PL151663B1 - A system for connecting a separated alarm system located in an explosion hazard zone with an alarm control panel located outside the zone - Google Patents

Description

RZECZPOSPOLITA PATENT DESCRIPTION 151 663

POLAND

Additional patent to patent no.- Filed: 86 08 05

Int. Cl. ⁵ G08C 19/02 (P. 260950)

OFFICE

PATENT

RP

Priority - Application announced: 87 03 09

Patent description published: 1991 03 29 cniEimi • G ί LIIS

Creators of the invention: Adam Majchrzak, Andrzej Gemel, Kazimierz Oleszczuk, Zbigniew Górski

Authorized by the patent: United Zespół Gospodarcze Sp. z o. o.

Ship Apparatus Production Plant,

Sopot (Poland)

A system for connecting a separated alarm system located in an explosion hazard zone with an alarm control panel located outside the zone

The subject of the invention is a system for connecting a separate alarm system located in a potentially explosive zone with an alarm control panel located outside this zone.

The separation and signaling system and the intrinsically safe detection line known from the patent description No. 70,536 is included in the circuit of a conventional non-intrinsically safe detection line, also supplied from a conventional alarm control panel. It acts as a separator between the control panel and the detection line, ensuring its intrinsically safe feature. The power supply included in this solution is a DC to AC voltage converter and is in the form of a transistor astable multivibrator. The output of the converter is connected through a capacitor to the primary winding of the transformer, which is an element coupling the converter with the detection line. The step-down transformer has a grounded metal shield between the primary and secondary windings to prevent breakdown. A detection line is connected to the terminals of the transformer secondary winding being the system output. A voltage divider is connected in series with the primary winding of the transformer, consisting of two resistors connected in series. In the emergency state, it limits the current flowing from the primary winding to a value that prevents the ignition of gases or vapors on the secondary side, i.e. in the detection line. The center of the voltage divider is connected through a rectifier system with the input of the transistor amplifier, on the output of which the element transmitting the signaled states to the control panel is switched on. The transformer is the circuit which connects the power supply with the line and the line with the amplifier.

The known and described system, although it fulfills its purpose well, has limited possibilities of application to detection lines containing sensors of passive type, i.e. which do not require power supply for their operation.

151 663

Barrier-type separation systems based on zener diodes are also known and used. These systems operate at grounding the non-separated side, which makes their use in many cases impossible, especially in shipbuilding, where grounding of the systems is not allowed.

Currently, modern detection lines use sensor elements that require the supply voltage necessary for their operation, and are characterized by different values of operating currents. The resulting need to construct a separation system transferring the voltage directly and linearly from the non-separated side to the separated side, preferably the voltage signaling from the control panel supplying the detection line.

The invention solves the problem of designing a new system that meets the current requirements for a detection line consisting of active elements, using the signal voltage from the control panel, feeding the line, especially in the shipbuilding application.

The circuit according to the invention is characterized by the fact that it comprises a bridge switching circuit powered by the signal voltage from the detection line, which converts this voltage into a high-frequency voltage with an amplitude equal to the signal voltage value, at the output of which are connected separating capacitors and a full-wave rectifier.

The solution according to the invention is simple, it is characterized by considerable certainty and reliability of operation.

The subject matter of the invention is described in detail in an embodiment thereof and illustrated in the drawing showing a schematic diagram of the system.

The active element is the bridge switching circuit 1, to the output of which a full-wave rectifier is connected through the capacitors C1 and C2. A detection line is attached to the system

3. The bridge keying circuit 1 is supplied with the signal voltage from the control panel, not shown in the figure. The high-frequency output voltage, after passing through the separating capacitors C1 and C2, is rectified in the full-wave rectifier 2 and constitutes the voltage supplying the detection line 3. Load changes on the separated side are transmitted by the bridge switch 1 in a linear manner and cause changes in the control panel signal voltage. They can be used to signal any state of a detector line 3.

Claims (1)

Patent claim A system for connecting a separated alarm system located in a potentially explosive zone with an alarm control panel located outside this zone, characterized in that it includes a bridge keying system (1) supplied with the signal voltage of the detection line (3) from the alarm control panel, to the output via capacitors separators (Cl, C2), a full-wave rectifier (2) is connected, which is the output of the system. Department of Publishing of the UP RP. Circulation 100 copies Price: PLN 3,000