Water plays a very special part in the creation of electricity. Hydroelectricity – when the power of falling water is turned into electricity, has been used for hundreds of years and is one of the most efficient ways to produce electricity. It's also good for the environment because it is a renewable energy source that has little environmental impact and does not emit greenhouse gases.
Hydroelectricity is an important part of NB Power's generation system. We currently have 7 hydro stations throughout New Brunswick, which accounts for half of all of NB Power's generation stations.
In a hydro station, water falls down a chute called the penstock and flows over the blades of a turbine. The falling water turns the blades, which are attached to the magnets by the generator shaft. The spinning blades turn the magnets, which creates electricity in the wire coils.
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The Mactaquac generating station is equipped with two generators capable of being operated in synchronous condense mode, units 5 & 6 on the west end of the station. Synchronous condense mode is a mode of operation used to supply voltage support to the system grid by operating units 5 &/or 6 as very large motors. To achieve this, the wicket gates are closed shutting off the water supply to the turbine and air is then injected into the runner chamber to depress the water level below the level of the blades in order to allow the blades to be turned freely by the stator/rotor assembly. At this point the units are running as very large motors and can be used to raise or lower the system voltage.
At any time, while these units are in synchronous condense mode, they may be reverted to generate mode, automatically or manually, simply by opening the wicket gates and passing water through the turbine again. The main consequence to the public, of this reversion of modes, is the fact that the large volume of air that was injected into the runner chamber is expelled when the wicket gates are reopened and this causes a large area of the tailrace in front of the unit to experience sever turbulence. If a boat were to be in front of a unit being reverted to generate the turbulence could be great enough to capsize or swamp the boat, putting the occupants in grave danger.
The units are equipped with a warning horn that will sound 30 seconds before the air is expelled warning anyone in the tailrace area to clear the area immediately. The best defense against being exposed to this danger is to never enter the tailrace area as it is a very dangerous area due to the constantly changing flow conditions and the possibility of severe turbulence.