GB190627330A - An Improvement in the Application of Protective Devices to Electrical Transforming Machinery - Google Patents

Abstract

27,330. Sayers, W. H. Dec. 1. Distributing; switches; cut-outs.-In a protective device for transforming machinery, an overload' relay is connected in the primary circuit, and when operated causes switches to open the secondary circuit or circuits, and then if necessary to open the primary circuit. The device is shown in Fig. 1 applied to a motor-generator, the coil R of the relay being connected in circuit with the primary member M. The core of the relay operates a switch arm to make contact with pieces F, J successively. When an overload occurs, the core moves the arm N on to the contact F, thereby closing a circuit from the battery E through the coil H. This causes the switch I in the secondary circuit G to open. If this removes the overload, the core of the relay R drops back to its original position, but otherwise it continues its motion whereby the arm N touches the contact J, thus closing the circuit of the coil K. This causes the switch O in the primary circuit to-open. The primary circuit is therefore not opened by any overload that can be removed by opening the secondary circuit. The switch arm may be provided with a roller contact, and may be mechanically connected to the core of the relay or may be connected by other convenient means. A modified form of switch is shown in Fig. 3. Two levers 1, 2, 3, and 4, 2 are pivoted on a common spindle, the levers being bent so that the lever 4, 2 passes across the other as shown. The end 3 is moved upwards by the relay core, and the end 4 drops into the contact 6 to operate the cut-out in the secondary, circuit. The end 1 of the other lever is free to continue its motion to close the circuit of the tripping-coil of the primary cut-out, if necessary. The end 3 is shown in Fig. 3 as lifted by the core 11 of an electro-magnet 7, which is energized by the operation of the relay. A dash-pot 13, vane, or train of wheels may be employed to steady the motion and to create a sufficient interval between the contacts. The device may be used for a number of secondary circuits, or to close a number of circuits in a predetermined order, by increasing the number of levers and contacts.