ABOUT THE TOWN

Chronicle (Levin), 2 November 1946, Page 3

ABOUT THE TOWN

T. S.

D.)

SHANNON SIDE-LIGHTS

(By

A f ugitive scientist from a Boris Karloff horror picture dreamed about a serum that-'wquld bring irianimate objects .to life. He surreptitiously tried it , out on the statue of a general in a park.' The statue gave a shiver and-a moment later the general, creaking a bit in the joints, cljmbed down from his pedestal. The scientist was overjoyed. "I've given you life," he exulted. "Now tell me, General, what is the first thing you are going to do with it?" "That's easy," rasped the general, ripping a gun from his holster. "I'm going to shoot about two million pigeons." The Mangahao Hydro Scheme In this, the concluding article of the Mangahao hydro electric scheme, we intend to deal with the power house. This building, a substantial reinforced structure, is built on solid rock foundations. Including the foundation, 8000 cubic yards of concrete and 244 tons of steel reinforcement were used in its construction. At the entry of each pipe into the power house there is a valve operated by the water itself. Each pipe supplies water to a Pelton wheel, which is coupled to a generator. The function of the Pelton wheel is to use the velocity of the water for transmitting .mechanical energy through the turn of the shaft to the generator, which in turn transforms the mechanical energy into electricity for use at a distance from its source. The generating plant consists of three generating units of 7500 horse power each, and two of .3750 horse power each. The air for coolmg the generator is taken from the basement and drawn through the generator, by the suction set up by a fan acting on the generator rotor, and then discharged i-nto the generator room. The electric power is generated at 11,000 volts and is taken from the machines in lead covered cables to the 11,000 volt switchgear, which is situated on the same floor as the generators. The operation of all the switchgear is done electrically from the switcliboard gallery. On this floor are situated the main controis, instruments and relays etc., for measuring the power and protecting the equipment. The small machines iri the centre of the generator floor are ihe exciters for supplying direct current electricity to the large generators, battery and other apparatus requiring direct current electricity. The high tension telephone exchange, which terminates the telephone lines in connection with the transmission lines, is also situated on this floor in a sound-proof cabinet. At one end of this floor is situated the battery room, in . which the battery used for operating the switches, etc., is housed. At the other end are the offiees. The greater portion of the power generated is transformed from 11,000 volts to 110,000 volts for transmission. The transformers are in two banks of 15,000 horse power each. They are six in number, and there is also a seventh transformer as a stand-by. The function of the transformers is to change the electrical energy from 11,000 volts to 110,000 volts, as it is easier to transmit large blocks of electrical energy to a greater distance at the higher voltage. At the far end of the transformer floor is situated the oil s.tore, where the oil used in the transformers and oil switches is stored and purified. After passing through the transformers, the current, now at 110,000 volts is led up on to the high tension floor. On this floor ,are situated three 110,000 volt oil switches,' air break switches and bushes. At the other end are also situated the 11,000 volt induction regulators, which control the voltage for the supply of the Horowhenua Power Board. The other end of this floor is used as a store room. From the high tension floor the current is led through porcelain bushings On to the roof. Here are situated the oil switches which control the outgoing 110,000 volt lines. Two lightning arrestors are also placed on the roof. The functions of these are to discharge excess charges of electricity set up in the high tension lines by lightning, and thereby protect the valuable electrical equipment in the power house. From the roof of the power house lines go north, south, east and west to the various sub-stations, where the electrical energy is received at 110,000 volts. The functions of the sub-stations are to again transform the power down to 11,000 volts, at which pressure the energy'is supplied to the power boards, who in turn transform the energy from 11,000 volts to 400 and 230 volts for the use of the various consumers connected to the board's lines. Electric motors and similar apparatus are operated from the 400 volt supply, while the ordinary household equipment, such as lights, irons, etc., are conhected to the 230 volt supply.