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Title: |
1896 Article-Emerson Electric Co., A. C. Electric Motor |
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Source: |
Western Electrician, 11 Jan 1896 page 22 |
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Insert Date: |
10/24/2011 1:08:37 PM |
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The Emerson Electric Manufacturing company, St. Louis, Mo., a pioneer in the manufacture of alternating current fan motors, is now introducing to the trade a line of small alternating current power motors, the ½ horse power size of which is herewith illustrated. These motors are non-synchronous, though practically constant speed, the speed regulation being within five per cent, between "no load" and the rated capacity of the motor. They are said to possess nearly all the features of excellence of a direct current motor, while being superior in that they having no commutator in circuit (except while starting) and call for no attendance at the brushes. They are absolutely protected from lightning, from being placed on the secondary side of the current, and, being arranged for low voltages, they are protected from the burn-outs due to high potentials and broken wires, which are especially troublesome in 500 volt current motors of small size. No starting box or other device is required in starting the motor, the stopping and starting being effected by a single lever. This lever moves across a sector as shown in the engraving, with three notches marked respectively "Off," "Start" and "On." The lever is allowed to remain in "Start" notch until the motor has attained its normal speed, when it is pushed to "On." In moving to this latter position the brushes are lifted off the commutator, the external current thus having no connection with the armature winding in this position. The switch and fuse terminals are mounted on the motor itself, the only wiring required with these motors being the introduction of the circuit leads into the terminals. The stock sizes of these motors are made by the Emerson company for 16,000 and 7,200 alternations per minute and for 104 volts. Other voltages and frequencies are made to order. The following are some of the features of merit claimed by the makers for them, the tests having been obtained with ½ horse power motors, and still better results being assured for larger sizes: A starting torque5o per cent in excess of the running torque; a maximum output of 50 per cent in excess of the rated capacity of the motor; a consumption of energy, running free, of less than 25 per cent of that under full load; an efficiency of from 65 percent cent to 80 percent, according to size and frequency; speed regulation within 5 per cent; a very slight diminution of torque until the speed the special disadvantages of synchronizing motors); a power factor at full load, of 67 percent on the 130 cycle circuit and 80 per cent on a 60 cycle circuit for a horse power machine. These motors are practically noiseless except while starting. They are provided with self-oiling, self aligning phosphor-bronze journals and a cast steel shaft, the oil boxes being arranged with gauges and cocks, no expense having been spared to make these parts of the motor of the most approved mechanical construction, as indeed they have to be, since the clearance of the armature is a little more than 1-100 of an inch. The Emerson Electric Manufacturing company is putting these machines out under its usual guarantee and is finding a ready demand. It has in preparation sizes from ¼ to 3 horsepower and is prepared to make prompt shipment on the ½ and 1 horse power machines of any frequency. Other sizes and a fuller line are promised at an early date. |
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1896 Emerson Electric Co., A. C. Electric Motor
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