JPS5832461Y2 - safety retainer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a safety keeper, and more particularly to a safety keeper configured to be detachable with a connector.

A safety keeper is inserted into a signal line between a hazardous area at a site and a control room in a non-hazardous area in order to make the instrumentation of a chemical plant or the like an intrinsically safe explosion-proof system.

The intrinsic safety of the system depends on the reliability of the safety barrier.

For this reason, explosion-proof standards require redundant design in which elements that constitute the circuit of the safety barrier and are directly related to safety maintenance, such as Zener diodes for voltage limitation, are duplicated.

At the same time, circuit redundancy is also checked at the start of operation and during periodic inspections.

For this reason, in recent safety keepers, the electric circuit including the safety maintaining element is used as a barrier unit, the terminal portion of the externally connected non-bonded side terminal and the safe side terminal is separated as a terminal unit, and the barrier unit and the terminal unit are connected by a connector. It is configured to be detachable and easy to perform maintenance and inspection.

At this time, the fuse is usually integrally molded with an insulating resin or the like inside the barrier unit together with the safety maintaining element, so if the fuse blows out, the entire barrier unit must be replaced, which is not economical.

In order to eliminate such drawbacks, conventionally, as shown in FIG.
is installed on the top surface of the barrier unit BU, and the barrier unit) B
The structure is such that the fuse unit (FU) can be attached and detached without removing the fuse unit (FU) from the terminal unit (TU), and when the fuse blows out, only the fuse unit (FU) can be replaced.
There are some that have improved economic efficiency.

By the way, when a fuse blows, it means that some kind of overvoltage has been applied to the safety barrier, so it does not mean that you can use it as is by just replacing the fuse, but rather check whether the barrier unit BU is normal or not before replacing the fuse. It should be replaced.

Therefore, in the case where the fuse unit (FU) is provided on the top surface of the barrier unit (BU) as in the past, the barrier unit (BU) is
There is a risk of replacing the fuse without inspecting the BU.

The present invention provides a safety retainer in which only the fuse can be replaced, and the barrier unit is less likely to be forgotten when replacing the fuse.

That is, the present invention has a terminal unit TUVC//'i as shown in the perspective view of FIG. 2 and the electrical connection diagram of FIG.
Terminal A, non-secured terminal B1 socket of connector a, socket of connector g, and one side h of fuse holder H.
0, and the barrier unit BU is provided with a Zener diode D1.0 as a voltage limiting element. D2, resistance R1 which is a current limiting element, inspection resistance r, pin of connector a, connector g
The other pin h2 of the fuse holder H is provided together with the pin.

The terminal unit) TU is fixed to the busbar BB with screws (not shown) or the like.

Then, after inserting the fuse F into one side of the holder H, attaching the barrier unit (BU) to the terminal unit (TU), the fuse F is mechanically and electrically connected to the other side of the holder H, and an electric circuit as shown in Fig. 3 is formed. A safety barrier is formed.

The fixing screw N is a variable unit) BU is a terminal unit) T
In addition to fixing it to U, it also provides redundant grounding with connector g.

Divide the holder H that houses the fuse F in this way, and divide one side into a barrier unit (BU) and the other into a terminal unit (T).
Since the fuse F cannot be replaced unless the barrier unit BU is removed from the terminal unit TU, it is possible to reduce the chance of forgetting to inspect the barrier unit BU when replacing the fuse.

Moreover, the fuse F also serves as a connector for connecting the barrier unit BU and the terminal unit TU, so that the number of connectors for connecting the barrier unit BU and the terminal unit TU can be reduced.

In the above-mentioned embodiment, the case where the inspection resistor r is included as the barrier unit BU is illustrated, but as shown in FIG. and connector C1
, C2, the inspection resistor r can be omitted and the problem of voltage drop due to r can be eliminated, and the Zener diodes D 1 tD2 can be inspected under the same conditions as the operating state.

In addition, poor contact between connectors C and C2 is safe, similar to poor contact with connector a, and the use of connectors C1t and C2 has no effect on the intrinsically safe explosion-proof properties.

Furthermore, the safety maintaining elements are not limited to Zener diodes and current limiting resistors, but voltage limiting circuits and current limiting circuits may be used as necessary.

As explained above, according to the present invention, it is possible to obtain a safety retainer in which only the fuse can be replaced and there is less need to forget to inspect the barrier unit when replacing the fuse.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing an example of a conventional safety barrier, Figure 2 is a perspective view of an embodiment of the safety barrier of the present invention, and Figure 3 is an electrical diagram of an embodiment of the safety barrier of the present invention. Connection diagram: FIG. 4 is an electrical connection diagram showing another embodiment of the safety barrier of the present invention. BU... Barrier unit, TU... Terminal unit, F... Fuse, Dl, D2...
... Zener diode, R ... Current limiting resistor, r ... Inspection resistor, H ... Fuse holder, a, C1, C2 ... ·connector.

Claims (1)

[Scope of utility model registration request] In a safety retainer in which a barrier unit containing a safety retaining element and a terminal unit containing external connection terminals on the safety side and non-safety side can be attached and detached using a connector, the holder that houses the fuse is divided and one side is attached to the barrier unit. and the other is provided on the terminal unit so that the fuse cannot be replaced without removing the barrier unit from the terminal unit.