Intrinsically safe power supply apparatus
First Claim
1. Intrinsically safe portable power supply apparatus comprising a battery source, output terminals connected to the source, a zener diode connected across the source and the output terminals, a current limiting resistor means connected to the source and to the zener diode, in which the battery source is divided into a plurality of sections and including an equal plurality of unidirectional conducting elements, a separate one of said elements being connected across each section of the battery source, the current limiting resistor means comprising a current limiting resistor connected between an end section of the battery source and a unidirectional conducting element, whereby the apparatus is rendered intrinsically safe, whereby upon a break at a first section of the battery, current from a remaining section flows around the first section through a unidirectional conducting element connected across the first section, avoiding high energy level sparking at the break, and whereby upon a break in an end section of the battery adjacent the current limiting resistor, that end section and the current limiting resistor are bypassed by the unidirectional element.
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Abstract
A battery powered circuit has the battery source divided into serially connected sections and each section is shunted by a diode. The breakdown of one section gives only a low powered spark under fault conditions. The circuit can be used in hazardous environments such as coal mines or petrol installations.
32 Citations
7 Claims
- 1. Intrinsically safe portable power supply apparatus comprising a battery source, output terminals connected to the source, a zener diode connected across the source and the output terminals, a current limiting resistor means connected to the source and to the zener diode, in which the battery source is divided into a plurality of sections and including an equal plurality of unidirectional conducting elements, a separate one of said elements being connected across each section of the battery source, the current limiting resistor means comprising a current limiting resistor connected between an end section of the battery source and a unidirectional conducting element, whereby the apparatus is rendered intrinsically safe, whereby upon a break at a first section of the battery, current from a remaining section flows around the first section through a unidirectional conducting element connected across the first section, avoiding high energy level sparking at the break, and whereby upon a break in an end section of the battery adjacent the current limiting resistor, that end section and the current limiting resistor are bypassed by the unidirectional element.
Specification