The bureau puts the examination ultrasonic sensor circuit design

Ultrasonic Sensor Circuit Design for Partial Discharge Detection

Partial discharge detection is an important method for maintaining the safe and stable operation of electrical power systems. In high-voltage equipment, partial discharge can be an early sign of insulation defects, aging materials, surface contamination or hidden electrical faults. Detecting these signals early helps engineers reduce failure risk and improve power system reliability.

Common partial discharge detection methods include electromagnetic detection and ultrasonic detection. Each method has its own advantages. Electromagnetic methods can detect electrical signals generated by discharge activity, while ultrasonic detection focuses on the acoustic energy produced when partial discharge occurs inside or around electrical equipment.

For ultrasonic partial discharge detection, sensor sensitivity is one of the most important performance factors. If the ultrasonic sensor circuit has low sensitivity or high noise, weak discharge signals may be difficult to identify. To improve detection performance, a low noise amplifier, also known as an LNA, and logarithmic detection technology can be used in the circuit design.

Why Partial Discharge Detection Matters

Partial discharge does not always cause immediate equipment failure, but it can gradually damage insulation materials. Over time, this may lead to breakdown, unplanned shutdowns, expensive maintenance and safety risks. For switchgear, transformers, cables and other high-voltage equipment, regular partial discharge inspection is an important part of preventive maintenance.

A sensitive detection system helps maintenance teams find abnormal discharge activity before it develops into a serious fault. This is why ultrasonic sensors and related signal processing circuits are widely studied and used in power equipment inspection.

Ultrasonic Detection and Electromagnetic Detection

Electromagnetic detection and ultrasonic detection are two useful approaches for partial discharge testing. Electromagnetic methods detect electrical or radio-frequency signals caused by discharge activity. Ultrasonic methods detect the sound waves generated by the rapid energy release of partial discharge.

Key Challenge: Low Ultrasonic Sensor Sensitivity

One challenge in ultrasonic partial discharge detection is that the discharge signal can be very weak. The signal may be affected by distance, equipment structure, background noise and the sensitivity of the ultrasonic sensor itself. If the front-end circuit cannot amplify the useful signal clearly, the detection result may be unstable.

To solve this problem, the ultrasonic sensor circuit should be designed with low-noise signal amplification and effective signal detection. A high-sensitivity circuit can improve the ability to capture weak ultrasonic signals generated by partial discharge.

Using LNA in Ultrasonic Sensor Circuit Design

A low noise amplifier is used to amplify weak ultrasonic signals while keeping circuit noise as low as possible. In a partial discharge ultrasonic sensor, the LNA is usually placed near the sensor front end so that the useful signal can be strengthened before further processing.

The LNA design should consider gain, bandwidth, input impedance, noise level and power consumption. For portable or battery-powered inspection devices, low power consumption is also important because the sensor may need to operate for long inspection periods in the field.

Logarithmic Detection for Wider Signal Measurement

Logarithmic detection technology can help process ultrasonic signals with a wide dynamic range. In partial discharge testing, signal strength may vary greatly depending on the discharge intensity, location and surrounding structure. A logarithmic detector can compress this wide signal range and make it easier for the system to measure and compare signal levels.

By combining a low noise amplifier with logarithmic detection, the ultrasonic sensor circuit can improve sensitivity, increase measurement stability and support more practical field inspection applications.

Basic Signal Chain of the Ultrasonic Sensor Circuit

A typical ultrasonic partial discharge sensor circuit includes an ultrasonic sensing element, low noise amplifier, filter circuit, logarithmic detector, output processing circuit and power supply module. The goal is to capture weak acoustic signals, reduce noise and provide a stable output for analysis.

Performance Testing: Sensitivity and Gain

After the ultrasonic sensor circuit is designed, performance testing is required. Key test items include sensitivity, gain, noise level, detection stability and power consumption. These results help determine whether the sensor can detect weak partial discharge signals in practical inspection conditions.

A high-sensitivity ultrasonic sensor with suitable gain can improve the reliability of partial discharge detection. When the circuit is powered by battery, it can also be used more conveniently for portable inspection of power equipment.

Applications in Power Equipment Maintenance

Ultrasonic partial discharge sensors can be used in the inspection of switchgear, transformers, cable accessories and other electrical equipment. They are especially useful when maintenance teams need a non-invasive detection method for identifying possible insulation problems.

For power system maintenance, combining ultrasonic detection with other partial discharge testing methods can provide a more complete understanding of equipment condition. This helps improve fault diagnosis and supports condition-based maintenance.

FAQ About Ultrasonic Partial Discharge Detection

What is partial discharge detection?

Partial discharge detection is a method used to identify small electrical discharges inside or around insulation systems. It helps find early insulation defects in high-voltage electrical equipment.

Why use ultrasonic sensors for partial discharge detection?

Ultrasonic sensors can detect acoustic waves produced by discharge activity. They are useful for non-invasive inspection and can help locate discharge sources in electrical equipment.

What does an LNA do in an ultrasonic sensor circuit?

An LNA, or low noise amplifier, amplifies weak ultrasonic signals while adding as little noise as possible. This improves the sensitivity of the detection circuit.

Why is logarithmic detection used in partial discharge sensors?

Logarithmic detection helps process signals with a wide dynamic range. It makes it easier to measure and compare ultrasonic signal strength from different discharge levels.

Can ultrasonic partial discharge sensors be battery powered?

Yes. A well-designed ultrasonic sensor circuit can use battery power, which is useful for portable inspection tools and field maintenance applications.

What equipment can be tested with ultrasonic partial discharge detection?

Ultrasonic partial discharge detection can be used for switchgear, transformers, cable accessories and other high-voltage electrical equipment where insulation condition needs to be monitored.