GB946213A - Improvements in or relating to electric power supply arrangements - Google Patents

Abstract

946,213. Automatic voltage control. GENERAL ELECTRIC CO. Ltd. Jan. 25, 1962 [Nov. 2, 1960], No. 37681/60. Heading G3R. A power supply arrangement for providing different stabilized potentials on each of four supply lines 1, 2, 3 and 4 relative to an earth line 5 comprises a known stabilizer circuit 11, 12, 13 or 14 which is associated with each supply line and which includes a series impedance element, e.g. a transistor, 15, 16, 17 or 18 and an error sensing amplifier 19, 20, 21 or 22. The current flowing in lines 1, 2, 3 or 4 is prevented from exceeding a pre-determined value by limiting circuits 25, 26, 27 and 28,which, see circuit 25, each include a transistor 29 connected to its associated impedance element, a low value resistor such as 24 carrying the line current, a Zener diode 33, and a positive potential supply line 35. A variable resistor 31 is adjusted so that transistor 29 is just not conducting when the maximum current is flowing; when this maximum current is exceeded, the voltage drop across resistor 24 increases and transistor 29 begins to conduct whereby the associated series impedance element is biased to reduce the current. The subsequent fall in potential in any affected line 1, 2, 3 and 4 is then used to switch off the whole arrangement, and so prevent possible damage to the equipment being supplied; the circuit for achieving this is described, and includes a transistor 39, a Zener diode 37 connected.to line 1, a resistor 48 connected to line 4, and a transistor 41 connected to each of the impedance elements 15, 16, 17 and 18. The arrangement is such that transistor 39 conducts when the potential between any line and earth decreases whereby transistor 41 is also caused to conduct so that a positive potential is applied to all the impedance elements which results in a rapid switch-off of the lines 1, 2, 3 and 4. Specification 946,212 is referred to.