Patent GB-418782-A (GB)
Title: Improvements in apparatus for controlling the consumption of electrical energy by load devices operating on electrical power systems
IPC: H02J3/14
Filed: 1933-09-18
Abstract: 418,782. Lighting and heating systems. ROSS, T. W., 10, Broadoaks Road, WOOLNOUGH, G. L., 32, Northenden Road, both in Sale, Cheshire, and ASSOCIATED ELECTRICAL INDUSTRIES, Ltd., Crown House, Aldwych, London. Sept. 18, 1933, No. 25801. [Class 38 (iv).] An electrical control apparatus for limiting the total consumption of electricity during an integrating period is operated only during the latter part of the period to reduce the load progressively in accordance with the excent of the increase in the rate of consumption above the predetermined value during the earlier part of the period. One element 17 of a differential gear is driven by gearing from a watt hour meter 3 and another element 28 is driven by gearing from a constant speed element such as the armature 36 of a synchronous motor, the gear ratios being such that the two differential elements 17, 28 are driven at equal speeds in opposite directions when the average rate of current consumption is equal to the predetermined maximum value. If this average rate is exceeded during the earlier part of the measuring period, the planet members 16 rotate and thereby rotate the control drum 2 from its zero or starting position in which a pin 86 engages a stop 87. A spring 84 tends to return the drum to this position. The conducting portion 5 of the drum 2 is always in contact with the contact 7 and engages the contacts 8-11 in succession in accordance with excess current consumption during the early part of the period, whereby current consuming units such as motors may be cut out through the medium of their operating coils 90, 91, 92, 93 which are supplied with current as required from the means 44, 45. This control cannot, however, be exercised until a definite part of the integrating period has expired as determined by rotation of the drum 38 by the constant speed element 36 from a zero or stop position to which a spring 88 tends to return it. At the end of this first part of the period that is, when the drum 38 has rotated through a certain angle, the conducting portion 40 engages contacts 41, 42 thus rendering the motor relay circuits available for operation if required. Should the conducting part 5 of the drum 2 then be engaging one or more of the contacts 8-11, the corresponding number f motors will be cut out. The solenoid 47 is energized at the same time so as to move its armature 49 and a spring controlled lever 50 upwards, whereby gears 54, 55 are engaged and a slidable member 57 is slowly moved downwards during the second part of the period. The member 57 carries contacts 58-61 which engage fixed contacts 66-69 respectively when in the upper position, these latter contacts being connected to the drum contacts 8-11. Towards the end of the downward movement of the member 57, the movable contacts 58-61 all engage the lowermost fixed contact 66 so that all the motors are then cut out, even though only the first contact 8 is engaged by the conducting part 5 of the drum 2. In this way the correcting effect is increased towards the end of the period. A time switch 73 is closed for a short interval at the end of each period so as to energize solenoids 71, 72, thus raising the armatures 74, 75 and operating bellcrank levers 76, 77 which disconnect the gears 21, 35 in the trains of gearing from the meter 3 and constant speed element 36 to the differential gear. This allows the return of the drums 2, 38 to zero and the movement of the member 57 to its raised starting position by the spring 70. The switch 73 also energizes starting relays 96-99 for any motors which have been stopped, but this automatic restarting may be prevented by switches 101.