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el dispositivo para aumentar la velocidad. La p6rdida
de la eficiencia de1 dispositivo para aumentar la
velocidad varia de 1.5 a 3%. En este rango de la
caida hay disponibles en el mercado turbinas horizon-
tales. El costo de1 generador para una instalacidn
horizontal es menor que el de una instalaci6n ver-
tical, Con este tipo de caida se debe considerar tam-
bien turbinas con generadores protejidos en cajas im-
permeabilizadas y turbinas con el dispositivo para
aumentar la velocidad colocados en angulo recta.
En 10s cases en que la caida sea entre 60 y 120
pies, las turbinas a hklice y tipo Kaplan deben ser in-
staladas verticalmente debido a la mayor velocidad.
Las turbinas Francis operan a velocidades m& bajas,
no obstante para esta turbina se puede considerar
una instalaci6n horizontal. Es pr&tica corriente
limitar la instalacidn de la turbina Francis a unidades
con un digmetro de descarga de1 impulsor de 48’ o
menos.
Cuando la caida es de 120 a 1500 pies se puede
operar una turbina tipo Francis a velocidades
mayores que una turbina de impulso y 10s costos
seran menores tanto para la turbina coma para el
generador y la construcci6n de la planta de energia.
Cuando la caida es de 1500 pies o m&s se utiliza
una turbina a impulso. Para bajas capacidades entre
1000 kW y 5000 se debe considerar turbinas de
chorro horizontal simple o doble debido a la reducci6n
en 10s costos de1 generador. Por arriba de esta
capacidad las turbinas de cuatro a seis bocas son m&s
competentes. Las turbinas de impulso con m&s de
dos bocas de chorro se deben in&alar verticalmente.
En sintesis se puede ahorrar costos de1 generador
mediante instalaci6n horizontal y aumento en las
velocidades de la turbina. La velocidad de las tur-
binas de reacci6n es limitada por 10s parametros de
la cavitaci6n. El costo de la turbina y la reducci6n de
tamaiio es un tanto menor a altas velocidades; no
obstante el ahorro de1 costo de1 generador es
substantial.
Costos de la Turbina/Generador
Las Fig-was 1 al 7 contienen cuadros de costos
para 10s diversos tipos de turbinas-generadores. La
informacidn utilizada para preparar estos cuadros fu6
obtenida de 10s fabricantes de turbina, generador y
regulador durante 10s titimos cinco ties y reducidos
a un nivel de precio a julio de 1978. No hay listas de
precios sobre turbinas ya que la mayotia de las tur-
binas se disefian conforme a la necesidad. En
t&minos generales, 10s costos de turbina y generador
por kW instalado disminuye a medida que aumenta la
capacidad de la unidad. Adem&, la caida efectiva
187
this head range, horizontal turbines are available.
The generator cost for a horizontal setting is less
than that of a vertical setting. Turbines with
generators enclosed in a water tight housing and
turbines with right-angle drive speed increasers
in water tight housings should also be con-
sidered in this head range.
At head ranges between 60 and 120 feet, pro-
peller and Kaplan turbines must be set vertically
due to the higher speed. Francis turbines operate
at lower speed, however, a horizontal setting
could be considered for this turbine. General
practice is to limit horizontal setting of Francis
turbine to units which have a runner discharge
diameter of 48 inches and less.
At head ranges between 120 and 1500 feet, a
Francis-type turbine may be operated at higher
speeds than an impulse turbine and is more com-
petitive due to lower turbine, generator and
power house construction costs.
At head ranges of 1500 feet and above, an im-
pulse turbine is used. In the lower capacity
range, a 1000 kW to 5000 kW horizontal single jet
or double jet turbine should be considered due to
reduction in generator costs. Above this capacity,
four and six nozzle turbines are more com-
petitive. Impulse turbines with more than two
nozzles must be set vertically.
In summary, savings can be made in generator
costs by horizontal setting and increased turbine
speeds. The speed of reaction turbines is limited
by cavitation parameters. Deeper settings permit
increased speeds. The turbine cost and size
reduction is somewhat less at higher speed,
however, the generator cost savings are substan-
tial.
Turbine/Generator Costs
Cost charts have been prepared for the various
types of turbine-generators (Figures 1 through 7).
The data used to prepare these charts were ob-
tained from turbine, generator and governor
manufacturers over the past five years and
escalated to a July 1978 price level. Price lists
are not available on turbines as most turbines
are custom designed. In general, turbine and
generator costs per installed kW decrease as the
capacity of the unit increasles. However, the ef-
fective head available to the turbine has the
greatest influence on the cost. The lower the
head, the higher the cost per installed kW. This
increase is due to the larger size and lower syn-
chronous speed turbine required for the low head