FR2599850A1 - Detector of electric arcs - Google Patents

Abstract

The device is an electronic detector of electric arcs, including piezoelectric arcs. The invention relates to a device for detecting electric arcs and the interference caused by them. It consists of a casing fitted with an antenna connected to an electronic deck which shapes the detected signal and stores it in memory in order to trigger a time delay, the signal firstly actuating a relay so as to produce any desired command and secondly starting up a modulated sound amplifier which warns of the detection through a loudspeaker. The device is intended especially for detecting electric arcs or the interference due to them which upsets sensitive electronic equipment or which endangers the immediate environment.

Description

 the present invention relates to a device which detects electric arcs including those of piezoelectric origin which disturb sensitive electronic devices, or which pose a danger to the surrounding environment.

 the main installations generating such effects are generally: devices with switching contacts, motors with collectors, cabling using high voltage.

 The parasites from such installations are propagated in several ways: by coupling (inductive, capacitive, counter-reactive, etc.), by direct connection to the common supply, or by radiation.

 The main devices used to eliminate nerturations of this type are: attenuating filter, isolation transformer, decoupling capacitor, earthing, etc.

 If, despite these measures, an electric arc appears, it is impossible to detect its presence or its origin.

 In a second case, if the electric arc arises in a high-risk environment, without being detected it can have disastrous consequences (gas plant, petroleum complex, deposition of explosives ...).

 the invention therefore constitutes protection yes overcomes these various problems by detecting the presence or the origin of the electric arc.

The detector in question operates as follows:
When the antenna (28) receives a signal, this is sent through the isolation capacitor (I) on the divider bridge constituted by the resistors (3) and (2), a last clipping is made by the diode (4).

 The integrated circuit (7) receiving the tripping information by the midpoint of the bridge, switches for a certain period of voltage set by the resistor (5) and the capacitor (6).

 At this time, it activates the relay (IO) thanks to the transistor (9) which is activated through the resistor (8). The diode (21) is only there for the extra currents of the relay, thus protecting the transistor (9).

 At the same time by the resistors (I5) and (38), the integrated circuit (I2) is triggered which generates a square signal, of shape and duration fixed by the resistors (13) (I4) and the capacitor (21) .

 The square signal thus obtained, passing through the resistor (I6), is injected into the integrated circuit (31) wired in double fixed oscillator.

 The latter composes the modulated sound of siren thanks to the resistors (I7), (I8) and the capacitor (I9), for a first part of the sound, and to the resistors (34) and (35) as well as the capacitor (36) ' for the second part.

 The first sound coming from the integrated circuit (31), crosses the resistor (25) and the capacitor (26) .. The second crosses the resistor (27). The two sounds thus obtained are mixed and sent to the final stage constituted by the transistors (22) and (23) in order to amplify it to attack a speaker of approximately 10 watts and 8 ohms.

 When the integrated circuit (7) reaches the end of its time delay set by the resistor (5) and the capacitor (6), the whole system is reset, prgt for a new detection.

 For reliability reasons, the capacitors (32) and (33) are respectively decoupled there on the supply of the integrated circuits (I2) and (7).

 The capacitors (20) and (37) are used to suppress unused inputs of the integrated circuit (31).

 The contact (II) is the contact activated by the relay (po). Its use is left to the user.

 The contact (30) is a normally closed contact which is connected between earth and the auxiliary input. When it closes, it starts the whole process, just like antenna detection.

 It should be noted that the voltage of the supply designated V + can be between +5 and I5 continuous.

Claims (4)

 DREAM; NDI CATIONS  I) Device for detecting electric arcs characterized in that it comprises an antenna (28) for the. detection, a loudspeaker (24) for signaling. and a servo relay (IO): the device in question stops and resumes detection Sutom tiouement.  2) Device according to claim 7 which warns of detection thanks to a built-in speaker (24), having a modulated sound coming from the integrated circuit (31) and amplified by the transistors (22) and (23).  3) Device according to claim 1 characterized in that a closing contact (30) connected to the zero volt of its power supply and the auxiliary input triggers the alarm cycle at each pulse.  4) Device according to claims I and 3 caract-c- -risé in that it can be powered either between +5 volts and + I5 volts.