GB454755A - Improvements in and relating to protective relays - Google Patents

Abstract

454,755. Measuring current. AKT.- GES. BROWN, BOVERI, & CIE, Baden, Switzerland. Feb. 4, 1936, No. 3324. Convention date, Feb. 4, 1935. [Class 37] [See also Group XXXVII] A protective relay in which the force exerted on the movable relay member varies continuously with its excit. ing current and is utilized during operation to indicate visibly the momentary value of the factor to be kept under observation by, for example, a pointer moving over a scale is arranged to have the movable relay member coupled below the limit of response of the relay with the indicating appliance and above this limit with the releasing device of the relay. As shown in the Figure, the operating member consists of a Ferraris drum rotor c in the air gap of a core a with winding b and shading rings e on the pole faces. The drum is mounted on a shaft d which has a pointed lower end supported in a conical fixed bearing g and a movable intermediate bearing h. Normally, a pinion i on the shaft d engages a pinion o on a shaft n carrying a pointer p moving over a scale r, the shaft n being rotatable against a spiral spring q. Thus, with normal loading of the controlled circuit an indication of the value of the load value is given, but when abnormal conditions occur an electromagnet z attracts its armature v moving the bearing h to the right against the spring f and so disengaging the pinion i from the pinion o and moving it into engagement with the pinion t. The shaft s on which the pinion t is secured is then rotated causing the closing of contacts, the tripping of a circuit-breaker or any other relay action.