GB1512407A - Apparatus for monitoring the consumption of electricity - Google Patents

Abstract

1512407 Measuring energy and power FERRANTI Ltd 4 June 1976 [6 June 1975] 24475/75 Heading G1U An electricity consumption monitoring system of the type in which feed pulses, each corresponding to the consumption of a fixed quantity of energy are produced, includes means, Fig. 1, for pre-setting the quantity of energy represented by each feed pulse, means for measuring the time interval between each feed pulse, and means for dividing the feed pulse value by the feed pulse period to indicate the actual load (in watts). The arrangement forms part of a monitoring system particularly for use when the supply tariff permits only a certain maximum amount of energy to be taken during pre-set periods of, for example, 30 minutes. To this end the system also includes a counter which is initially pre-set at the beginning of each period to the maximum amount of energy available and which is then counted down so that it always indicates the amount of energy available in the remainder of the period, a counter which indicates the time remaining in the period, and a second divider which indicates the target load which is the maximum average load (in watts) that can be applied until the end of the period without exceeding the maximum energy consumption for the period. The system also includes a subtractor to indicate how much load has to be shed to stay within the prescribed limit. The Specification describes a block diagram Fig. 4 (not shown) using conventional digital techniques for implementing the system. The maximum demand, and the feed pulse value, are set on decade switches, and the period of the feed pulses is measured by counting clockpulses. Division is effected by counting both the numerator and denominator registers to zero, and re-entering the denominator each time its register reaches zero. One divider is time shared to effect the ten divisions that are required. Various visual and audible alarms may be included if the actual load exceeds the target load by too much.