DO IT ELECTRICALLY

Dominion, Volume 21, Issue 10, 6 October 1927, Page 13

DO IT ELECTRICALLY

“Accumulator” Plant. The construction of large hydraulic “accumulator” works was recently commenced at Niederwartha, near Dresden, Germany (says an exchange). Water from'the River Elbe is to be raised 500 ft. to an accumulator tank by a generator operated as a motor under “off peak” load energy in order to be available for conversion to peak-load current nt any time dunne the day. Hour units are being installed to begin with, and these will be able not only to cover the heaviest peak loads of the city of Dresden but also, in the event of a breakdown, to take charge of the whole of the normal current supply. The turbine rating is about 30,000 h.p. a unit, and that of each of the pumps is about 27,000 h.p. Each of the four turbines is able to deal with 18.2 cubic metres of water a second against a head of 112 in. Other important accumulator plants of the same kind which have recently been put into operation are the Schwarzenbach works, with a total pump capacity of about 20,000 h.p. and an accumulator head of upward of 400 metres, and the accumulator plant of Tremorgio, by which tile water of the River Ticino is raised by pumps whose aggregate power is 15.000 h.p. to the lake of the same name, at a height of 900 metres. Electrification of Christchurch-Lyttelton Railway. The English Electric Co. have secured an important contract for the complete electrification of the line from Christchurch to Lyttelton, which includes the Lyttelton tunnel, through which the whole of the traffic from the North to the South Island, and vice versa, must pass (remarks an exchange). The order comprises the overhead line equipment amounting to 45,000 yards of overhead line material, six 1500-volt locomotives of the 4-axle type, 3ft. 6in. gauge, each equipped with four D.K. 86 motors and standard camshaft control. _ The electrical gear will be mounted in compartments and protected by doors interlocked with the control. The weight of the locomotives in full working order will be 50 tons, there being two drivers’ compartments, one at each end. Also the necessary sub-station plant, which includes a single sub-station arranged to feed directly on to the middle of the overhead line without any feeders is to be supplied. Two rotaries will be supplied, these being completely automatic in operation, and of the single commutator 1500-volt type. The substations which the company are supplying will be the sole source of supply for the locomotives. Remote control is arranged from both Addington and Christchurch stations, starting being effected by the operation of a single push button in either of these remote points. Ou receipt of this impulse the first machine will start up, automatically synchronise and take load, the. second machine coming into operation either by a second operation of the same push button switch, or, alternatively, by overload and consequent overheating on the running machine. Both machines are designed to take the whole of the loan which is at present expected, so that at present the second machine may be regarded as a. standby to the first. Arrangements will, however, be made by the operation of a single change-over switch, to reverse the sequence of starting so that even operation is obtained between the two machines. Tn addition to the above remote starting arrangement, indication will be given at both remote points that the machines are running or not. and also alarm will be given at Addington Station in the event of either machine being shut down due to a short circuit, or any other reason. The transformers for supplying these converters will be of the standard outdoor type. They will be suitable for taking a supply at 10,500 volts,' 3phase, 50-cycles, and will convert this to the appropriate pressure for the rotary converters. The automatic switchgear will be of standard design. Protection on the d.c. side is by means of a high speed l circuit breaker in the positive main, provision being made for isolation of both the positive and negative connections.