JP4968579B2 - Field equipment - Google Patents

Description

  The present invention relates to a field device, and in particular, short-circuits or opens a power cable at an appropriate position of a cable ground that is a wiring component attached to a power connection port of a field device that does not have a function of turning on / off the power. The present invention relates to a field device having a structure provided with a switch means.

As shown in FIG. 5, in the field device in the prior art, a power terminal block 12 for connecting a power cable 11 is built in a field device case 13, and this field device case 13 is for supplying power from the outside. A cable entry portion 14 serving as a power connection port through which the power cable 11 is inserted, and a cable gland 15 for guiding the power cable 11 outside the case 13 and at a position closest to the cable entry portion 14. It has a configuration.
On the other hand, on the upper side of the power cable 11, there is a control instrument room area 16 for supplying power to the power cable 11. In the control instrument room area 16, the power source 17 and the power cable 11 are short-circuited or opened. The switch 18 is configured to be provided.
In the field device having such a configuration, when opening the cover of the field device and accessing the inside of the case 13, before opening the cover of the case 13 in order to prevent a spark such as a power line inside the case 13. The switch 18 in the control instrument room area 16 is opened, and the cover of the case 13 is opened after the power supply to the field device is cut off.

Japanese Patent Laid-Open No. 7-23509 (page 3, Fig. 2)

However, in the field device described in the prior art, when the field device opens the cover of the field device in a hazardous gas atmosphere area and accesses the inside of the case (setting change with switch, connection of power line, etc.) In addition, in order not to induce an explosion accident due to a spark such as a power supply line, it is necessary to always turn off the power supplied to the field device in the control instrument room area far from the field device.
As described above, there is a problem that the power line cannot be turned off at the installation site of the field device, and the power supply cannot be confirmed in the field device having no field indicator.

  Therefore, in the field where the field device is installed, there is a problem that must be solved by enabling the power ON / OFF on the upper side of the power line than the field device and visually confirming or confirming the power ON / OFF. Have.

  In order to solve the above problems, the field device of the present invention is configured as follows.

(1) The field device is built in the field device case and has a power terminal block for connecting a relay connection cable for supplying power, and a power connection port for inserting the relay connection cable for supplying the power. A cable entry portion, a relay connection cable terminal connected to a relay connection cable for supplying the power, a power supply cable terminal connected to a power cable, and the relay provided near the cable entry portion A field device including a cable ground provided with a wiring provided between the connection cable terminal and the power cable terminal , wherein the cable ground is provided between the connection cable terminal for the relay and the power cable terminal. The switch means for short-circuiting or opening the connected wiring is provided.

According to this proposal, even if the switch in the control instrument room area on the upper side of the power cable is in the energized state (ON), the power can be turned on / off at the cable ground of the field device. No need to operate the power supply.
In addition, since the power supply line to the field device can be turned on and off at the installation site, the field device can be wired while the power supply is surely turned off, and safe instrumentation can be realized. .

  Next, an embodiment of a field device according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected and demonstrated to the same thing as what was demonstrated by the prior art.

As shown in FIG. 1, the field device of the present invention has a power terminal block 12 for connecting a relay connection cable 19 connected to a power cable 11 in a field device case 13. The case 13 includes a cable entry portion 14 that is a power connection port for inserting a relay connection cable 19 for supplying power from the outside, and a power source is located outside the case 13 and in the immediate vicinity of the cable entry portion 14. The cable gland 15 for guiding the cable 11 is provided.
A relay connection cable 19 is inserted into the cable entry portion 14, and one end of the relay connection cable 19 is connected to the power terminal block 12.
The relay connection cable 19 is routed from the cable entry portion 14, and the other end is connected to the relay connection cable terminal 21 provided in the cable gland 15 arranged in the closest position of the cable entry portion 14. Has been.

  The cable gland 15 is provided at a position closest to the cable entry portion 14 and guides the power cable 11. The cable gland 15 is provided with a relay connection cable terminal 21 connected to the relay connection cable 19 on the cable entry portion 14 side. The power supply cable terminal 22 is connected to the power supply cable 11 at a distance.

A switch means 23 for short-circuiting or opening the power cable 11 is provided between the relay connection cable terminal 21 and the power cable terminal 22.
The switch means 23 includes a switch 24 that opens and closes one of the two wires provided between the terminals 21 and 22.

  On the other hand, there is a control instrument room area 16 for supplying power to the field device at a position far from the field device, and power supply to the field device is turned ON / OFF in the control instrument room area 16. The switch 18 is provided. The switch 18 is configured to be able to turn on / off the power supply to the field device in the same manner as described in the prior art.

  In the field device having such a configuration, when a power ON / OFF operation occurs inside the field device, the cable ground in the immediate vicinity of the field device is not turned on / off without turning on / off the switch 18 in the control instrument room area 16. The power supply to the field device can be controlled by turning on / off the switch 24 of the switch means 23 provided in the circuit 15.

  This is because when the field device is opened in the hazardous gas atmosphere area and the work to access the inside of the case 13 by opening the cover of the field device (changing the setting with the switch, connecting the power line, etc.) In order to prevent the occurrence of explosion accidents, the power supply to the field device must be turned off in the control instrument room area 16 installed far away from the field device. By turning ON / OFF a certain switch 24, the work can be smoothly performed on the site without going to the remote control instrument room area 16.

In FIG. 2, a timer function 25 is added to inform the cable gland 15 of the elapsed time after the energization ON / OFF switch operation.
A timer function 25 is added to the one described in FIG. 1 above. In a field device, a specification device that needs to wait for a certain time when performing wiring work after power OFF, for example, the temperature of electrical components inside the device In consideration of the case where it is used for a field device having a waiting time limit for opening and closing the cover (= wiring work) due to the energy of the rise and capacitance, a configuration is provided in which the timer function 25 is provided in the cable gland 15.

  Thus, for example, a function for notifying the elapse of a predetermined time after the power is turned off, such as LED display and beep sound, enables the worker to perform safe wiring work in accordance with the specifications of the device.

In FIG. 3, an operation error prevention function 26 is added to the switch 24 of the switch means 23 of the cable gland 15.
The structure described in FIG. 1 is added with an erroneous operation prevention function 26, so that the switch operation portion can be accessed only with a special tool so that the switch 24 of the switch means 23 included in the cable gland 15 cannot be operated by mistake. To do. As another method, the switch operation unit is provided with a password function so that it can be operated only by a specific person to prevent erroneous operation.

In FIG. 4, a display function 27 is added to the switch means 23 of the cable gland 15 so that the energized state can be seen.
In the case where the display function is added to the one described with reference to FIG. 1 and the field device itself has no LCD display, the energized state cannot be confirmed at the installation site. As a means for confirmation on site, a display function 27 such as an LED lamp is provided on the cable gland 15 so that the presence / absence of an energized state can be displayed for visual recognition.

  Provided is a field device that enables power ON / OFF at a cable ground of a field device even when a switch in the control instrument room area on the upper side of the power cable is in an energized state (ON).

It is explanatory drawing which showed schematically the field apparatus of this invention. It is explanatory drawing which showed schematically the field apparatus which added the timer function similarly. It is explanatory drawing which showed schematically the field apparatus which added the incorrect operation prevention function of the switch similarly. It is explanatory drawing which showed schematically the field apparatus which added the timer function similarly. It is explanatory drawing which showed schematically the field apparatus in a prior art.

Explanation of symbols

11 Power cable 12 Power terminal block 13 Field device case 14 Cable entry 15 Cable gland 16 Control instrument room area 17 Power supply 18 Switch 19 Relay connection cable 21 Relay connection cable terminal 22 Power cable terminal 23 Switch means 24 Switch 25 Timer function 26 Misoperation prevention function 27 Display function

Claims (1)

A power terminal block that is built in the field device case and connects a connection cable for relay to supply power,
A cable entry portion which is a power connection port through which the relay connection cable for supplying the power is inserted;
The relay connection cable terminal connected to the relay connection cable for supplying the power, the power supply cable terminal connected to the power cable, and the relay connection cable terminal and the power source provided at a position closest to the cable entry portion A cable gland with wiring provided between the cable terminals;
A field device comprising:
A field device characterized in that the cable ground is provided with switch means for short-circuiting or opening the wiring provided between the connecting cable terminal for relay and the power cable terminal .

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