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NOTES AND COMMENTS.
*, Large additions are about to be made to the City Council's plant at their Spencer street power station. Chief amongst these will be the installation of a 6,500 k.w. turbo- alternator set, that is being constructed by the British Westinghouse Electric and Manufacturing Co., Manchester. The cur- rent will be three-phase, 6,000 volts, with a periodicity of 50 per second. The turbines will be of the Rateau impulse type, with a normal speed of 1,500 r.p.m. Small steam turbines drive the condenser pumps, a some what novel feature as yet in Australian practice. Small turbines are not very eco- nomical motors, but in a case such as this where they exhaust into a stage of the main
turbine nearly all the loss that occurs is made good. The council are also putting in a 1,500 k.w., three-phase-to-direct-current rotary converter, made by the same com- pany. This machine, which is self-starting and self synchronising, will be operated at 6,600 volts, with a periodicity of 50 on the alternating current, and it will supply direct current at voltage varying between 180 and 530.
The installation of the new turbine set Swill call for more boiler power, and this will be supplied by four single Babcock and Wilcox water-tube boilers, arranged in bat- teries of two. They will be fitted with the usual chain grates, and the ashes will be carried away by a bucket conveyor. A later development in this line is the impulsion system, where the ashes aro ground up and then shot into an overhead bin by means of compressed air. It is employed at the Spotswood power station; but the City Council, owing to the arrangement of the boiler-house, was obliged to adopt the older fashioned method. The boilers, it should be said, have each an evaporative capacity for 17.000lb. of steam an hour, or a little over half that of the Spotswood boilers,
which are of the same make. Probably the marine type adopted at Spotswood would have been preferred at Spencer street also, but owing to the lay-out of the boiler-house the land type had to be instilled. Steam will be generated at 165lb. to the square inch, and it will carry 200deg. of superheat.
.' With the additional condensers the supply 'of cooling water will have to be augmented. »The inlet and outlet tunnels, which pass under Spencer street, and connect with the .Yarra, still have a large margin of unused rapacity, so that to get the additional water it will be necessary only to add to the pump- ing plant. Tins plant consists of two ver- tical spindle centrifugal pumps, coupled direct to steam turbines. These Were built riy Kelly and Lewis, Bourke street. The capacity of each pump is SOO.OOOgul. per hour against a head of 40ft.
i It is expected that the additions enumer- ated will be completed in the latter part of 'the year.
?; . CORDITE PRESSES.
Four cordite presses, the first of the kind that have been manufactured outside Great
Britain, are now approaching completion al the shops of Kelly and Lewie, Bourke street. These work on the screw principle, and the raw cordite, placed in a small cylin der, is forced through a number of holes in the bottom cover, and it is then wound on reeling-machines, which are also beirig manufactured by the firm. A peculiar fea- ture ia a sort of hydraulic safety valve, which is provided to guard ¡igninst. excessive pres- sures. Should these arise, the hydraulic mechanism throws the belt off the driving pulley.
' v STATE GAS ENGINES.
\ Six' 28-B.H.P. gas engines, with the pro- ducers, are being manufactured at the Bhops of Robison Bros..South Melbourno,for work- ing tho crushing plants that the State has elected at various mining districts in Vic- toria; The pioducers will consume wood in place of coko or charcoal, A thoroughly satisfactory .producer of this kind might be described ns a long-felt want. Where the work is not too intermittent, tome of thora liave given fairly satisfactory results, but in many instances much, trouble has been experienced through tarring. Tho perform- ance of these producers will be watched with a considerable amount of interest, -for ¡t need not be said that if wood can be used
without the prcliminai} procès« of charing there « ill be a saving (.fleeted
Irom time to time correspondent» h-nc asked whethci it is not possible to n sharpen filef and from inquiries mnde amongst the trade I ha\c nliv-iys -inswcred that tins could not be done nt a cost tint would make it woith -while KecentU how c\er n process of io hirpening fi'ei bj means of a wet «and 1)1 ist 1 is been tcstt !
«Inch it is Bald lime Riven verv good results, nnd at a price ti at \ ill tn iblc it to be profilublj eutplo. ed The diptmtuh consists of 1 sheet iron chamber pro» ide 1 with an uptake slurry mixing tank air igitatmg pipe and a slurri pi »jcclor jvorlcd with a stenm jet ihc files are shnrpeucd bj being hel i in Ruth a m inner tint the backB of the teeth arc exposed to the. cutting action of the. sand It is stilted that sharpening bj lins method is by no means a merol\ mechanical operation
but that it is one which calls for i con sidcrablo degree of si ill
ANSWERS TO CORRESPONDENTS
Redgum -This correspondent would like to get some particulars of i ortablo ma clunes for boring holes in tnubei These might be either hand dii\en or power migl t be used m the form of compressed air or of electric eurretit If imv render u onld kindly supply the information I ii onld for
T J (Hawthorn) -M rite to ti e secre- tary A letomn Institute of . nginecrs Hie volume that \ou refer to is not obtainable at bool sellers sho] s
IKW (Glenrowan)-"Sou ein eilen late the poner of your engine ivtth s iflieient accuracy bj this rule -Multi, ly the mimi cr of impulses per minttt bj ti c pistou dis placement, and du ide the res tit bj i 4 J his will gue the brake horse-powoi Ii otc that there is only one impulse in cicrj four strol es The question is not clear and to save any chance of error I will send jon a sketch of the thcrmo svpl on tystcm of cooling
limier (Bright) -There would be no diflicultj about driving a sin ill circular saw ora lathe and w ith a fan there would be no danger of over healing assuming of course that the fan is large enough for the purpose
lins use of a motor bicycle engine, is com | mon enough on American farms j