KR101657573B1

KR101657573B1 - R/i converter, level transmitter and auto setting method

Info

Publication number: KR101657573B1
Application number: KR1020160018596A
Authority: KR
Inventors: 김종호
Original assignee: 김종호
Priority date: 2016-02-17
Filing date: 2016-02-17
Publication date: 2016-09-19
Also published as: WO2017142107A1

Abstract

An R / I converter and a level transmitter having the same are disclosed. According to an aspect of the present invention, a resistance value of a sensor circuit varying according to a water level is converted into a current signal of a predetermined range, and the current signal is output to an external system through a current loop. A connector having a system input port to which an input terminal of the external system is connected and a system output port connected to an output terminal of the external system to output the converted current signal; And a bridge diode having a first input terminal connected to the system input port and a second input terminal connected to the system output port and connected to the device internal circuit through first and second output terminals, A converter may be provided.

Description

R / I converter, level trans- mitter, and auto-setting method

The present invention relates to an R / I converter, a level trans- mitter, and an auto-setting method. More particularly, the present invention relates to a level transmitter capable of measuring a fluid level, / I converter, and a level transmitter or an R / I converter.

Generally, the level measuring device or level transmitter (Level Transmitter) is structured to have various mechanisms depending on the place of installation and the purpose of use. It is widely used in washing machines, boilers, water tanks, Oil tanks of oil tankers, storage tanks of various factory facilities, and the like.

As an example of such a level gauge or level transmitter, there is known a pressure detection method in which a pressure transducer is installed on the upper surface of a stored fluid to measure a pressure change due to the increase or decrease in the volume of the contents and to detect a change amount of the water level. There is also a buoy system in which a buoy is placed on the water surface of the tank and a buoy is connected to a balance weight on the outside of the tank and the change of the balance weight is converted into an electrical signal and detected. However, there is a problem that an error occurs due to temperature or pressure change inside the tank due to the pressure detection method such as an electron, and the latter buoy system also has a problem that installation difficulty and precision are lacking in connection between the buoy and the balance weight .

Another method of water level measurement is a laser method in which a buoy is placed on a stored fluid and a change in the position of a buoy is measured by a laser or a water level of a fluid is directly measured by a laser, Photoelectric type and the like are known. These methods show good performance in terms of precision but have a very high product price and have a limitation in installation in explosion-proof areas such as oil tanks.

Therefore, a method using a magnetic floater in a manner that can be widely applied at a lower cost is known. This is because the magnetic floater is moved along the pipe along which the reed switch is longitudinally arranged and the change of the water level is detected as the reed switch is turned on and off. The total resistance value varies depending on the position of the reed switch to be turned on / off, And outputs it as data.

When the magnetic plotter system is connected to an external system such as a factory automation facility, the drive power is applied from an external system and a change in resistance value according to the water level is output as a predetermined electric signal. And is configured to receive sensing information by a current signal within a certain range. Therefore, in the case of the magnetic floater method, the change of the resistance value according to the water level is converted into a current signal required by the facility through a converter or the like and then outputted.

Embodiments of the present invention are intended to provide an R / I converter and a level transmitter capable of normal operation of the device even when the input and output terminals are incorrectly connected to the external system by a user.

Embodiments of the present invention also provide an R / I converter and a level transmitter capable of checking the output current without disconnection of the output cable under normal operating conditions.

In addition, embodiments of the present invention provide an auto-setting method that allows a user to set a water level measurement range of the R / I converter or a level transmitter without knowing the level range of the fluid to be measured by the user.

According to an aspect of the present invention, a resistance value of a sensor circuit that varies according to a water level is converted into a current signal of a predetermined range and is output to an external system through a current loop, A system input port to which an input terminal of the external system is connected, and a system output port connected to an output terminal of the external system to output the converted current signal; And a bridge diode having a first input terminal connected to the system input port and a second input terminal connected to the system output port, the bridge diode being connected to the device internal circuit through first and second output terminals An R / I converter may be provided.

According to another aspect of the present invention, there is provided a semiconductor device comprising: a guide pipe having a plurality of resistors arranged in series and a reed switch disposed between the resistors; A magnetic floater moved on the guide pipe according to the water level to switch on the reed switch; And a level transmitter including the R / I converter.

According to another aspect of the present invention, there is provided a method for automatically setting a water level measurement range of a level transmitter including a plurality of resistors arranged in series and a reed switch disposed between the resistors, Measuring a voltage across the connected series resistor; Calculating a current flowing through the series resistor; Calculating a total resistance of the sensor circuit; Calculating the number of resistances based on the calculated total resistances; And calculating a measured voltage according to the maximum and minimum levels based on the number of resistors and allocating the measured voltage to a preset output current range.

The R / I converter and the level transmitter according to the embodiments of the present invention are configured such that the input and output terminals of the external system are connected to the internal circuit through the bridge diode so that even when the operator connects the input and output terminals in reverse, And it is possible that it is a normal operation. Therefore, it is possible to minimize the damage or malfunction of the device due to miswiring.

In the R / I converter and the level transmitter according to the embodiments of the present invention, the test port drawn from the second output terminal of the bridge diode is provided in the connector, so that the system output You can check the output current by connecting an ammeter to the terminal and test port. Therefore, it is possible to easily check the output current even in a normal operating state without stopping the operation of the equipment, and the usability can be increased.

In addition, the autosetting method according to the embodiments of the present invention allows the user to set the water level measurement range by himself / herself through the auto setting in the field even when the operator does not know the capacity or the water level range of the tank to be measured . Therefore, convenience of operation can be improved, and malfunction due to setting error or the like can be prevented.

1 is a schematic diagram showing a level transmitter according to an embodiment of the present invention.
2 is a conceptual diagram for explaining the operation of the level transmitter shown in FIG.
3 is an external view of the R / I converter shown in FIG.
4 is a block diagram schematically showing an internal configuration of the R / I converter shown in FIG.
5 is a circuit diagram showing a part of the circuit structure of the protector shown in Fig.
6 is a circuit diagram showing the bridge diode shown in Fig.
7 is a flowchart illustrating an autotating method according to an embodiment of the present invention.
8 is a circuit diagram for implementing the autotating method of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It is to be understood, however, that the following examples are provided to facilitate understanding of the present invention, and the scope of the present invention is not limited to the following examples. In addition, the following embodiments are provided to explain the present invention more fully to those skilled in the art. Those skilled in the art will appreciate that those skilled in the art, Will be omitted.

1 is a schematic diagram showing a level transmitter 100 according to an embodiment of the present invention.

1, a level transmitter 100 according to an embodiment of the present invention may be installed through a flange structure 110 at a top portion of a tank T and includes a guide pipe 120 may be provided. The guide pipe 120 is formed to extend from the bottom of the tank T to a length sufficient to reach the top of the top of the tank T and may be disposed in a substantially vertical direction or up and down direction within the tank T. [

The level transmitter 100 may include a magnetic floater 130. The magnetic floater 130 may be installed on the guide pipe 120 so as to be movable along the guide pipe 120 and may be moved up and down along the guide pipe 120 according to the water level in the tank T. [ The magnetic floater 130 may be formed to float on the fluid stored in the tank T for movement along the water level, and may include at least one magnetic body. The magnetic body moves together with the magnetic floater 130 to turn on / off the reed switch L to be described later.

The upper structure of the level transmitter 100 may be exposed to the outside of the tank T. [ In other words, the upper side of the flange structure 110 provided at the top of the tank (T) can be exposed outside the tank (T). The upper structure of the level transmitter 100 may include an R / I converter 140. The resistance value of the R / I converter 140 according to the water level in the tank T is received by the guide pipe 120 and the magnetic floater 130. The R / I converter 140 converts the resistance value into a current value in the set range, have.

For example, when the level transmitter 100 according to the present embodiment is installed in a part of factory automation equipment, the R / I converter 140 can transmit the level information (current signal) in the tank T to the automated facility , The automated facility may perform appropriate automated control (e.g., pump drive) according to the water level information. Hereinafter, for convenience of explanation, the case where the level transmitter 100 according to the present embodiment is associated with a factory automation facility will be described. However, the level transmitter 100 or the R / I converter 140 according to the present embodiment may be applied to various fields as a means for measuring the level in the tank T or a means for converting a resistance value into a current signal, The present invention is not limited to application to factory automation facilities.

2 is a conceptual diagram for explaining the operation of the level transmitter 100 shown in FIG.

2 (a), the guide pipe 120 includes a plurality of reed switches L, a plurality of reed switches L, and a plurality of reed switches L, And the plurality of reed switches L may be spaced apart at regular intervals along the longitudinal direction of the guide pipe 120. [ The magnetic floater 130 may be moved up and down according to the fluid level to switch on the reed switch L at the corresponding position. In other words, each of the reed switches L is in the off state, and can be switched on by the reed switch L when the magnetic floater 130 comes to the corresponding position. The guide pipe 120 can generate a variable resistance value by on / off operation of the reed switch L. [ That is, the guide pipe 120 generates a resistance value corresponding to the fluid level in the tank T according to on / off of each reed switch L. [

2 (b) is a schematic diagram showing a resistance value change according to the movement of the magnetic floater 130. Referring to FIG. 2, the guide pipe 120 includes a plurality of resistors R connected in series at regular intervals along the longitudinal direction, The reed switch L disposed between the resistors R can constitute one sensor circuit SC. Each of the reed switches L is in the off state and when the magnetic floater 130 is at the corresponding position, the reed switch L is switched on so that the sensor circuit SC is short-circuited at the corresponding position, ), That is, depending on the water level, a different resistance value can be generated in the sensor circuit SC.

Also, the resistance value information generated according to the water level can be transmitted to the R / I converter 140 through the sensor output terminal C '. In FIG. 2B, H denotes a sensor input terminal H 'for inputting driving power to the sensor circuit SC, and L denotes a ground terminal L' for earth. The sensor output terminal C ', the sensor input terminal H', and the ground terminal L 'may be configured as a constant current source (for example, a constant current source of two transistors of the transistor) May be connected to the connector 143 of the R / I converter 140, which will be described later.

FIG. 3 is an external view of the R / I converter 140 shown in FIG. 1, and FIG. 4 is a block diagram schematically showing an internal configuration of the R / I converter 140 shown in FIG.

Referring to FIGS. 3 and 4, the R / I converter 140 may be disposed at the upper end of the guide pipe 120 or the like and connected to the sensor circuit SC. The R / I converter 140 receives the resistance value information changed according to the water level through the sensor output terminal C ', converts the resistance value into a current signal in a range required by the external system, and transmits the current signal to the external system.

For example, in the factory automation equipment illustrated in the present description, a 24 V input power is supplied to the R / I converter 140, and the R / mA, and then transmits (outputs) the current signal to the automation equipment. In other words, the R / I converter 140 receives the series resistance change value in the guide pipe 120 according to the on / off state of the reed switch L and outputs it as a current signal of 4 to 20 mA . The method of converting an input voltage into a current signal in a predetermined range according to a sensor value and outputting the current signal is called a current loop method in the related art.

4, the R / I converter 140 includes a sensor unit 141 for receiving sensing information according to a change in the level of water from the guide pipe 120, and a sensing unit 141 for outputting sensed data with a current signal of 4 to 20 mA A connector 143 to which an input / output cable or the like is connected, a protector 144 for electrostatic discharge (ESD) or surge protection, and the like.

The R / I converter 140 further includes a key module 147 including a microprocessor 145 as a main control processor, an X-TAL 146 for time synchronization, a mode switch 147a, and a setting switch 147b. An LED indicator 148 for indicating the status of the apparatus, a power unit 149 for supplying driving power to the apparatus, a J-TAG 141-1 for downloading and debugging the program, a communication means A UART 142-1, and the like.

As shown in FIG. 3, the connector 143 may include a system input port (+) to which an input terminal of an automation equipment (external system) is connected and a system output port (-) to which an output terminal is connected. The driving power of a predetermined voltage (usually DC +24 V) may be input from the automation equipment to the system input port (+). In the system output port (-), a current of 4 to 20 mA A signal can be output (Current loop). The connector 143 may have a sensor input port H, a sensor output port C and a grounding port L connected to the sensor circuit SC in the guide pipe 120. The sensor output terminal C 'is connected to the sensor input port H', the ground terminal L 'is connected to the sensor output port C, and the ground terminal L' is connected to the sensor input port H ' Can be connected.

The R / I converter 140 receives a predetermined voltage from a factory automation facility or the like through a system input port (+). The R / I converter 140 outputs sensing information (SC)) into a current signal of a set range (4 to 20 mA), and outputs the current signal to the automatic facility again through the system output port (-). Since the input and output of the current loop type are known in the art and are distant from the technical point of the present invention, the detailed operation mechanism of the R / I converter 140 is not described here.

Fig. 5 is a circuit diagram showing a part of the circuit configuration of the protector 144 shown in Fig. 4, and Fig. 6 is a circuit diagram showing the bridge diode 150 shown in Fig.

Referring to FIGS. 5 and 6, the R / I converter 140 according to the present embodiment may include a bridge diode 150. More specifically, the R / I converter 140 according to the present embodiment may include a bridge diode 150 in a protector 144 for ESD, surge protection, and the like.

The bridge diode 150 may include first and second input terminals I1 and I2 and first and second output terminals O1 and O2. The first input terminal I1 may be connected to the system input port (+) of the connector 143 and the second input terminal I2 may be connected to the system output port (-). The first and second output terminals O1 and O2 may be connected to an internal circuit of the device to transmit an input voltage to the current loop unit 142 and receive an output current therefrom.

The bridge diode 150 as described above can be connected to the bridge 143 via the bridge 143. The bridge diode 150 can be connected to the bridge 143 via the bridge 143 The I / O converter 140 has no influence on the internal circuit, thereby preventing breakage or malfunction of the device due to miswiring. The input terminal is connected to the system output port (-) and the output terminal is connected to the system input port (-) as well as the normal connection state in which the input terminal is connected to the system input port (+ The first and second output terminals O1 and O2 are not affected by the bridge diode 150 even in the case of a misconnected state connected to the first and second output terminals O1 and O2 (b)).

3), and the test port TP is connected to a bridge diode (not shown). The R / I converter 140 according to the present embodiment may include a test port TP for measuring an output current in the connector 143 May be configured to be drawn out from the second output terminal (O2) of the second transistor (150). In such a case, the operator can confirm the output current by connecting an ammeter to the system output port (-) and the test port (TP) from the connector 143. In the case of a diode, which is a semiconductor element of a PN junction, a forward current flows in a direction from a P-type semiconductor to an N-type semiconductor (cathode). The electrons move in the + direction and the holes move in the - Since a depletion layer is formed on the PN junction, an electric current flows through the PN junction, but the resistance is infinite and serves as an opening of the wire.

Particularly, in such a case, there is an advantage in that the output current can be checked without disconnecting the output cable connected to the external system (automation equipment) by the characteristics of the bridge diode 150.

In addition, in order to check whether the device is normally operated, the output cable connected to the system output port (-) is disconnected and an ammeter is installed to check the output current. In this case, There is a problem that the operation is interrupted also in an external system such as an entire automation facility. On the other hand, in the case of the R / I converter 140 according to the present embodiment, the output current (-) can easily be outputted through the system output port (-) and the test port (TP) It is possible to solve the above-mentioned problem.

Meanwhile, if necessary, the R / I converter 140 or the level transmitter 100 according to the present embodiment may include an auto setting function for automatically setting the level range of the fluid to be measured. The autosetting function allows the user to automatically set the output value according to the maximum / minimum water level without the information on the capacity of the tank, the range of the fluid level, etc., and the automatic setting function can be performed by the microprocessor 145 of the R / Control algorithms. Hereinafter, the autosetting method will be described in detail with reference to the drawings.

FIG. 7 is a flowchart illustrating an auto setting method according to an embodiment of the present invention, and FIG. 8 is a circuit diagram for implementing the auto setting method of FIG.

7 and 8, an autotating method according to the present embodiment includes the steps of measuring voltages V1 and V2 across a series resistor Rt connected to a power supply line of a sensor circuit SC (see FIG. 2) S1). At this time, the step S1 may be started without filling the tank for the water level measurement, and the series resistance Rt may have a predetermined fixed value (for example, 1 k?) Reference). In this case, the current supplied to the sensor circuit SC and the current flowing through the series resistor Rt have the same value based on the law of conserving the amount of electric charge.

Also, the autotancing method according to the present embodiment may include a step S2 of calculating a current I flowing in the series resistor Rt. At this time, the current (I) can be calculated by the following formula (1).

[Expression 1] I = (V1 - V2) / Rt

In the calculation formula 1, I denotes a current value flowing through the series resistor Rt, V1 and V2 denote voltage values across the series resistor Rt, and Rt denotes a resistance value of the series resistor Rt. At this time, V2 can be known by the supply voltage to the sensor circuit SC.

On the other hand, the autotancing method according to the present embodiment may include the step S3 of calculating the total resistance Rs of the sensor circuit SC. At this time, the total resistance Rs can be calculated by the following formula 2.

[Expression 2] Rs = V2 / I

In the calculation formula 2, Rs denotes a total resistance value of the sensor circuit, V2 denotes a voltage value at one end of the series resistance Rt (or a supply voltage value to the sensor circuit SC), I denotes a series resistance Rt Current value "

The autosetting method according to the present embodiment may include a step S4 of calculating the number of resistances R of the sensor circuit SC from the total resistance Rs calculated in the above manner. At this time, each resistance R of the sensor circuit SC may have a preset fixed value Ro and may be arranged at a predetermined constant interval D. For example, each resistor R may be arranged at 10 mm intervals with a fixed value of 20 OMEGA. In this case, the number of the resistors R and the total resistance R of the sensor circuit SC are changed according to the water level measuring range. Therefore, the number of resistances R of the sensor circuit SC can be calculated by the following calculation formula 3.

[Expression 3] N = Rs / Ro

N is the number of the resistors R, Rs is the total resistance of the sensor circuit SC calculated in the preceding step, and Ro is the resistance value of each resistor R (fixed value).

Meanwhile, the auto-setting method according to the present embodiment calculates the measured voltage according to the maximum water level and the minimum water level based on the number of resistors N and allocates the measured voltage to a predetermined current range (for example, 4 to 20 mA) S5). That is, in this embodiment, each resistance R of the sensor circuit SC has a predetermined fixed value, so that it is possible to calculate the measured voltage according to the water level by knowing the number N of the total resistances. At this time, the minimum water level can be applied to a predetermined number (for example, ten) of resistances R from the lowermost stage, and the maximum water level can be applied from the uppermost stage And may be applied to a predetermined number (e.g., ten) of resistors R. In this step S5, the calculated maximum / minimum measured voltage is allocated to a current range required by an external system such as a factory automation facility to implement the auto setting function.

As described above, the autosetting method according to the present embodiment allows the user to set the water level measurement range by the auto setting in the field even when the operator does not know the capacity or the water level range of the tank to be measured do. Therefore, convenience of operation can be improved, and malfunction due to setting error or the like can be prevented.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, many modifications and changes may be made by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims. The present invention can be variously modified and changed by those skilled in the art, and it is also within the scope of the present invention.

100: Level transmitter T: Tank
110: flange structure 120: guide pipe
130: Magnetic plotter 140: R / I converter
L: Reed switch R: Resistance
SC: Sensor circuit C ': Sensor output terminal
H ': Sensor input terminal L': Ground terminal
143: connector 141:
142: current loop portion 143: connector
144: Protector 145: Microprocessor
146: X-TAL 147a: Mode switch
147b: Setting switch 147: Key module
148: LED indicator 149: Power indicator
151: J-TAG 152: UART
+: System input port -: System output port
H: Sensor input port C: Sensor output port
L: Ground port TP: Test port
150: bridge diode I1: first input terminal
I2: second input terminal O2: first output terminal
O2: second output terminal

Claims

delete

A method for automatically setting a level measuring range of a level transmitter including a plurality of resistors R arranged in series and a reed switch L disposed between the resistors R,
Measuring (S1) the voltages V1 and V2 across the series resistor Rt connected to the power supply line of the sensor circuit SC;
Calculating a current flowing through the series resistor (Rt) (S2);
Calculating (S3) the total resistance (Rs) of the sensor circuit (SC);
Calculating (S4) the number (N) of resistances (R) based on the calculated total resistance (Rs); And
Calculating a measured voltage according to the maximum and minimum levels based on the number of resistances (R) (N) and allocating the measured voltage to a predetermined output current range (S5).

The method of claim 4,
Wherein each of the resistors R is spaced apart by a predetermined distance D with a preset fixed value Ro.