Non-disconnection CT secondary circuit inspection tester

Abstract

The utility model discloses an unbroken CT secondary circuit inspection tester which comprises a shell, a liquid crystal display screen and a soft keyboard are arranged on the shell, a current output port, a current acquisition port and a voltage acquisition port are arranged above the shell, and a control mechanism and a lithium battery are arranged in the shell. An output end of the lithium battery is connected with a power input end of the control mechanism, output ends of the soft keyboard, the current acquisition port and the voltage acquisition port are respectively connected with an input end of the control mechanism, an output end of the control mechanism is respectively connected with input ends of the liquid crystal display screen and the current output interface, and the current output port is connected to a load side through the current clamp. The current acquisition port and the voltage acquisition port are respectively connected with a CT secondary side terminal; a power switch is arranged at the lower end of the shell. According to the utility model, the impedance measurement of the secondary circuit can be completed without disconnection of the CT secondary circuit, the impedance measurement is not influenced by the inductance of the CT secondary side winding, the measurement is faster, more accurate and safer, and the measurement efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of CT secondary circuit testing, and more particularly to a non-untwisting CT secondary circuit inspection instrument. Background Art

[0002] The traditional method for measuring the DC resistance of a CT's secondary circuit is to disconnect the CT's secondary load-side wiring, then use a multimeter to measure the secondary circuit's DC resistance to check whether each phase's resistance value is within the normal range. This method presents several issues during testing: 1) Due to the large resistance measurement error of the multimeter, which can sometimes exceed 1 ohm, this method can easily misjudge the circuit's integrity; 2) The CT and secondary circuits must be disconnected during the measurement process, increasing the tester's workload; 3) Forgetting to restore the secondary circuit wiring during testing can result in a CT secondary open circuit fault, endangering system safety; 4) If screws are not tightened or become stripped during the secondary circuit restoration process, this can increase the risk of failure. Utility Model Content

[0003] The technical problem to be solved by the utility model is to provide a non-untwisting CT secondary circuit inspection instrument, which does not require wiring during the measurement process, and the measurement process is safe and accurate, improves measurement efficiency, and reduces safety hazards.

[0004] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows.

[0005] The un-untangled CT secondary circuit tester includes a shell, which is provided with a liquid crystal display for displaying test results and a soft keyboard for setting test parameters. A current output port for outputting high-frequency alternating current and a current acquisition port and a voltage acquisition port for acquiring the CT secondary side port current and port voltage are provided above the shell. A control mechanism for controlling the test of the CT secondary circuit and a lithium battery for storing electrical energy are provided inside the shell. The output end of the lithium battery is connected to the power input end of the control mechanism, the output ends of the soft keyboard, the current acquisition port and the voltage acquisition port are respectively connected to the input end of the control mechanism, the output end of the control mechanism is respectively connected to the input end of the liquid crystal display and the current output interface, the current output port is connected to the load side through a current clamp, and the current acquisition port and the voltage acquisition port are respectively connected to the CT secondary side terminal; a power switch for controlling the power on and off of the tester is provided at the lower end of the shell, and the output end of the power switch is connected to the input end of the control mechanism.

[0006] To further optimize the technical solution, the control mechanism includes a 16-bit DAC digital-to-analog converter for outputting a high-frequency AC low-voltage signal, a current power amplifier for amplifying the AC low-voltage signal, a conditioning circuit for conditioning the collected voltage and current signals, a 16-bit ADC for performing analog-to-digital conversion on the collected signals, and a CPU for controlling the CT secondary circuit test. The output end of the CPU is connected to the input end of the 16-bit DAC digital-to-analog converter, the output end of the 16-bit DAC digital-to-analog converter is connected to the input end of the current power amplifier, the output end of the current power amplifier is connected to the current output port, the current acquisition port and the voltage acquisition port are respectively connected to the input end of the signal conditioning circuit, the output end of the signal conditioning circuit is connected to the input end of the 16-bit ADC, and the output end of the 16-bit ADC is connected to the input end of the CPU.

[0007] To further optimize the technical solution, the control mechanism further includes a serial FLASH for storing test parameters and correction coefficients, and the serial FLASH is electrically connected to the CPU.

[0008] To further optimize the technical solution, the control mechanism also includes a Wifi chip for connecting to a wireless network, and the Wifi chip is electrically connected to the CPU.

[0009] To further optimize the technical solution, the control mechanism also includes a battery power detection circuit for detecting the battery power, the input end of the battery power detection circuit is connected to the output end of the lithium battery, and the output end of the battery power detection circuit is connected to the input end of the CPU.

[0010] To further optimize the technical solution, a charging port for charging the lithium battery is provided at the lower end of the shell, and the charging port is connected to the input end of the lithium battery.

[0011] Further optimizing the technical solution, the LCD screen is a touchable LCD screen.

[0012] Due to the adoption of the above technical solution, the technical progress achieved by the present invention is as follows.

[0013] The utility model provides a CT secondary circuit tester without unwinding the wires, which can complete the secondary circuit impedance measurement of the CT secondary circuit without unwinding the wires. It is not affected by the inductance of the CT secondary side winding, which changes the traditional secondary circuit measurement method. The measurement is faster, more accurate and safer, and potential problems caused by the secondary circuit recovery process are avoided during measurement, thereby improving the measurement efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural diagram of the utility model;

[0015] Figure 2 This is a structural block diagram of the control mechanism of the utility model;

[0016] Figure 3 This is the circuit diagram of the 16-bit DAC digital-to-analog converter of the utility model;

[0017] Figure 4 This is a circuit diagram of the current power amplifier of the utility model;

[0018] Figure 5 This is a circuit diagram of the signal conditioning circuit of the utility model;

[0019] Figure 6 16 is a circuit diagram of ADC of the present utility model;

[0020] Figure 7 This is a circuit diagram of the CPU of the utility model;

[0021] Figure 8 This is the circuit diagram of the serial FLASH of the utility model;

[0022] Figure 9 This is the circuit diagram of the Wifi chip of the utility model;

[0023] Figure 10 This is the circuit diagram of the battery capacity detection module of the utility model;

[0024] Figure 11 This is a test wiring diagram of the present utility model.

[0025] Among them: 1. Housing, 2. LCD screen, 3. Soft keyboard, 4. Current output port, 5. Current acquisition port, 6. Voltage acquisition port, 7. Charging port, 8. Power switch. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Uninterrupted CT secondary circuit tester, combined with Figure 1 As shown, it includes a housing 1, on which a liquid crystal display 2 and a soft keyboard 3 are provided. The liquid crystal display 2 is a touchable liquid crystal display for displaying test results, and the soft keyboard 3 is used to set test parameters.

[0028] A current output port 4, a current acquisition port 5 and a voltage acquisition port 6 are provided above the shell 1. The current output port 4 is used to output high-frequency alternating current. The current acquisition port 5 and the voltage acquisition port 6 are used to acquire the CT secondary side port current and port voltage. A control mechanism and a lithium battery are provided in the shell 1. The control mechanism is used to control the test of the CT secondary circuit. The lithium battery is used to store electrical energy. The output end of the lithium battery is connected to the power input end of the control mechanism. The output ends of the soft keyboard, the current acquisition port and the voltage acquisition port are respectively connected to the input end of the control mechanism. The output end of the control mechanism is respectively connected to the input end of the liquid crystal display and the current output interface. The current output port 4 is connected to the load side through a current clamp. The current acquisition port 5 and the voltage acquisition port 6 are respectively connected to the CT secondary side terminal.

[0029] The lower end of the housing 1 is provided with a charging port 7 and a power switch 8. The charging port 7 is used to charge the lithium battery and is connected to the input terminal of the lithium battery. The power switch 8 is used to control the power on and off of the tester. The output terminal of the power switch is connected to the input terminal of the control mechanism.

[0030] The structural diagram of the control mechanism is as follows Figure 2 As shown, it includes a 16-bit DAC digital-to-analog converter, a current power amplifier, a conditioning circuit, a 16-bit ADC and a CPU. The output end of the CPU is connected to the input end of the 16-bit DAC digital-to-analog converter, the output end of the 16-bit DAC digital-to-analog converter is connected to the input end of the current power amplifier, the output end of the current power amplifier is connected to the current output port 4, the current acquisition port 5 and the voltage acquisition port 6 are respectively connected to the input end of the signal conditioning circuit, the output end of the signal conditioning circuit is connected to the input end of the 16-bit ADC, and the output end of the 16-bit ADC is connected to the input end of the CPU.

[0031] The 16-bit DAC digital-to-analog converter is used to output high-frequency AC low-voltage signals. The circuit diagram of the 16-bit DAC digital-to-analog converter is as follows: Figure 3 As shown, a small AC voltage signal is provided to the current power amplifier.

[0032] The current power amplifier is used to amplify the driving signal provided by the 16-bit DAC digital-to-analog converter and output high-frequency AC current. The circuit diagram of the current power amplifier is shown in the figure. Figure 4 shown.

[0033] The conditioning circuit is used to condition the collected voltage and current signals into proportional AC small voltage signals. The CPU controls the 16-bit ADC to collect the conditioned signals. The circuit diagrams of the conditioning circuit, 16-bit ADC and CPU are shown in the following figure. Figure 5 、 Figure 6 and Figure 7 shown.

[0034] The current signal collected by the current output port 4 is converted into a proportional AC small current signal after conditioning by the conditioning circuit, and the current signal is collected by the 16-bit ADC, which is recorded as Ia. The voltage signal collected by the voltage output port 5 is converted into a proportional AC small voltage signal after conditioning by the conditioning circuit, and the voltage signal is collected by the 16-bit ADC, which is recorded as Ua. The loop impedance R = Ua / Ia, and the DC resistance of the CT secondary circuit is measured by high-frequency AC.

[0035] Theoretically, the CT secondary winding will shunt the AC current output by the tester. However, since the inductive reactance of the CT secondary winding is much larger than the loop resistance, the shunt of the test current output by the instrument is very small, and most of the test current output by the instrument flows through the secondary circuit.

[0036] The loop impedance is resistive, and the capacitance and inductance components can be ignored. Therefore, the measured AC impedance value and DC impedance value are almost the same, with a very small error.

[0037] The control mechanism also includes a serial FLASH, a Wifi chip and a battery power detection circuit. The serial FLASH and Wifi are electrically connected to the CPU respectively. The input end of the battery power detection circuit is connected to the output end of the lithium battery, and the output end of the battery circuit detection circuit is connected to the input end of the CPU.

[0038] The serial FLASH is used to store test parameters and correction coefficients. The Wifi chip is used to connect to the network and implement software upgrades. The battery power detection module is used to detect the battery power. The circuit diagrams of the serial FLASH, Wifi chip and battery power detection circuit are shown below. Figure 8 、 Figure 9 and Figure 10 shown.

[0039] The test wiring diagram of the utility model is as follows Figure 11 As shown, the current acquisition port and voltage acquisition port of the tester are connected to the secondary side terminals of the CT, and the current output port is connected to the load side through the current clamp. The current clamp outputs high-frequency AC current to the load side. The tester measures the port voltage value and the current value of the current clamp, calculates the AC impedance value of the load, and displays it on the LCD screen.

Claims

1. Non-untwisting CT secondary circuit tester, characterized by: The invention comprises a housing (1), a liquid crystal display (2) for displaying test results and a soft keyboard (3) for setting test parameters are provided on the housing (1), a current output port (4) for outputting high-frequency alternating current, and a current acquisition port (5) and a voltage acquisition port (6) for acquiring CT secondary side port current and port voltage are provided above the housing (1), a control mechanism for controlling the test of the CT secondary circuit and a lithium battery for storing electric energy are provided inside the housing (1), the output end of the lithium battery is connected to the power input end of the control mechanism, the output ends of the soft keyboard, the current acquisition port and the voltage acquisition port are respectively connected to the input end of the control mechanism, the output end of the control mechanism is respectively connected to the input end of the liquid crystal display and the current output interface, the current output port (4) is connected to the load side through a current clamp, and the current acquisition port (5) and the voltage acquisition port (6) are respectively connected to the CT secondary side terminal; a power switch (8) for controlling the on / off of the tester is provided at the lower end of the housing (1), and the output end of the power switch is connected to the input end of the control mechanism.

2. The non-untieable CT secondary circuit inspection instrument according to claim 1, characterized in that: The control mechanism comprises a 16-bit DAC digital-to-analog converter for outputting a high-frequency AC low-voltage signal, a current power amplifier for amplifying the AC low-voltage signal, a conditioning circuit for conditioning the collected voltage and current signals, a 16-bit ADC for performing analog-to-digital conversion on the collected signals, and a CPU for controlling the CT secondary circuit test. The output end of the CPU is connected to the input end of the 16-bit DAC digital-to-analog converter, the output end of the 16-bit DAC digital-to-analog converter is connected to the input end of the current power amplifier, the output end of the current power amplifier is connected to the current output port (4), the current acquisition port (5) and the voltage acquisition port (6) are respectively connected to the input end of the signal conditioning circuit, the output end of the signal conditioning circuit is connected to the input end of the 16-bit ADC, and the output end of the 16-bit ADC is connected to the input end of the CPU.

3. The non-untwisting CT secondary circuit inspection instrument according to claim 2, characterized in that: The control mechanism further comprises a serial FLASH for storing test parameters and correction coefficients, and the serial FLASH is electrically connected to the CPU.

4. The non-untwisting CT secondary circuit inspection instrument according to claim 2, characterized in that: The control mechanism also includes a Wifi chip for connecting to a wireless network, and the Wifi chip is electrically connected to the CPU.

5. The non-untieable CT secondary circuit inspection instrument according to claim 2, characterized in that: The control mechanism further includes a battery power detection circuit for detecting the battery power. The input end of the battery power detection circuit is connected to the output end of the lithium battery, and the output end of the battery power detection circuit is connected to the input end of the CPU.

6. The non-untieable CT secondary circuit inspection instrument according to claim 1, characterized in that: The lower end of the housing (1) is provided with a charging port (7) for charging the lithium battery, and the charging port is connected to the input end of the lithium battery.

7. The non-untwisting CT secondary circuit inspection instrument according to claim 1, characterized in that: The liquid crystal display screen (2) is a touchable liquid crystal display screen.

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