Alternators
The first demonstration of the Ferranti-Thomson dynamo, the announcement of which had been greeted with much incredulity, was staged by the Hammond Electric Light and Power Supply Company on their premises in an arch under Cannon Street Railway Station. Leading scientists, electricians and representatives of the press witnessed the demonstration and described it as 'one of the most interesting exhibits of electric lighting yet seen'. The machine's chief feature was its remarkable compactness resulting from the unusual form of armature and the small gap in the magnetic field system. The armature was made in `zig-zag' form from a single strip of copper 1/2 in. wide and 120 ft. long. It weighed only 18 lb. and contained no iron. The field system consisted of thirty-two electromagnets disposed around a frame built in two halves with sixteen electromagnets on each half. Excitation of the field magnets was performed by a separate small dynamo driven by the same engine as that used for driving the alternator, while two phosphor-bronze brushes collected the current from the armature.
The alternator measured only 24 in. by 20 in. by 18 in., weighed only I H cwt. and yet was stated to be of a nominal power of 500 incandescent lights. Driven at a speed of 1,920 r.p.m. corresponding to a frequency of 256 cycles per second, the machine was to be seen supplying current to 320 Swan incandescent lamps each of 20 candle power. Larger machines were promised and these soon took shape. A thousand-light dynamo was installed at the First Avenue Hotel, Holborn, in 1883; and two 2,400-volt alternators each to serve 10,000 lamps, were made for the Grosvenor Gallery Station soon after Ferranti became the Engineer there. These latter machines were enormous for the time, each standing 9 ft. 6 in. high with a floor space of 9 ft. by 11 ft, and weighing over 33 tons. They were designed very liberally, one machine running for a long time with a load of 19,600 10 cp. lamps (about 700kW) without suffering injury. The frequency was 83' cycles per second. This appears rather odd until it is remembered that it corresponds to 10,000 reversals per minute, which was the method of stating frequency at that time. No attempt was made to run the alternators in parallel, even for the transfer of load, which was done simply by disconnecting the feeders one by one from the first machine and connecting them to the second.
The first demonstration of the Ferranti-Thomson dynamo, the announcement of which had been greeted with much incredulity, was staged by the Hammond Electric Light and Power Supply Company on their premises in an arch under Cannon Street Railway Station. Leading scientists, electricians and representatives of the press witnessed the demonstration and described it as 'one of the most interesting exhibits of electric lighting yet seen'. The machine's chief feature was its remarkable compactness resulting from the unusual form of armature and the small gap in the magnetic field system. The armature was made in `zig-zag' form from a single strip of copper 1/2 in. wide and 120 ft. long. It weighed only 18 lb. and contained no iron. The field system consisted of thirty-two electromagnets disposed around a frame built in two halves with sixteen electromagnets on each half. Excitation of the field magnets was performed by a separate small dynamo driven by the same engine as that used for driving the alternator, while two phosphor-bronze brushes collected the current from the armature.
The alternator measured only 24 in. by 20 in. by 18 in., weighed only I H cwt. and yet was stated to be of a nominal power of 500 incandescent lights. Driven at a speed of 1,920 r.p.m. corresponding to a frequency of 256 cycles per second, the machine was to be seen supplying current to 320 Swan incandescent lamps each of 20 candle power. Larger machines were promised and these soon took shape. A thousand-light dynamo was installed at the First Avenue Hotel, Holborn, in 1883; and two 2,400-volt alternators each to serve 10,000 lamps, were made for the Grosvenor Gallery Station soon after Ferranti became the Engineer there. These latter machines were enormous for the time, each standing 9 ft. 6 in. high with a floor space of 9 ft. by 11 ft, and weighing over 33 tons. They were designed very liberally, one machine running for a long time with a load of 19,600 10 cp. lamps (about 700kW) without suffering injury. The frequency was 83' cycles per second. This appears rather odd until it is remembered that it corresponds to 10,000 reversals per minute, which was the method of stating frequency at that time. No attempt was made to run the alternators in parallel, even for the transfer of load, which was done simply by disconnecting the feeders one by one from the first machine and connecting them to the second.