Charbonnages De France

Cdf Chimie S.a.

Gerard Rose

Maurice Boutonnat

Christian Marget

A power circuit comprises a current amplifier circuit connected between a minimum potential line and a maximum potential line. It further comprises, connected between these lines together with the aforementioned main circuit, a protection circuit which has a control input. A trigger and distributor circuit is connected in parallel with these circuits and is adapted to neutralize the protection circuit, via its control input, when the voltage across the main circuit is below a threshold value. Is it also adapted to activate the protection circuit when the voltage across the main circuit reaches this threshold value, while maintaining the voltage across the main circuit at an approximately constant ratio to the voltage between the two potential lines. The circuit is applicable in particular to controling failsafe alarm circuits, by means of logic signals, for example.

Power circuit and trigger device comprising same

A process of remote transmission of signals issued by at least one sensor over a transmission line, wherein the power necessary to supply the sensor is transmitted by that line in the form of an alternating current signal of approximately constant intensity, and wherein the line fulfills the triple function of supplying power to that sensor, of transmitting interrogation signals from a central station to that sensor and of transmitting data signals in response to that interrogation signal from the sensor to the central station. A device for incorporating this process is also disclosed.

Process and device for the remote transmission of signals and

A two stage process for interrogating a detector of the concentration of combustible gas in an atmosphere. In a first stage, the detector is supplied with a low voltage and the supply is cut and an optional alarm is sounded if a positive signal has been detected. In a second stage, if the signal detected in the first stage is negative or zero, then the detector is supplied with a second, higher voltage. The signal is compared to a predetermined range and, if not within that range, an optional alarm is sounded. A device to apply the process comprising a detector, an amplifier of the signal issued by the detector, a voltage reducing circuit, and a switch that controls the voltage reducing circuit slaved by a discriminator to the sign and/or to the maximum amplitude of the signal output by the amplifier. Application of the process and device to the detection of the concentration of methane.

Process for interrogation of a detector of the concentration of

A measuring cell having a measuring filament and a reference filament is disposed in a cap of sintered metal. A time base circuit, actuated by the closing of a switch, connects the filaments to an electrical supply circuit after a predetermined delay. Subsequently, the time base circuit sequentially triggers the connection of the filaments to a measuring circuit, the storage in a memory of the value of the output signal of the measuring circuit and the display of this stored value, the disconnection of the supply circuit, and the illumination of an end of operation warning lamp. The value displayed is proportional to the amount of a constituent of an atmosphere diffused into the measuring cell. The apparatus can be used as a portable fire damp meter or explosimeter.

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Villers Saint Paul, France

Gerard Rose