"ELECTRICAL BRAINS"

Evening Post, Volume CVII, Issue 146, 21 June 1924, Page 8

"ELECTRICAL BRAINS"

THE NEWTOWN SUBSTATION

AUTOMATIC FIRST AND LAST

FIRST OF ITS KIND IN AUS

TRALASIA.

Though citizens have seen really fewsigns of it beyond the cutting up and sometimes recutting up of streets and the laying down of immense armoured cables, the transport of strange ■ looking rcachinery, and so on, very great electiical developments have taken place in the city during the last two or three years, and to-day .these are reaching finality. Evans Bay is an accomplished fact, the Jervois quay sub-station (the main city sub-dtation) is practically completed, and shoulders with Evans Bay the greater part of tramway and lighting power, and this week, stated the Mayor (Mr. R. A. Wright) to-day, the very wonderful installation in Ridel; ford street was tuned up and sent en its way. Householders are most keenly interested in " the cost of the change-over " in the narrower sense, and naturally so, for here the interest is direct—" What will it cost me?"— but the work of licking household installations into shape to carry the new voltage—23o in place of the present 105 —is only one section of the true changeover. The Government station at Khandallah is approaching completion, and to-day cables are running out towards that station from Jervois quay to bring to the city, when the turbines at Manga:>ao start., power in plenty.

FIRST OF ITS KIND IN AUS-

TRALASIA.

The Riddiford street sub-station is unique in Australasia, probably the most up to date south of the Line, a siation which minds its own business, and manages its own business, for here electrical devices of complex design [ lake the place of hands and brains. When the load , calls for power from this wholly automatic station the mechanism responds: when the . demand ceases the station shuts down. It does not think, it operates, for the brain v.ork is all done, the brain work of electricians—British electricians—who plan.r.ed and improved and improved a^ain until was produced a plant which operates or ceases to operate as required at the moment. To detail the mechanism is a task for,an expert electrician only, to understand that detail is a task for a. second expert. The outsider, the man who understands electricity fully, to the extent, say, of replacing a blown-out fuse (which he may have no right to do) or replacing a burnt-out globe (which he has a right to do) may stand inside the door of the sub-station, circumstances permitting, when the plant starts up. The main switch goes home a noisy business, then upon three ofour separated switchboards things begin to happen. No one touches anything, electro-magnets, solenoids, devices of strange design, take the place o, hands. One after the other switches move up to go home, making ready for tne next interlocking step, till the whine o Hie rotary (supplying tramway power, quite distinct from lighting power) ml creases and reaches a higher pitch, a tliousand revolutions per minute. The man who understands the replacing of a lam SCratches his head- It is beyond ' CONTROL SYSTEMS.' There are several ways in which the station can be made to operate: by time —a- clock extraordinary, yet sufficiently unimposing, set to switch in at a certain hour and to switch out at a fixed Hour; by load requirements, the station coming in automatically as the demand for power climbs: or by a pilot line de°nt headqu'^ters> each sJ". stem indepenSAFETY FIRST. Very wonderful are the safeguards and safety devices. If a bearing overheats a tnermostat comes into operation and puts things right; if an accident occurs in a city street and overhead gear comes down, power shuts off for a min|me or so, and then comes on again. | (Moral: Get rid of the overhead gear withm the limit!). If the load varies so may the output, and so on, and so on. lhe thinking was done in England, thfi plant carries the thoughts into practic«. I j SOUND-PROOFED. j Not only does the station carry on solo, it carries on silently, for the walls. | doors,, and windows are double, and beI tween the brick and coke-breeze walls, over the coiling and between the woodj work of_ the doors is a, further insula- | tion against sound waves, a peculiar in- ! sulation indeed, merely a two-inch layer of a fine, thoroughly-dried sea grass which grows on the* American'coasts and has been found to be particularly effective in stopping sound. Inside there is 1 the roaring whine of the rotary machine [ which transforms alternating to direct current; outside there is no sound above! jalow hum, which may be done away | with altogether by the "trapping" of'i air vents and the breaking up of the sound waves, very much as light is trapped in a photographer's darkroom lamp. The. greater noise is caused when the plant starts up, for heavy switches ; rattle home noisily, but as "far as the I passerby may know the machinery is j t dead; no sound will reach him. TRANSMISSION PROBLEMS. As in the Jervois quay sub-station, the duties of the plant are divided between the supply of tramway and lighting power. From Evans Bay and over Constable street comes bulk power at 11,000 volts, alternating current. At the station it is stepped down still as alternating current to lower voltages by means of stationary transformers having no rotating parts, and this power goes out directly to the street reticulation for lighting purposes (to be transformed again to lower voltages in smaller substations) and all is so far straight sailing. As far as efficiency and silence are concerned these stationary transformers might be placed anywhere, for the stepdown transformers are merely street pole transformers upon a larger scale;, but the rotary converter,' which takes in alternating power and gives out direct current for tramway purposes, is a different matter altogether. Here is the noisy chap, the plant which is operated by delicate and complex electrical mechanism in place of hands and brain. When power is carried any distance there are transmission losses. Power at a high voltage transmits with a low loss, low voltage at a high loss, and bulk power is therefore being brought in from Evans Bay and the Khandallah station at 11,000 volts (to Khandallah from Mangahao at 110,000 volts) in order to minimise these losses, and so again is sent out (for lighting purposes) from city sub-stations at « much higher voltage- than may he directly utilised for lighting, to be watered down again to the right consistency by means of smaller stationary transformers. Not so with direct power for tramways. A stationary transformer is expensive; a rotary converter (alternating Ito direct) ig exceedingly expensive, con-

sequently there may not be too many of them, but still remains the problem of overcoming transmission losses. Tramway power cannot be juggled with once it has left the power station, as direct current voltages cannot be raised or lowered in stationary transformers. Consequently the. sources of supply must bre as near as possible to the pouits of application.

In the past. Wellington's trams have all been supplied with power from the old station in Jervois quay, and, as there were very considerable losses in transmitting power at SCO volts (a comparatively low voltage) over such distances as to Seatoun, Lyall Bay, Island Bay, and Newtown it was "necessary to install "boosters." Voltage is electrical pressure; the pressure fell off on long lines, and the "boosters," simply pumped the. pressure up to normal.. To-day that system is practically clone away with. . Tramway power to the east oE Mount Victoria .* is supplied from Evans Bay, the southern districts are supplied from the Newtown rotary,connecter, the city from converters at the Jervois quay sub-station.