New products

New Type Rotor Construction. — Offering the advantage of longer motor life with less maintenance, a new type rotor construction announced by the General Electric Company makes possible the use of cast-aluminum rotors in the larger sizes of double-squirrel-cage motors for high-starting-torque, low-starting-current service. Called the “Valv-amp” rotor, it employs a unique shape of rotor slot and a special method of assemblying rotor punchings to control the flow of starting current. As a result, without the use of a switch or other moving parts, current is permitted to flow in the outer squirrel-cage when the motor is started, thus producing high-starting torque. Then, when the motor comes up to speed, current is allowed to flow through the entire rotor “winding,” resulting in excellent running characteristics. Above is an oblique end view, showing one arrangement of bars, end rings and fans.