Document nmaBDNNvyVMkqEK2eyz8zvBVm

Motors and Controllers GENERAL ELECTRIC COMPANY SCHENECTADY, N. Y. Sales Offices in Principal Cities Motor and Control For Heating, Ventilating and Air Conditioning Systems Quiet Operating Motors The Need for Quiet Operating Motors This company has, for some time, been aware of the fact that induction motors of the general purpose line are not quiet enough for.use in office buildings, schools, etc., where quiet operation is of great im portance, although these motors are not objectionable for other classes of service. This fact was pointed out at various times so as to guard against the application of standard motors in such locations, but this warning has been generally disregarded, and although a great number of standard motors have been applied successfully in such buildings, there have also been a number of complaints on noise from customers who have used standard motors. Acoustics of the Structure, Location and Mounting The problem of reducing noise in build ings should not be left entirely to the motor manufacturer, and although it has been found that many architects fully appreciate the noise problem and their specifications cover very fully the pre cautions which must be taken in mounting the equipment, there are architects who are apparently overlooking this problem entirely and make no provision for cover ing this point at all. Concrete, which is usually used in con junction with steel in modern building con struction, is a nearly homogeneous sub stance of high density, liberal elasticity and is an excellent conductor of sound waves, while concrete arches are potential sound amplifiers. The importance of correctly designing foundations is best illustrated by a case which has come to our attention where, in the motor-room, there was no objectionable noise, yet on certain lower. floors,, the noise was very objectionable, the noise being transmitted by the steel work and amplified by the sounding-board effect of the walls, and sometimes further intensified by localized resonance. MTB Wound Rotar Quiet Operating Induction Motor One of the best methods for preventing the transmission of sound is to use a laminated structure across the direction of the sound wave, the lamination varying in density so as to cause multiple reflection. Materials which can be used in con structing proper foundations are cork pads (2 to 3 in. thick), felt pads, sheet lead, wood and sand used in combination with reinforced concrete or steel. It has been found that when cork is used, the foundation- should be designed so that the pressure on the cork will be 30 lb. per sq. in.; either more or less does not seem to produce as satisfactory results. A block of cork 2 in. thick should not com press more than 0.272 in. under'a pressure of 10,000 lb. per sq. ft. of surface area. The installation should be made so as.to eliminate any metal-to-metal contact between motor and building. The use of short center belt, texrope drive or worm gear drive should be recom mended wherever possible as this enables. higher speed motors to be used--900 and 1200 r. p. m. motors are recommended rather than the lower speed motors such as 450 r. p. m., giving better efficiency and far better power factor. In addition, the connecting of motors in this way allows proper insulating foundations to be used under the motor without affecting the line-up of the drive. Where the motor is direct connected to the drive, especially low-speed fans, the most satisfactory This Company will gladly assist in the solution of any electrical problem in relation to heating and ventilation 746 General Electric Company Motors and Controllers Motors and Control For Heating, Ventilating and Air Conditioning Systems Alternating Current Control rounding structure is a very important point, and while in one location a perfectly standard motor may be acceptable, the same motor may be entirely unsuitable in another location. CR77G5.1-6 Hp. Controller method of mounting is to have both motor and fan on a common base, the whole base being mounted on proper insulating sup ports. Where the fan and motor are not on the same base, it is difficult to use any sound absorbing insulation under the motor without causing difficulty in keeping the equipment properly lined up. The location of the motor in the building with reference to the acoustics of the sur Switches CR776I-F1, 0-60 Hp. Controller Method of Operation Type Manual Manual Push Button Push Button CR1924 CRI036 CR7006 CR7006FI Horsepower Range Overload Protection Remarks '/.-so '/,-S 1 -50 1 -5 Fuse.............................................. thermal Cut-outs. Temperature Relay................ Fuse and Temperature Relay Safety Type. Contactor. Combined Magnetic Switch and Disconnection. Manual Manual Push Button Push Button Push Button CR10M CRI042 CR7056 CR705I CR7773 5 -50 5 -15 2-50 5 -50 1 -5 Starters Temperature Relay................ Temperature Relay................ Temperature Relay................ Temperature Relay................ Time Limit................................ Compensator Type. Resistance Type. Resistance Type. Compensator Type. Combined Magnetic Starter and Circuit Breaker. Manual Manual Manual Push Button Push Button CRI264 CR7764CI CR7764Y1 CR7765 CR7761 1 -15 71/2-50 5 -50 1 -5 5 -50 Speed Regulators Temperature Relay................ Time Limit................................ Temperature Relay................ Temperature Relay................ Requires Separate Switch. Combined Regulator and Switch. Combined Regulator and Circuit Breaker. Preset Speed Type. Remote Speed Indicating. The General Electric Co. manufactures a complete line of control devices for starting and controlling motors driving ventilating fans. The table above gives briefly the line of controllers for use with alternating current motors. All control lers are of the enclosed type externally operated. Speed regulators are designed This''Company will gladly electrical problem in relati to give 50 per cent speed reduction on fan load and arranged to maintain equalized current in all phases of the rotor which is necessary to maintain quiet operating motors. Details may be obtained at the nearest sales office. sist in the solution of any to heating and ventilation