GB190800468A - Improvements in or relating to Maximum demand Electrical Meters. - Google Patents

Abstract

468. Siemens Bros. Dynamo Works, [Siemens-Schuckertwerke Ges.]. Jan. 8. Current and energy meters. - The non - return pointer of a maximum-demand indicator is driven for predetermined periods from a constant-speed motor, such as a clock or an alternating-current motor, through intermediate gear which is intermittently connected, or through variable gearing, the ratio between the times of engagement and disengagement, or the gear ratio, being controlled by a device actuated by the current or the power, the maximum value of which is to be indicated. In the form shown, a pinion d is in engagement with the last wheel c of the clock-work train, and is mounted so that it may move around this wheel. Mounted on the axis of the pinion d is an eccentric g, which during part of its revolution, comes into contact with a lever k controlled by a solenoid h, and thus causes the pinion d to ride out of gear with the wheel f; when not so raised, the pinion d drives the wheel f and a non-return pointer m, by a pin l. The wheel f is retracted to its zero position by a spring n at definite intervals of time, owing to the release of a pawl p<1> by a pin o on a wheel b of the clock-work train, which may also lift the pinion d out of engagement with the wheel f. A hot wire may replace the lever k and solenoid h, its sagging corresponding to a deflexion of the lever ; or other devices, such as alternating- current coils acting on a short-circuited armature, or, in the case of polyphase currents, two or more current and potential coils acting on an armature, may be employed. When the maximum-demand indicator is used in connexion with a clock meter, the intermediate mechanism may be driven from the clock-work of the meter.