What are the monitoring devices for oil-immersed transformers

Electrical parameter monitoring devices

• Voltage and current monitoring devices: The voltage and current signals of the transformer are collected through the voltage transformer (PT) and current transformer (CT) to monitor the operating status of the transformer in real time and ensure that it works within the rated range.
• Power factor monitoring devices: By measuring the phase difference between voltage and current, the power factor is calculated, reflecting the nature of the transformer's load and operating efficiency.
• Harmonic monitoring devices: Monitor the quality of transformer power supply, including current/voltage harmonic distortion rate, 2nd~50th harmonic content, etc., to determine whether harmonic pollution exists.

Temperature monitoring devices

• Winding temperature monitoring device: Thermistors or fiber optic sensors, etc. are used to measure the temperature of the transformer windings directly or indirectly to prevent the windings from being damaged due to overheating.
• Oil temperature monitoring device: The temperature of the transformer oil is monitored in real time by temperature sensors installed in the transformer tank to ensure that it is within safe limits.

Partial discharge monitoring device

• Ultra High Frequency (UHF) Sensors: The monitoring frequency band is 300MHz-3000MHz, with high sensitivity, it can detect weak localized discharge signals and is suitable for early detection of insulation defects.
• High Frequency Current (HFCT) Sensors: Installed on transformer grounding conductors or cable shielding armor, it detects high-frequency pulse currents and finds precursors of insulation deterioration.
• Ultrasonic (AE) sensors: Localization and quantitative analysis of partial discharges is achieved by detecting ultrasonic signals excited by partial discharges inside the transformer.

Dissolved gas in oil monitoring device

• Through techniques such as gas chromatography or photoacoustic spectroscopy, we analyze the composition of dissolved gases in transformer oil (e.g., hydrogen, methane, acetylene, etc.) to determine whether there are faults such as overheating and discharge within the transformer.

Vibration monitoring devices

• The vibration sensor is used to collect the vibration signal of the transformer, and through modal analysis and other methods, to determine whether the internal structure of the transformer has changed, so as to realize early fault diagnosis.

Environmental monitoring devices

• Temperature and humidity sensors: Installed around the transformer, it monitors the ambient temperature and humidity to prevent any degradation of the transformer's insulation due to harsh environmental conditions.