CN102062823B - Electric leakage protection device tester - Google Patents

Abstract

The invention discloses a leakage protector tester, which comprises a casing, a liquid crystal display module on the casing, buttons on the casing, a test jack, a detection circuit in the casing, and a current output circuit. The two AC input ends of the rectifier bridge are connected to the two test sockets on the housing, the positive output end of the rectifier bridge is connected to two power resistors, and the other ends of the two power resistors are respectively connected to the collectors of the two Darlington tubes. The electrodes are connected, the bases of the two Darlington tubes are connected to the two current-limiting resistors, the other end of the two current-limiting resistors is connected to the output terminal of the D/A conversion chip, and the emitters of the two Darlington tubes are connected to the It is connected with a sampling resistor, and the other end of the sampling resistor is connected with the negative output terminal of the rectifier bridge. The invention can carry out current test and time test on the leakage protector, carry out voltage test on the external circuit, can give an alarm to the power supply undervoltage, and has complete functions such as automatic shutdown, and is widely used.

Description

A leakage protector tester

technical field

The invention relates to a leakage protector tester, in particular to an instrument for detecting whether the leakage protector is qualified. the

Background technique

At present, the leakage protector testers used in the market are relatively large in size, and the internal detection circuit is mostly an analog circuit, which is composed of discrete components, the circuit is complex, and the reliability is low. People can understand, and the operation is complicated, and the application area is narrow. the

Contents of the invention

Aiming at the above disadvantages, the present invention provides a leakage protector tester with reasonable structure, convenient use and multiple functions. the

The present invention is realized by following technology:

A leakage protector tester is mainly composed of a shell, a Chinese liquid crystal display on the shell, a power switch, a function selection setting key, a buzzer, a test jack, and a detection circuit in the shell. It is characterized in that: the Chinese liquid crystal is a 128*64 dot matrix liquid crystal, and the liquid crystal control line is connected with the single-chip microcomputer of the internal detection circuit. Both the power switch and the function selection setting key are thin-film keys, which are all connected with the single-chip microcomputer of the internal detection circuit. The buzzer is also connected with the microcontroller of the internal detection circuit. The internal detection circuit uses a single-chip microcomputer as the core component, and the current output circuit, leakage protector voltage measurement circuit, current measurement circuit, and power supply voltage measurement circuit are all connected to the A/D conversion chip, and the A/D conversion chip is connected to the single-chip computer. The current output circuit is connected with the current measurement circuit. The rectification circuit is connected with the current output circuit. The D/A conversion chip is connected with the single chip microcomputer, and connected with the current output circuit to control the current output of the current output circuit. The key detection circuit is connected with the single chip microcomputer and the external key. The buzzer circuit is connected with the microcontroller and the external buzzer. The single-chip microcomputer controls the D/A chip, and the D/A chip sends the signal to the current output circuit, and the current of the current output circuit is provided by the rectifier circuit, and the rectifier circuit is connected in series with the load terminal of the leakage protector. The current measurement circuit sends the signal measured from the circuit output circuit to the A/D conversion chip, and the A/D conversion chip sends the processed signal to the single-chip microcomputer, and the single-chip microcomputer sends the signal to the Chinese liquid crystal display. The single-chip microcomputer obtains the external key signal from the key detection circuit to execute the corresponding function. The single-chip microcomputer controls the buzzer stone to sound. The power supply voltage measurement circuit is connected with the battery of the instrument, and the signal is sent to the A/D conversion chip, and the A/D conversion chip sends the processing signal to the single-chip microcomputer. The leakage protector voltage measurement circuit is connected with the rectification circuit, and the measurement signal is sent to the A/D conversion chip, and the A/D conversion chip sends the processed signal to the single-chip microcomputer. the

The beneficial effects of the present invention are: 1. A large number of integrated components and digital circuits are used, so that the instrument circuit becomes very simple. 2. The device is small in size, accurate and safe in measurement, low in power consumption, rich in display content, easy to use and easy to carry. 3. It can carry out current test and time test on the leakage protector, carry out voltage test on the external circuit, it can alarm the power supply undervoltage, automatic shutdown and other functions are complete and widely used. the

Description of drawings

Fig. 1 is the circuit block diagram of the internal detection circuit diagram of this instrument;

Among them, 1. Liquid crystal display module 2, button scanning circuit 3, single-chip microcomputer circuit 4, D/A conversion circuit 5, current output circuit 6, current measurement circuit 7, voltage measurement circuit 8, power supply voltage measurement circuit 9, A/D conversion circuit

Figure 2 is a reference diagram for the connection of the button scanning circuit;

Among them, 10, current test selection key 11, time test selection key 12, test start key 13, gear key 14, LCD backlight key 15, on-off key

Figure 3 is a reference diagram for the connection of the current output circuit;

Figure 4 is a reference diagram for the connection of the D/A output circuit;

Figure 5 is a reference diagram for the connection of the single-chip power supply circuit;

Figure 6 is a reference diagram for the connection of the A/D conversion circuit;

Figure 7 is a reference diagram for connection of leakage protector voltage measurement circuit;

Figure 8 is an outline drawing of a leakage protector tester;

Among them, 16, liquid crystal display module 17, current test selection key 18, time test selection key 19, test start key 20, gear key 21, LCD backlight key 22, switch key 23, test port AC124, test port AC225, housing . the

Detailed ways

Figure 1 is a block diagram of the internal detection circuit of the tester. The liquid crystal display module 1 is connected with the single-chip microcomputer circuit 2, and the displayed content is controlled by the single-chip microcomputer. The key scanning circuit 1 is connected with the single-chip microcomputer circuit 2, and provides key-press signals for the single-chip microcomputer. The D/A conversion circuit 4 is connected with the single-chip microcomputer circuit 2 and controlled by the single-chip microcomputer, and the output is connected with the current output circuit 5 to control the current output of the current output circuit 5 . The current measurement circuit 6 is connected with the current output circuit 5 , and the collected current signal is sent to the A/D conversion circuit 9 . The voltage measurement circuit collects a voltage signal from the current output circuit 5 and sends it to the A/D conversion circuit 9 . The power measurement circuit 8 collects the instrument power signal and sends it to the A/D conversion circuit 9 for signal processing. The A/D conversion circuit 9 sends the processed signal to the single-chip microcomputer circuit 2 for further signal processing. the

Figure 2 is a reference diagram for the connection of the button scanning circuit. One end of the current test selection key 10 is grounded and the other end is connected to the resistor R1 and the capacitor C1, and the resistor R1 is connected to the other end of the capacitor C1. One end of the time test selection key 11 is connected to the ground and the other end is connected to the resistor R2 and the capacitor C2. The other end is connected, one end of the test start key 12 is connected to the ground and the other end is connected to the resistor R3 and the capacitor C3, the resistor R3 is connected to the other end of the capacitor C3, one end of the gear position key 13 is connected to the resistor R4 and the capacitor C4 is connected to the other end, the resistor R4 is connected to the capacitor The other end of C4 is connected, one end of LCD backlight key 14 is grounded and the other end is connected with resistor R5 and capacitor C5, the resistor R5 is connected with the other end of capacitor C5, one end of switch key 15 is grounded and the other end is connected with resistor R6 and capacitor C6, resistor R6 and The other end of the capacitor C6 is connected. Ports K1 , K2 , K3 , K4 , K5 , and K6 are respectively connected to the single-chip microcomputer of the single-chip microcomputer circuit 3 . the

Figure 3 is a reference diagram for the connection of the current output circuit. Port A is connected to the load terminal of the leakage protector. The rectifier bridge B1 is connected to port A to rectify the external power frequency alternating current. The output of rectifier bridge B1 is connected to two power resistors R9 and R10. The output terminals of resistors R9 and R10 are respectively connected to the two Darlington tubes Q1 and Q2 The collectors are connected, the emitters of Q1 and Q2 are connected with the sampling resistor R11, and the other end of the sampling resistor R11 is grounded. The bases of Q1 and Q2 are connected to resistors R7 and R8 respectively, and resistors R7 and R8 are connected. Port B is connected to port G of the D/A output circuit in FIG. 4 , and the current output of the current output circuit 5 is controlled by the voltage output of the D/A output circuit. Port C is connected to port I2 of the A/D conversion circuit in FIG. 6 . the

Figure 4 is a reference diagram for the connection of the D/A output circuit. The fifth pin of the D/A conversion chip IC1 is connected to the voltage reference chip W1, the R end of W1 is connected to the resistor R12, and the other end of R12 is grounded. The G terminal of IC1 is connected to the B terminal in the connection reference diagram of the current output circuit in Fig. 3 to control the current output of the current output circuit. The D, E, F terminals of IC1 are connected with the single-chip microcomputer port of the single-chip circuit 3 and are controlled by the single-chip microcomputer. the

Figure 5 is a reference diagram for the connection of the single-chip power supply circuit. The power supply of the instrument is input through port H3. The emitter set of the transistor Q3 is connected to the base through a feedback resistor R15. The emitter of Q3 is connected to the positive pole of the power supply, the collector of Q3 is connected to the three-terminal voltage regulator chip Q5, the output terminal 3 of Q5 provides power for the single-chip circuit, the A/D conversion circuit 9 and the D/A conversion circuit 4, and the base of Q3 The electrode is connected to the diode and the resistor R16, and R16 is connected to the collector of the triode Q4, and the base and the emitter of Q4 are connected through the feedback resistor R19, and the emitter of Q4 is connected to the ground. The other end of the diode D1 is connected to the resistor R17, and R17 is connected to the diode D2. The port H4 is connected to the switch key 15 , and the ports H1 and H2 are respectively connected to the single-chip microcomputer of the single-chip circuit 3 . When the switch key 15 is pressed, the port H4 is set low, and the triode Q3 is turned on to output VCC at the terminal 3 of the three-terminal voltage regulator chip, so that the port H2 is set high, so that the triode Q4 is turned on. At this time, even if the switch key 15 is released open, the transistor Q3 is still conducting to realize the power-on function. When the switch key 15 is pressed again, the H4 port is set low, so that the port H1 is low, and the single-chip microcomputer in the single-chip circuit 3 detects the port H1, and the port H2 is set low, so that the transistor Q4 is cut off, so that the transistor Q3 is cut off, Make the collector output of the transistor Q3 low, so as to realize the shutdown function. The voltage dividing resistor R14 is connected to the emitter of the triode Q3, the voltage dividing resistor R13 is connected to R14, and the other end of the voltage dividing resistor R14 is connected to the ground. Port H is connected to port I4 of the A/D conversion circuit connection reference diagram in FIG. 6 , and provides a power supply voltage signal for the A/D conversion circuit 9 . the

Figure 6 is a reference diagram for the connection of the A/D conversion circuit. Pins 1, 2, and 3 of the A/D conversion chip IC2 are connected to resistors R20, R21, and R22 respectively, and pins 1 and 2 of IC2 are connected to protection diodes D3 and D4. The port I1 is connected with the single-chip microcomputer of the single-chip microcomputer circuit 3, so that the conversion signal of the A/D conversion chip can be read into the single-chip microcomputer. the

Fig. 7 is a reference diagram for connection of the leakage protector voltage measurement circuit. The voltage dividing resistor R24 is connected to pin 2 of the rectifier bridge B1 in the current output circuit connection reference diagram in FIG. 3 , the voltage dividing resistor R23 is connected to R24, and the other end is connected to the ground. Port G2 is connected to I3 in the A/D conversion circuit connection reference diagram in Figure 6. Divide the voltage through the voltage dividing resistors R23 and R24, collect the rectified voltage signal to the A/D conversion circuit in Figure 6 and connect it to IC2 in the reference figure for analog-to-digital conversion. the

Instructions:

1. For current test, insert the two test leads into the test port AC123 and test port AC224 respectively, press the shift key 13 to select the measurement gear, press the current test select key 11 to select the test mode of the leakage protector, and press the test start key 12 Carry out the test, and display the breaking current on the LCD screen after the leakage protector is broken. the

2. Time test, insert the test leads into the test port AC123 and test port AC224 respectively, press the shift key 13 to select the measurement gear, press the time test select key 12 to select the test mode of the leakage protector, press the test start key 12 Carry out the test, after the leakage protector is broken, the current at the time of breaking and the time from the beginning of energization to the time of breaking are displayed on the LCD screen. the

3. Press the LCD backlight key 14 to control the LCD backlight, and the automatic shutdown of the instrument can be realized through the reference diagram of the single-chip power supply circuit connection in Figure 5. the

Claims (1)

1. tester for leakage protector; comprise housing; LCD MODULE on the housing; button on the housing; test jack; and the testing circuit in the housing; it is characterized in that: two ac input ends of rectifier bridge link to each other with two test jack on the housing; the positive output end of rectifier bridge links to each other with two power resistors; the other end of two power resistors links to each other with the collector of two Darlington transistors; the base stage of two Darlington transistors links to each other with two current-limiting resistances respectively; the other end of two current-limiting resistances links to each other with the output terminal of D/A conversion chip; the emitter of two Darlington transistors links to each other with same sampling resistor, the other end ground connection of sampling resistor.

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