Patent ID: 6111738
Filing Date: 2000-08-29
Classification: H02H

Abstract:
An intrinsically safe circuit for use in a hazardous environment, the circuit comprising: a plurality of circuit sectors located in the hazardous environment and which are substantially isolated physically from one another by electrical insulating means, the circuit sectors being electrically connected, directly or indirectly, so as to define at least one power transfer path between each said circuit sector and at least one other said circuit sector; power supply means located in the hazardous environment and connected to at least one said circuit sector; and power limiting means provided between said power supply means and each said circuit sector connected thereto, wherein at least two said circuit sectors having at least one power transfer path defined therebetween have different sparking voltages and the intrinsically safe circuit further includes voltage clamping means in each said power transfer path between at least two said circuit sectors having different sparking voltages, for reducing the maximum voltage which may be applied by one of said at least two circuit sectors to another of said at least two circuit sectors.