The transformer partial discharge tester is a specialized instrument used to detect partial discharge phenomena in transformers



(including current transformers and voltage transformers). This tester helps evaluate the insulation condition of transformers, thereby preventing potential faults. Below is an overview article about the transformer partial discharge tester.



Transformer Partial Discharge Tester



Overview



The transformer partial discharge tester is a professional device used to detect partial discharge phenomena in transformers. By capturing and analyzing signals such as electromagnetic waves, acoustic waves, or electrical pulses generated by partial discharges, it evaluates the insulation condition of the transformer. This detection is crucial for predicting and preventing potential faults in transformers.



Working Principle



The working principle of the transformer partial discharge tester is based on detecting and analyzing signals generated by partial discharges. When partial discharge occurs under the test voltage, the tester detects high-frequency pulse currents through the system coupling capacitor. These pulse current signals are sent to the input data unit of the tester for processing. The specific process is as follows:




  1. Signal Capture: Capture the pulse current generated by partial discharge through the coupling capacitor Ck.

  2. Signal Amplification: The pulse signal is initially amplified by a low-noise preamplifier.

  3. Filtering and Selection: Select the desired frequency range through a filter amplifier to remove interference signals.

  4. Signal Processing: After further amplification by the main amplifier, the signal is sent to the pulse peak unit for processing to display the peak value of the pulse.

  5. Result Display: Display the discharge pulses and related data such as discharge quantity and frequency through an oscilloscope or other display devices.



Key Components




  • Coupling Capacitor: Captures the pulse current generated by partial discharge.

  • Preamplifier: Initially amplifies weak pulse signals.

  • Filter: Selects signals within a specific frequency range to eliminate interference.

  • Main Amplifier: Further amplifies the signal to a detectable level.

  • Display Unit: Displays the graphical and numerical information of discharge pulses.



Technical Specifications




  • Capacitance Range of Test Object: Typically supports a capacitance range from a few picofarads to several thousand picofarads.

  • Detection Sensitivity: Varies depending on the model and brand.

  • Elliptical Scanning Time Base:

    • Frequency: 50, 100, 150, 200, 400 Hz.

    • Rotation: Adjustable in 30-degree steps, up to 120 degrees.

    • Operating Mode: Standard - Expanded - Linear.

    • Input Voltage Range for High-Frequency Time Base Ellipse: 13~275V.



  • Display Unit: Uses a 100×80mm rectangular oscilloscope tube with brightness and focus adjustment knobs.



Usage Method




  1. Startup Preparation: Ground the instrument properly, connect the power supply, and set the display mode to "Ellipse" mode.

  2. Calibration: Use the calibration pulse generator to calibrate before applying the test voltage.

  3. Adjust Amplifier: Adjust the amplifier gain knob so that the injected pulse height is moderate, ensuring it matches the known injected charge.

  4. Disconnect Calibration Connection: Remove the connection between the calibration pulse generator and the test circuit.

  5. Test Operation: Connect the high-voltage test circuit power supply, slowly increase the test voltage, and note the first occurrence of continuous discharge.