Overview
The APD300-L is a triple-in-one wired partial discharge sensor specifically designed for medium-voltage switchgear. It integrates Acoustic Emission (AE), Transient Earth Voltage (TEV), and Ultra-High Frequency (UHF) detection technologies to continuously monitor partial discharge activity inside the cable compartment.
The sensor is mounted via strong magnetic adsorption—no drilling or power outage required. It outputs discharge amplitude, frequency, and environmental parameters (noise, temperature, humidity) via RS485 wired communication, with independently configurable alarm thresholds.
Its wide operating temperature range and compact design make it suitable for harsh industrial environments, providing reliable insulation status warnings for power systems.
Highlight
Multi-Technology Integration
- AE/TEV/UHF in one device
- Monitors amplitude & frequency
- Environmental compensation (noise/temp/humidity)
High Precision & Fast Response
- Wide measurement range
- 4s rapid sampling cycle
- High-sensitivity sensors
Flexible Alarm & Configuration
- Independent threshold setting
- Trigger on >25 discharge counts
- RS485 Modbus-RTU interface
Robust & Easy Installation
- Strong magnetic mount
- Wide temp -40~85℃ operation
- Compact 135×100×42mm size
Function
| AE Monitoring | Measures ultrasonic signals from partial discharges. Range: 0～60 dBμV, resonant frequency 40kHz±1kHz. Provides discharge count, amplitude, average value, and alarm status. |
| TEV Monitoring | Detects transient earth voltage signals. Range: 0～60 dBmV, bandwidth 3MHz～100MHz. Outputs discharge count, amplitude, environmental baseline, and alarm. |
| UHF Monitoring | Captures ultra-high frequency electromagnetic waves. Range: -70～+10 dBm, bandwidth 300MHz～1500MHz. Reports discharge count, amplitude, average value, and alarm |
| Environmental Monitoring | Integrated noise (30～130dB), temperature (-40～85℃), and humidity (0～100%RH) sensors for comprehensive condition assessment. |
| Alarm Logic | Alarm triggered when amplitude exceeds preset threshold and discharge count >25. Three independent alarms: AE, TEV, UHF. |
| RS485 Communication | Modbus-RTU protocol, baud rate 9600 (default). Reads real-time data and writes alarm thresholds. |
| Configurable Parameters | Communication address, baud rate, AE/TEV/UHF alarm thresholds can be set via Modbus. |
| Real-Time Data Output | Continuous sampling every 4 seconds; data includes discharge counts, amplitudes, averages, and alarm flags for all three channels, plus environmental values |
Specification
| Parameter | Value |
| Power Supply | DC 12～36 V |
| Communication | RS485, Modbus-RTU, baud rate 9600 (default) |
| Sampling Cycle | 4 s |
| AE Sensor | |
| – Measuring Range | 0～60 dBμV |
| – Resonant Frequency | 40 kHz ±1 kHz |
| TEV Sensor | |
| – Measuring Range | 0～60 dBmV |
| – Bandwidth | 3 MHz ～ 100 MHz |
| UHF Sensor | |
| – Measuring Range | -70 ～ +10 dBm |
| – Frequency Band | 300 MHz ～ 1500 MHz |
| – Average Equivalent Height | ≥10 mm |
| Environment Sensors | |
| – Noise Level | 30 ～ 130 dB |
| – Temperature | -40 ～ 85 ℃ |
| – Humidity | 0 ～ 100 % RH |
| Operating Temperature | -40 ～ 85 ℃ |
| Relative Humidity | ≤95 % RH |
| Dimensions (W×H×D) | 135 mm × 100 mm × 42 mm |
| Mounting | Magnetic adsorption |
| Protection Grade | IP65 (sensor head) |
| Weight | Approx. 0.5 kg |
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FAQ
The APD300-L features strong magnetic adsorption, allowing it to be mounted directly on the inner wall or door of the switchgear cable compartment without drilling or power outage—just place and it works.
It supports RS485 interface with standard Modbus-RTU protocol, default baud rate 9600, for easy integration into existing monitoring systems.
Alarm thresholds for AE, TEV, and UHF can be set independently via Modbus communication (e.g., AE default 30 dBμV, TEV default 30 dBmV, UHF default -30 dBm). When the amplitude exceeds the threshold and the discharge count exceeds 25, the corresponding alarm flag is set.
Yes. APD300-L operates at -40℃ to +85℃, humidity ≤95% RH, and the sensor head is IP65-rated, making it suitable for outdoor or industrial applications.
By reading registers 0000H～000EH via RS485 bus using Modbus-RTU protocol, you can obtain discharge counts, amplitudes, averages, alarm status for AE/TEV/UHF, as well as environmental data (noise, temperature, humidity).
Summary
The APD300-L is a comprehensive wired partial discharge monitoring solution for medium-voltage switchgear, integrating AE, TEV, and UHF sensors into a single compact device. Its strong magnetic mounting enables tool-free installation without power outage, while the IP65-rated sensor head ensures reliable operation in harsh industrial environments. With a 4-second sampling cycle, independent alarm thresholds (triggered when amplitude exceeds preset value and discharge count >25), and full environmental monitoring (noise, temperature, humidity), the APD300-L provides early warning of insulation degradation. Data is transmitted via RS485 with Modbus-RTU protocol, allowing seamless integration into existing SCADA or condition monitoring systems. Designed for wide temperature range (-40°C to +85°C) and high humidity (≤95% RH), this sensor helps prevent unplanned downtime and extends equipment life, making it an ideal choice for utilities, industrial plants, and renewable energy applications requiring reliable partial discharge detection.
