CN212341277U

CN212341277U - 4-20mA current type analog quantity input/output disconnection-free measurement wiring terminal

Info

Publication number: CN212341277U
Application number: CN202021178213.0U
Authority: CN
Inventors: 李庆峰
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-06-23
Filing date: 2020-06-23
Publication date: 2021-01-12
Anticipated expiration: 2030-06-23

Abstract

The utility model belongs to the technical field of analog quantity wiring terminals, in particular to a 4-20mA current type analog quantity input and output disconnection-free measurement wiring terminal, which comprises a module body, wherein the module body is respectively provided with a first wiring terminal and a second wiring terminal, the first wiring terminal and the second wiring terminal are electrically connected through a conductive strip, a resistor which is connected with the conductive strip in parallel is arranged between the first wiring terminal and the second wiring terminal, the conductive strip electrically connects the first wiring terminal and the second wiring terminal under the compression of an elastic component, the first wiring terminal and the second wiring terminal are respectively provided with a measurement hole, the measurement hole is used for plugging a measurement needle of a measurement meter, the measurement needle is inserted into the measurement hole to compress the conductive strip to be separated from the first wiring terminal and the second wiring terminal, the wiring terminal has simple operation and flexible operation, is very beneficial to quick operation, on the premise of not interrupting the original signal, the current can be directly measured, and the acquisition and control of the system on the instrument signal are not influenced.

Description

4-20mA current type analog quantity input/output disconnection-free measurement wiring terminal

Technical Field

The utility model belongs to the technical field of analog quantity binding post, in particular to 4-20mA electric current type analog quantity input/output exempts from to tear open line and measures binding post.

Background

At present when the automatic control development of PLC is mature, 4-20mA analog quantity acquisition occupies the mainstream due to the advantages of stable signals, long distance and the like, and when the signals break down, the 4-20mA analog quantity needs to be measured and judged on line;

the detection of the analog quantity is divided into two types of voltage detection and current detection, namely 0-5V, 0-10V, 0-20mA, 4-20mA and the like, as shown in FIG. 6, and by adopting the voltage detection, a signal reaches the interior of the PLC, and the voltage signal can be directly converted into 32-bit digital quantity by an internal integrated block; when current detection is adopted, as shown in fig. 7, a 250-ohm sampling resistor needs to be connected in series, and the voltage of the resistor is converted into 32-bit digital quantity through an a/D module; at present, the method can only be used in a PLC module, when measuring current type analog quantity, an engineer needs to disconnect a channel circuit and connect a universal meter in series for measurement, when the channel circuit is disconnected, fault alarm can be caused, (voltage type analog quantity can be directly measured, but a voltage type analog quantity instrument is rarely used due to various defects, and the current type analog quantity instrument occupies the majority.

The traditional measuring operation modes include the following modes: a, connecting an ammeter in series after disconnecting for measurement; b, measuring the current at two ends of the fuse after the fuse is disconnected; c, measuring by adopting a special circuit wiring board or a special instrument; a. the b mode can generate signal alarm due to the disconnection of the original signal and can also cause misoperation. The mode c is inflexible, the circuit is complicated, the signal acquisition is influenced, the cost is high, and the use is less.

SUMMERY OF THE UTILITY MODEL

The utility model provides a 4-20mA electric current type analog quantity input/output exempts from to tear open line and measures binding post can solve the problem that points out among the background art.

The utility model provides a 4-20mA current type analog quantity input/output exempts from to tear open line and measures binding post, includes the module body, the module body is equipped with first wiring end and second wiring end respectively, through busbar electric connection between first wiring end and the second wiring end, still be equipped with the resistance that sets up with the busbar is parallelly connected between first wiring end and the second wiring end, the busbar is under elastomeric element's oppression, with first wiring end and second wiring end electric connection, be equipped with the measuring hole on first wiring end and the second wiring end respectively, the measuring hole is used for pegging graft the measuring needle of measuring gauge, and the measuring needle inserts oppress the busbar and separate with first wiring end and second wiring end in the measuring hole.

Preferably, the elastic member is a compression spring, the compression spring is located below the conductive strip, and the conductive strip is supported by the compression spring.

Preferably, the conductive bar is supported by compression springs located at two sides below the conductive bar, and the extended ends at two sides of the conductive bar are located below the measuring holes at two sides respectively.

Preferably, a conductive sliding body is arranged in the measuring hole.

Preferably, conductive contacts are respectively arranged between the conductive strip and the first terminal and between the conductive strip and the second terminal.

The utility model provides a 4-20mA electric current type analog quantity input/output exempts from to tear open line and measures special binding post, easy operation, the flexible operation does benefit to swift operation very much, under the prerequisite of not interrupting original signal, but direct measurement electric current size, collection and the control of not influence system to instrument signal.

Drawings

FIG. 1 is a schematic structural view of the present invention,

FIG. 2 is a schematic view of the normal usage state of the present invention,

FIG. 3 is a schematic view of the measurement state of the present invention,

FIG. 4 is a circuit diagram illustrating the normal operation state of the present invention,

FIG. 5 is a schematic diagram of the measurement status circuit of the present invention,

FIG. 6 is a schematic diagram of PLC voltage detection and current detection,

FIG. 7 is a schematic diagram of current sensing at the present stage,

description of reference numerals:

reference numbers in the figures: a module body 1; a first terminal 2; a second terminal 3; a measuring hole 4; a conductive strip 5; a resistor 6; an elastic member 7; measuring meter 8; a measuring needle 9; a conductive slider 10; conductive contacts 11.

Detailed Description

In the following, an embodiment of the present invention will be described in detail with reference to the drawings, but it should be understood that the scope of the present invention is not limited by the embodiment.

Example (b):

as shown in fig. 1-5, the utility model provides a special binding post is measured to 4-20mA (0-20mA) electric current type analog input/output disconnection-free, including module body 1, module body 1 is insulating material's preparation, for this binding post's support main part, module body 1 is equipped with first wiring end 2 and second wiring end 3 respectively, input and output, pass through busbar 5 electric connection between first wiring end 2 and the second wiring end 3, still be equipped with between first wiring end 2 and the second wiring end 3 with the resistance 6 that busbar 5 connects in parallel, be equipped with conductive contact 11 between busbar 5 and first wiring end 2 respectively with second wiring end 3, both sides conductive contact 11, the electric current passes through busbar 5; the conductive contacts 11 on the two sides are separated, and the current passes through the resistor 6; the conducting bar 5 is pressed by the elastic component 7 to electrically connect the first wiring terminal 2 with the second wiring terminal 3, the first wiring terminal 2 and the second wiring terminal 3 are respectively provided with a measuring hole 4, the measuring hole 4 is used for being plugged with a measuring needle 9 of a measuring meter 8 (universal meter), the measuring needle 9 is inserted into the measuring hole 4 to press the conducting bar 5 to be separated from the first wiring terminal 2 and the second wiring terminal 3, a conducting sliding body 10 is arranged in the measuring hole 4, the conducting sliding body 10 can slide up and down in the measuring hole 4, and the measuring needle 9 presses the conducting sliding body 10 to move downwards to drive the conducting bar 5 to move downwards, so that the conducting bar 5 is separated from the first wiring terminal 2 and the second wiring terminal 3.

The elastic part 7 is preferably a compression spring, the compression spring is positioned below the conductive strip 5, the conductive strip 5 is supported by the compression springs positioned at two sides below the conductive strip, and the extended ends at two sides of the conductive strip 5 are respectively positioned below the measuring holes 4 at two sides.

The working principle or the using method of the wiring terminal comprises the following steps: referring to fig. 2, in normal use, the current analog signal is input from the first terminal 2, output from the second terminal 3 through the conductive strip 5, and enter the PLC through the conductive wire, and this terminal is used as a normal terminal.

Referring to fig. 3, 4 and 5, a measuring method of a connection terminal includes the following steps:

firstly, beat direct current voltage gear to meter 8 (universal meter), measure needle 9 and inject two measuring holes 4, exert force gently, make busbar 5 break away from with first wiring end 2 and second wiring end 3, analog quantity current signal can be by the input of first wiring end 2, through resistance 6, by the output of second wiring end 3, the voltage of 5 both ends of resistance can be measured out to meter 8 (universal meter) this moment.

Converting the actual current (unit mA) in the circuit according to ohm's law, I = U/R;

and thirdly, after the measurement is finished, the measuring needle 9 of the measuring meter 8 (universal meter) withdraws, and the reset circuit of the conductive bar 5 recovers the normal working state under the action of the spring.

The utility model discloses a theoretical foundation: the method is characterized in that a resistor 6 is serially connected into a channel by imitating the interior of a PLC, the voltage of the resistor 6 is measured, the resistance value of the resistor is known, the current in the channel is calculated according to the ohm law I which is U/R, and the current can be directly obtained on the premise of not interrupting an original signal.

The above is only theoretically achievable, and in practice, two factors need to be considered: 1. selecting a resistor; 2. influence on the original circuit, 3, detailed operation.

Firstly, the resistor is selected, although 4-20mA (0-20mA) is a constant current source, the voltage on the resistor is increased proportionally with the increase of the circuit resistance, so that the working voltage obtained by the instrument is lower and lower, when the voltage of the instrument is lower than 18V, the instrument can not work, the power supply is generally 24V, the field measurement is generally 22-23V, (the load is large, and most of the load is less than 24V). The voltage drop across the resistor is in the range of 23-18 to 5V, and the voltage drop across the wires is also taken into account, so the series resistance drop cannot exceed 3V, and beyond this value, the meter may not operate due to insufficient supply voltage. And (3) converting R-U/I-3V/20 mA according to a formula of ohm law, and calculating the resistance to be 150 ohm at most. In this range, an interesting problem is found when a standard resistance of 100 ohms is chosen, the measured voltage and the actual current having the correspondence described in the graph,

that is, when a 100 ohm standard resistor is connected in series in the current-mode analog quantity channel, the measured voltage value is multiplied by 10, which is exactly the actual current value in the circuit, and is very convenient.

It has been seen from the above discussion that connecting 100 ohms of standard resistor in series in the current-mode analog channel will not affect the circuit, but in actual operation, connecting 100 ohms in series will undoubtedly increase an unstable factor, and the measurement is accidental after all, so a resistor short-circuit device is added in the circuit, through the terminal, the resistor 6 can be connected in series during measurement, the resistor 6 is not connected in series during normal operation, the normal operation of the circuit is not affected, and when the measurement is needed, the measurement can be carried out easily without worrying about measurement faults.

The above disclosure is only for a few specific embodiments of the present invention, however, the present invention is not limited to the embodiments, and any changes that can be considered by those skilled in the art shall fall within the protection scope of the present invention.

Claims

1. A4-20 mA current type analog quantity input and output disconnection-free measuring wiring terminal comprises a module body (1), wherein the module body (1) is provided with a first wiring terminal (2) and a second wiring terminal (3) respectively, and is characterized in that the first wiring terminal (2) is electrically connected with the second wiring terminal (3) through a conductive bar (5), a resistor (6) which is connected with the conductive bar (5) in parallel is further arranged between the first wiring terminal (2) and the second wiring terminal (3), the conductive bar (5) electrically connects the first wiring terminal (2) with the second wiring terminal (3) under the compression of an elastic component (7), measuring holes (4) are respectively arranged on the first wiring terminal (2) and the second wiring terminal (3), the measuring holes (4) are used for inserting measuring pins of a meter, and the measuring pins inserted into the measuring holes (4) press the conductive bar (5) to be connected with the first wiring terminal (2) and the second wiring terminal (3) separately And (5) separating.

2. The 4-20mA current mode analog quantity input and output disconnection-free measurement wiring terminal as claimed in claim 1, wherein: the elastic part (7) is a compression spring, the compression spring is positioned below the conductive strip (5), and the conductive strip (5) is supported by the compression spring.

3. The 4-20mA current mode analog quantity input and output disconnection-free measurement wiring terminal as claimed in claim 2, wherein: the conductive strip (5) is supported by compression springs positioned on two sides below the conductive strip, and the extension ends on two sides of the conductive strip (5) are respectively positioned below the measuring holes (4) on two sides.

4. The 4-20mA current type analog quantity input and output disconnection-free measurement wiring terminal as claimed in any one of claims 1-3, wherein: and a conductive sliding body (10) is arranged in the measuring hole (4).

5. The 4-20mA current type analog quantity input and output disconnection-free measurement wiring terminal as claimed in any one of claims 1-3, wherein: and conductive contacts (11) are respectively arranged between the conductive strip (5) and the first terminal (2) and between the conductive strip and the second terminal (3).