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 )
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 Co, The
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."
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)
A map of the dam area, from a sailing
perspective.
From Michael McGoldrick.
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.
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.
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..
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.
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.
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.
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.
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.
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.
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.
Go back to the ELEC9706 page
Go on to Chat
Falls 2, 3, 4
Notes:
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.
Back
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.
Back
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)
Back
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.
Back
End of Notes
Go back to the ELEC9706 page
Go on to Chat Falls 2, 3, 4
