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This dam in Chiapas

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is 261 meters tall,

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and the water it

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holds back drives

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eight generators of

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about 300 megawatts

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each.

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How does it work?

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The water drops

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through a penstock and

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reaches the spiral

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case,

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which spreads it

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around the turbine.

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The wicket gates open

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and close like blinds

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and control how much

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water gets in.

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The water pushes the

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blades of the Francis

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runner and leaves

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through the draft

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tube.

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There is no gearbox

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here.

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The turbine turns

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slowly at a few

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hundred revolutions

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and drives the

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generator directly.

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To make 60 hertz

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at that speed,

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the rotor carries many

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salient poles.

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For example,

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40 poles at 180

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revolutions.

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That is why a

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hydrogenerator is

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huge,

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like a disc several

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meters wide.

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The excitation feeds

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the poles through slip

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rings,

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and the governor moves

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the wicket gates to

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hold the speed.

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After decades,

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moisture,

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dust,

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and heat wear down

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the stator insulation.

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At TEMISA Power Gen,

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we diagnose,

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repair,

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and rewind generators.

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Get a quote at

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temisapowergen.mx