jointly owned by the Ontario Power Generation, who owns units 2, 3, 4, 5 (24 MW each) and Hydro Quebec, who owns units 6, 7, 8, 9). 
These generators were installed in 1931/32.  If history interests you, look at the IEEE  history of power in Ontario  or OPG Chat Falls.
If you would like a power stations for dummies type explanation try How Stuff Works, Wisconsin Valley CoThe Foundation for Water and Energy Education, or the US Dept of Labor.

View downstream (north) from the powerhouse. The word "Chat"  is pronounced chaa  as in the French word for "cat."
Downstream view

General properties of  the station

It is a  run-of-river or flow through generating station where the power is supplied directly by the river and there are virtually no reserves. Hence the power varies depending on the river flow.

The head is 16.16 m.

There are two generators, at Adam Beck (Niagara Falls) and Chat Falls, that can "blackstart" (They can start generation without a power grid connection). In the North-East blackout of August 14, 2003, these islands of power, and the Saunders (Cornwall) station, provided a base, for the IMO to start the recovery of the other stations.

Chat Falls is connected to:
- Arnprior,  Barrett Chute, Chenaux, power stations in the Arnprior-Refrew area
- Paugan in Lowe QC by a 230 kV transmission line.  (Quebec tie lines)
- Toronto via a  230 kV transmission line
- Ottawa via a 115 kV  line
- Ottawa (Merrivale Station) - Toronto via a 230 kV line.

The Hydro system surrounding Chat Falls, (from the Swiss Federal Institute of Technology, Lausanne)
Ottawa River Drainage and Hydro Power Basin

A map of the dam area, from a sailing perspective. From Michael McGoldrick.

Sailing map of Chat Falls  The river is flowing north here.
 The dam  extends along the banks
on the south.
For an larger scale overview,
see the large sailing map.
or the Ottawa City air photos.

Below is the Hydro Quebec view of Chat Falls (Chute des Chats).  As shown in the original, the north side is at the bottom in this map, so mentally invert it to agree with the sailing map. The capacity of 89 MW is for the half of the station owned by Hydro Quebec.

legendHydroQuebec Chute des Chats     

An  alternate map, which is not upside down, is the Google map. The line map is not as clear as the sailing map and does not show the complete spillway or the long Quebec arm of the dam. The Ontario part of the spillway looks like a wharf.  However the satellite map shows the dam clearly.

The switch yard: The two round cylinders half-way up on right are line-traps for power-line carrier.switch yard lines and carrier filters

Circuit Breakers  Three single-phase circuit breakers are in the bottom centre, Single-phase breakers allow one to do single-phase interruption which helps maintain stability in a single line-to-ground fault. Opening one line may clear an arc, leaving two lines to maintain synchronization.  To make a rough identification of switchyard components see Emerson's descriptions..
circuit breakers

The cylinder with 3 big insulators sticking out is a 3-phase gas (SF6) or vacuum circuit-breaker.  The vertical tan cylinder near the bottom middle is probably a potential transformer, used to reduce 115 or 230 kV down to more palatable level for measurements.
Another look at typical switchyard equipment is in component pictures.
3-phase breakers

Three single-phase transformers. They step-up from the (13.8 kV?) generation bus to the 115 or the 230KV transmission lines; an experienced lineman could count the petticoats on the insulators and tell you which high voltage. The transformers are water cooled (no  fins). On the far right you can see one newer air-cooled transformer.
Three single-phase transformers

A better view of the air-cooled transformer. Note the fins on the side. The tank on the top is the oil conservator tank. There is N2 on the top half of the tank, so the oil will not be oxidized. The space in the tank allows the oil to expand without breaking the casing. On the far right is part of another air cooled transformer of a different style. The flat side of the fins is facing you.
Air cooled three-phase transformers

The station generator floor: A small dc generator, the pilot exciter, is on the top of each generator. This supplies power to the larger dc generator below it, the main exciter. The pilot exciter is effectively an amplifier; it's relatively small field current controls the larger field current of the main exciter, which controls the large field current of the 3-phase generator. This is old technology. The fields in newer generators, are controlled with semiconductor circuits..
The generators are each 24 MW (32,200 HP). Older machines were rated in HP, newer machines in Watts.
Carleton student's touring the station.

A generator- turbine The FWEE gives a generator diagram as shown on the right:
(1)  The powerhouse.
(2)  The thin red cylinder, just below the (2) is the exciter which provides dc for
       the electromagnets in the rotor.
(3)  The rotor which consists of  40 or so electromagnets, the poles of which point
      outwards. N and S poles alternate, causing the field to change polarity
       120 times per second.
(4) The stator is made of stationary coils of wire. Electricity is produced as the
       rotors spin past these coils.
(5)  The main thrust bearing on the shaft. In the Chat Falls generators this bearing
       is of a type called the Kingsbury bearing, and  is between the the excitor (2)
       and the rotor (3). Not where it is shown here.
(6)  The wicket gates are a series of 20 or so adjustable vanes, resembling vertical
       blinds. They control can adjust the volume of water flowing through the turbine.
(7)  The turbine.
       There were no pictures taken of the turbines at Chat Falls.  This one looks
       like a Kaplen turbine. A good description of the common water turbines is
       in the Wilkipedia, or at Simens.

On the very top are service lights. Below that the pilot exciter (with ventilation holes), then the main exciter with its commutator (the next two sections with ventilation holes).    On the bottom is the main thrust bearing, the "Kingsbury bearing,"  which floats on an oil film.
Top of generator with exciters and main thrust bearing.

The very bottom of the main exciter and the Kingsbury thrust bearing. This bearing holds up the whole machine including the weight of the water which is turning the turbine. There is a pressure drop across the turbine which is mainly the weight of the water, hence this bearing holds more weight than just the 200 tons or so of steel and copper.
Kingsbury bearing

The generator with the field (rotor) removed, leaving the stationary part, the stator. This stator is what is connected to the external 3-phase generator bus and then, through the transformers, to the power lines.

The stator again. You can see the large wires which make up the windings. The black oval around the edge of the pit floor, is the top of the wicket gates. Below that oval are the gates that control the water flow through the turbine. The water flows directly under the floor in the bottom. The holes around the pit let outside cooling air come in. There is quite a draft if you stand on the stairs shown when the machine is going.


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Now big is 24 MW?
Each generator is 24 MW (megaWatts). That gives 24 MW * 360 days * 24 hr =  207360 MWh/year
A typical house uses 3MWh /year.  Thus each generator can supply about  69000 homes.
All eight generators could supply  1/2 million homes on average. However this does not say it could
handle peak loads without help.  Better take the Carleton course ELEC4906 to find out more.

Equipment pictures from US Dept of Labor. They have a large glossary of power and EE terms.
Air Circuit Breakers
Bus Support Insulators
Circuit Switches
Current Transformers
Potential Transformers
Lightning Arresters
Oil Filled Circuit Breakers
Power Transformers
SF6 Circuit Breakers  Sulfur hexafloride is a gas with a very high breakdown strength.

Weight of the water
The thrust of the water in tons is T = K*pi*(D2/4)*H/32
   K is a thrust coefficient which we will take as 1.
   D is the discharge diameter in feet (estimate as 20 ft {16.1 m})
   H is the turbine head in feet (53.0 feet {16.16 m})
Then T = 520 tons (472 metric tonnes, 472,000 Kg)

Oil Film Control
Kingsbury Bearing Oil Control in the Island Falls Station on the Churchill River. This give you some idea of the complexity of maintaining the oil film in the thrust bearing.  The bearing is shown as the upper guide bearing and the lower guide bearing, separated by the generator floor.Oil control system

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