JP3030393B2 - Collective safety cage - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to security retainers, and more particularly to collective security with reduced cost and space per channel.

[0002]

2. Description of the Related Art As shown in FIG. 2, signal lines L ₁ , L ₂ ,
..., L _n a (hereinafter referred to as hazardous area) risk in an explosive, such as petroleum storage tanks have been, for example, a plurality of installed 2 level sensor 3 electrical circuit or signal lines M ₁ derived from elements such as , M ₂ ,..., M _n , respectively, the safety cages 4 ₁ , 4 ₂ ,.
The 4 _n installed, the signal lines L _i and M _{i (i} = 1~n) and a safety cage 4 _{i (i} = 1~n) via a connecting signal lines of the hazardous area M ₁ ~M _n The current / voltage flowing through the power supply is limited to ensure safety.

The safety retainer 4 is about the size of a case containing 20 cigarettes, has an appearance as shown in FIG. 3A, and has a general circuit connection terminal T, an intrinsically safe grounding terminal G and a safety holding terminal A coaxial intrinsically safe circuit connector CN for connecting the device to a signal line in a hazardous area is attached. As shown in FIG. 3B, a,
A safety explosion-proof circuit N having three terminals b and c is accommodated. The circuit N includes, for example, a resistor R and a fuse F connected in series between input / output terminals a and b, and four Zeners connected in series between a connection point of the R and F and a ground terminal c. composed of the diode D _Z.

The terminals a, b, and c are connected to a connector CN, a terminal T, and an intrinsically safe ground terminal G mounted on the case 5, respectively.

[0005]

The conventional safety retainer has the following features.
Since one signal line is required per channel, that is, one signal line (L _i , M _i ) to be connected to each other, if the number of channels is large, a large space is required and the equipment cost is also large. There was a problem. It is an object of the present invention to significantly reduce the equipment cost and occupied space per channel of a safety retainer.

[0006]

According to the present invention, a case,
M (m is an integer of 2 or more) wiring boards held in the case and stacked in multiple stages, and n (an integer of 4 or more) channels of safety mounted on each of the m wiring boards An explosion-proof circuit, n coaxial intrinsically safe circuit connection connectors mounted on each of the m wiring boards, and connecting one input / output terminal of each safety explosion-proof circuit to a signal line in a hazardous area; Mounted on each of the wiring boards
A multi-terminal general circuit connector housing n terminals for connecting the other input / output terminal of each safety explosion-proof circuit to a signal line of the general circuit, and n terminals provided on each of m wiring boards Collective safety terminal consisting of a common ground terminal that collectively connects the ground terminals of the safety explosion-proof circuit to the outside and an intrinsically safe ground terminal that is attached to the case and connects the common ground terminal to an external common potential point This is to propose a retainer.

According to the structure of the present invention, n or more safety explosion-proof circuits are mounted on a single wiring board, and naturally, m wiring boards are stacked and arranged in a case. Since a multi-terminal connector in which n terminals are collectively accommodated for each wiring board is used, there is an advantage that the volume occupied per channel can be reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the embodiment shown in FIG. In FIG. 1, parts corresponding to those in FIG. 3 are denoted by the same reference numerals. For example, the wiring boards 6 and 6 ′ are held in a metal case 5 in a two-stage (generally multi-stage) manner. Each wiring board 6 (6 ') has a safety explosion-proof circuit for n (an integer of 2 or more) channels (for example, three input / output terminals a and b and a ground terminal c as shown in FIG. 3B).
And consisting of terminal _{circuits) N 1 ~N n (N 1} '~N n'),
n coaxial intrinsically safe circuit connectors CN _{1 to} CN
_n (CN ₁ ′ to CN _n ′) and a multi-terminal general circuit connector T (T ′) containing n terminals for connecting the safety explosion-proof circuits to signal lines of the general circuit are mounted. .
The ends of the connectors CN _i , CN _i ′ and T, T ′ connected to the mating connectors are similar to the connector CN of FIG. 3A.
It protrudes outside through a hole formed on one surface of the case 5.

The n safety explosion-proof circuits N _{1 to} N _n (N ₁ 'to
N _n ') the common ground terminal g to be connected to an external collectively each ground terminal c of (g') is provided in the vicinity of the edge of the wiring substrate 6 (6 '). A common intrinsically safe ground terminal G connecting these common ground terminals g (g ') to an external common potential point.
(G ′) is attached to the case 5. Wiring board 6
(6 ') ground terminal g (g') and ground terminal 2G (G ')
Are connected by lead wires 7 (7 '), respectively.

In the present invention, as described above, a plurality of safety explosion-proof circuits are collectively mounted in one case in order to reduce the size and cost of the safety retainer per channel, but in order to further reduce the size. The safety explosion-proof circuit mounted on the wiring board is coated with an insulating material such as polyurethane, and the distance between the wirings is considerably smaller than when not coated (for example, the distance of 3 mm is reduced to about 1 mm),
The dimensions of the wiring boards 6, 6 'are made as small as possible by high-density mounting.

[0011]

As described above, while the independent safety retainer is conventionally mounted for each channel, in the present invention, a wiring board in which a safety explosion-proof circuit for n channels is mounted in one case. Since one or a plurality of sheets are accommodated in a stack, the equipment cost and the occupied space per channel of the safety retainer can be significantly reduced as compared with the related art.

When the safety explosion-proof circuit mounted on the wiring board is coated with an insulating material, the size can be further reduced.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of the present invention, wherein A is a perspective view, and B is
Is a basic block diagram.

FIG. 2 is a block diagram showing an example of a liquid level measurement system equipped with a safety retainer.

FIG. 3 is a view showing a conventional safety retainer, wherein A is a perspective view, and B is
Is a circuit diagram.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02H 9/00 H05K 7/00

Claims (1)

(57) [Claims] 1. A case, m (m is an integer of 2 or more) wiring boards held in the case and stacked in multiple stages, and n (4) mounted on each of the m wiring boards. and an integer greater than one) of channels safe explosion爆回path, wherein is mounted on the m respective wiring board, n-number of coaxial connecting said one output terminal of each safety explosion爆回path to the signal line of the hazardous area, respectively And an n-type terminal which is mounted on each of the m wiring boards and which connects the other input / output terminal of each of the safety explosion-proof circuits to a signal line of a general circuit. a general circuit connector type terminal, the provided in each of the m wiring board, wherein the n number of the safety proof爆回path co <br/> through the ground terminal to connect to external collectively each ground terminal , attached to the case, before Symbol Common ground Set type safety cage, characterized by comprising the intrinsically safe ground terminal for connecting the child to an external common potential point, a.