CN204374273U - A kind of handheld digital secondary pressure plate measuring instrument - Google Patents

Abstract

A hand-held digital secondary pressure plate measuring instrument, including a hand-held housing, a test circuit installed in the housing, and a display screen, the measuring instrument has three measuring probes, and the testing circuit includes a power supply module, a voltage measurement module and a display module , the power supply module provides a stable power supply VCC, each module is connected with the single-chip microcomputer U, and the voltage test module includes two addition measurement circuits, wherein two measurement probes are connected with the two addition measurement circuits for contacting with the secondary pressure plate measurement port, in addition One measuring lead is grounded. The utility model is easy to use, and is suitable for measuring the secondary pressure plate of a device powered by DC plus or minus 110V, plus or minus 55V, or plus or minus 24V. It can simultaneously measure the voltage at both ends of the secondary pressure plate to ground, and intelligently judge whether it meets the input conditions of the pressure plate. And it adopts a hand-held design, which is flexible and convenient, effectively improving the efficiency of secondary platen voltage measurement and reducing misoperation accidents.

Description

A hand-held digital secondary platen measuring instrument

technical field

The utility model relates to the improvement of the secondary pressure plate measurement technology.

Background technique

In order to prevent accidental tripping of power transmission and transformation equipment due to errors when measuring the voltage of the relay protection or the secondary pressure plate of the automatic device, the on-site operating regulations stipulate that the ground voltage at both ends of the pressure plate must be measured before the pressure plate is put into operation. However, in actual operation, the wrong outlet trip accident of the device was caused by the wrong gear selection of the multimeter and the operating personnel's unfamiliarity with the input conditions of the secondary pressure plate. In addition, when using an ordinary multimeter to measure the voltage of the secondary platen, you can only measure one end and then the other end, which is not efficient.

Contents of the invention

In order to overcome the deficiencies in the prior art, the purpose of this utility model is to provide a hand-held digital secondary platen measuring instrument that is easy to use and can not be misoperated.

In order to solve the above problems, the technical scheme adopted by the utility model is as follows:

A hand-held digital secondary pressure plate measuring instrument, including a hand-held housing, a test circuit installed in the housing, and a display screen, the measuring instrument has three measuring probes, and the testing circuit includes a power supply module, a voltage measurement module and a display module , the power supply module provides a stable power supply VCC, each module is connected with the single-chip microcomputer U, and the voltage measurement module includes two addition measurement circuits, wherein two measurement probes are connected with the two addition measurement circuits for contacting with the secondary platen measurement port, in addition One measuring lead is grounded.

Wherein, the addition measurement circuit includes a binding post connected to the measuring pen, the binding post is connected to the non-inverting input terminal of the operational amplifier 1 through the piezoresistor R5 and a plurality of voltage dividing resistors, and the output terminal of the operational amplifier 1 is passed through a fast-blow fuse F is connected with the input pin VTest of the one-chip computer U.

Wherein, the U input pin VTest of the single-chip microcomputer is grounded through two capacitors C1 and C2 connected in parallel; , the node between the resistor R1 and the resistor R2 is grounded through the parallel capacitor C3, the polarized capacitor C4 and the resistor R4, and the terminal is grounded through the piezoresistor R5; the reverse input terminal of the operational amplifier is grounded through the resistor R6 and the resistor R7 respectively. The output terminal is connected; the operational amplifier is connected to the input terminal through the resistance R8 and the second output terminal of the operational amplifier, the two input terminals of the operational amplifier are connected to the adjustable voltage input circuit, and the negative input terminal of the operational amplifier is connected to the output terminal.

Among them, the adjustable voltage input circuit includes resistors R9 and R10 connected in series between the power supply VCC and the ground, and an adjustable resistor R11 is connected in series between the power supply VCC and the ground, and the movable end of the adjustable resistor R11 is connected to the operational amplifier. to the input and between resistor R9 and resistor R10.

Moreover, the power supply module includes a self-locking switch S0 connected to the two poles of the battery and the power supply VCC terminal, and the power supply VCC is grounded through the capacitor C5, the capacitor C6 and the piezoresistor R12 connected in parallel.

The utility model is easy to use, and is suitable for measuring the secondary pressure plate of a device powered by DC plus or minus 110V, plus or minus 55V, or plus or minus 24V. It can simultaneously measure the voltage at both ends of the secondary pressure plate to ground, and intelligently judge whether it meets the input conditions of the pressure plate. And it adopts a hand-held design, which is flexible and convenient, effectively improving the efficiency of secondary platen voltage measurement and reducing misoperation accidents.

Description of drawings

Figure 1 is a schematic diagram of the overall appearance of the utility model embodiment.

FIG. 2 is a schematic diagram of the addition measurement circuit of this embodiment.

Fig. 3 is a circuit diagram of the power supply module of this embodiment.

Fig. 4 is the schematic diagram of the peripheral circuit of the single-chip microcomputer U of the present embodiment.

Fig. 5 is a schematic diagram of the display module of this embodiment.

Detailed ways

In order to allow those skilled in the art to better understand the technical solution of the utility model, the utility model will be further elaborated below in conjunction with the accompanying drawings.

As shown in Figure 1. The hand-held digital secondary platen measuring instrument disclosed in this embodiment is a small secondary platen measuring instrument that is easy to carry. Measuring leads (not shown in the figure). Wherein, the display screen 11 realizes data display through the display module, and the specific circuit schematic diagram of the display module can be shown in Fig. 5 , which will not be described in detail here. The test circuit includes a power supply module and a voltage measurement module. The power supply module provides a stable power supply VCC, and each module is connected to the single-chip microcomputer U. The voltage measurement module includes two addition measurement circuits, two of which are connected to the two addition measurement circuits for contact with the secondary pressure plate measurement port, and the other measurement pen is grounded. During normal use, the two measurement leads are connected to the addition measurement circuit. The connected measuring probe is inserted into the measuring port of the secondary pressure plate, and the other probe is connected to the grounding wire of the relay protection or automatic device. The single-chip microcomputer U measures the voltage input by the two addition measurement circuits, and the two ends of the pressure plate are respectively connected to the ground. Voltage, and judge whether it meets the input conditions.

In this embodiment, the single-chip microcomputer U can be an LQFP48 single-chip microcomputer, and its peripheral circuit is shown in FIG. 4 , which will not be repeated here.

At the same time, 8 LED indicator lights 2 are also arranged on the front of the shell 1. The display screen 11 is used to display the voltage measured by the single-chip microcomputer and to indicate whether the display meets the input conditions of the pressure plate. The 8 LED indicator lights 2 are divided into two lines and are on and off Controlled by the single-chip microcomputer U, the upper line is 0V, +24V, +55V, +110V, and the lower line is 0V, -24V, -55V, -110V. For example, one measuring pen measures +55V, and the other measures -55V. Then the +55V and -55V LED indicators are on, but the 0V LED is divided into the meter pen. The upper 0V LED indicator represents the 0V voltage measured by the left measurement pen, and the lower 0V LED indicator represents the right one. The voltage measured by the test leads.

In this embodiment, as described in accompanying drawing 2. The designed addition measurement circuit is used to compare and convert the voltage value measured by the test pen into a signal acceptable to the single-chip microcomputer U, and display the test result on the display screen 11 through the internal processing of the single-chip microcomputer U. The addition measurement circuit includes a terminal 12 (located above the shell 1) connected to the measuring pen, the terminal 12 is connected to the non-inverting input terminal of the operational amplifier 1 through the piezoresistor R5 and a plurality of voltage dividing resistors, and the output terminal of the operational amplifier 1 The fast-blow fuse F is connected to the U input pin VTest of the single-chip microcomputer. The varistor R5 can prevent input overvoltage, and the fast-blow fuse F is to prevent the internal short circuit of the single-chip microcomputer from conducting and grounding. The single-chip microcomputer U input pin VTest is grounded through two capacitors C1 and C2 in parallel; The node between the resistors R2 is grounded through the capacitor C3, the polarized capacitor C4, and the resistor R4 connected in parallel, and the terminal is grounded through the piezoresistor R5; the reverse input terminal of the operational amplifier is connected to the output terminal through the grounding of the resistor R6 and the resistor R7 respectively; The input end of the operational amplifier is connected with the second output end of an operational amplifier through a resistor R8, the second input end of the operational amplifier is connected with an adjustable voltage input circuit, and the reverse input end of the operational amplifier is connected with its output end. Among them, the adjustable voltage input circuit includes resistors R9 and R10 connected in series between the power supply VCC and the ground, and an adjustable resistor R11 is connected in series between the power supply VCC and the ground, and the movable end of the adjustable resistor R11 is connected to the operational amplifier. to the input and between resistor R9 and resistor R10.

As shown in Figure 3, the power supply module designed in this embodiment includes a self-locking switch S0 connected to the two poles of the battery and the power supply VCC terminal, and the power supply VCC is grounded through parallel-connected capacitors C5, C6 and varistor R12.

The hand-held digital secondary platen measuring instrument disclosed in this embodiment adopts a hand-held design, is flexible to use, and is very convenient to operate, which can effectively improve measurement efficiency and reduce misoperation. And it can measure the ground voltage at both ends of the secondary pressure plate at the same time, and intelligently judge whether it meets the conditions for the pressure plate to be put into use.

The above descriptions are preferred implementation modes of the present utility model, and are not intended to limit the present utility model in any form. It should be noted that, without departing from the spirit and essence of the present utility model, those skilled in the art can make various corresponding changes and deformations according to the present utility model, but these changes and deformations should all belong to this utility model. The scope of protection of the appended claims of the new model.

Claims (5)

1. a handheld digital secondary pressure plate measuring instrument, comprise hand-held housing (1), be installed on the test circuit in shell and display screen (11), it is characterized in that, this measuring instrument has three measurement test pencils, described test circuit comprises supply module, voltage measurement module and display module, supply module provides stabilized power source VCC, each module is all connected with single-chip microcomputer U, described voltage measurement module comprises two addition metering circuits, wherein two measurement test pencils and two addition metering circuits connect and are used for measuring mouth with secondary pressure plate and contact, an other measurement test pencil ground connection.

2. handheld digital secondary pressure plate measuring instrument according to claim 1, it is characterized in that, described addition metering circuit comprises the binding post connecting and measure test pencil, binding post is connected with the in-phase input end of operational amplifier one by voltage dependent resistor (VDR) R5 and multiple divider resistance, and the output terminal of this operational amplifier one is connected with single-chip microcomputer U input pin VTest by fast fuse wire F.

3. handheld digital secondary pressure plate measuring instrument according to claim 2, is characterized in that, described single-chip microcomputer U input pin VTest passes through two electric capacity C1 in parallel, electric capacity C2 ground connection; Described operational amplifier one is also connected with divider resistance R1, resistance R2, resistance R3 and resistance R4 in the same way between input end and binding post, the intermediate node of resistance R1 and resistance R2 by electric capacity C3 parallel with one another, have electrode capacitance C4 and resistance R4 ground connection, binding post is by voltage dependent resistor (VDR) R5 ground connection; Operational amplifier one reverse input end is connected with output terminal with resistance R7 ground connection respectively by resistance R6; This operational amplifier one in the same way input end is connected with operational amplifier two output terminal by resistance R8, and operational amplifier two in the same way input end connects adjustable voltage input circuit, and operational amplifier two reverse input end is connected with its output terminal.

4. handheld digital secondary pressure plate measuring instrument according to claim 3, it is characterized in that, adjustable voltage input circuit comprises the resistance R9, the resistance R10 that are series between power supply VCC and ground connection, and be connected to operational amplifier two in the same way between input end and resistance R9 resistance R10 at power supply VCC and an adjustable resistance R11, adjustable resistance R11 movable end of connecting between ground connection.

5. handheld digital secondary pressure plate measuring instrument according to claim 1, it is characterized in that, described supply module comprises the self-lock switch S0 being connected to accumulator the two poles of the earth and power supply VCC and holding, and power supply VCC has electrode capacitance C5, electric capacity C6 and voltage dependent resistor (VDR) R12 ground connection by parallel with one another.