Frequently Asked Questions about Online Transformer Temperature MonitoringFAQ

• Covering everything from selection to operations and maintenance: This article summarizes the most common issues in online transformer temperature monitoring, ranging from thermostat selection and sensor configuration to routine inspections and data analysis.

1. Product Selection and Configuration

1.1 Q:Dry-type transformer thermostatWhat should you pay the most attention to when selecting a model?

A: The most important factor is ensuring that the function suffix matches your requirements. The suffixes D, E, F, G, and I correspond to display, alarm, fan control, communication, and current monitoring, respectively. When selecting a model, verify exactly which functions are needed to avoid omissions or selecting unnecessary features.

1.2 Q: How many temperature controllers are required for an oil-filled transformer?

Answer: At least one oil-level thermostat is required (BWY(series). For critical main transformers, it is recommended to install a winding temperature controller (BWR(series), the two thermostats protect the transformer from different angles.

1.3 Q: Should I opt for fiber optic temperature measurement?

A: Fiber-optic sensors are recommended for substations with complex electromagnetic environments, applications requiring exceptionally high temperature measurement accuracy, situations where multi-point temperature measurement along the windings is necessary, or when transformers operate under extreme temperature conditions. For standard applications, the PT100 solution is sufficient.

2. Installation and Usage

2.1 Q: Are there any requirements regarding the installation location of the thermostat?

Answer: It should be installed in a location that is easily visible to inspection personnel. Temperature controllers for dry-type transformers are typically embedded in the transformer’s outer casing. For oil-filled transformers, the temperature controller dial is mounted on a dedicated bracket on the side of the oil tank, and the capillary tube route should avoid sharp bends and mechanical compression.

2.2 Q: Do PT100 sensors need to be replaced periodically?

A: PT100 sensors are designed for a long service life and generally do not require regular replacement. However, they should be calibrated annually to verify their accuracy. If calibration reveals zero-point drift or a decrease in sensitivity beyond the permissible range, the sensor must be replaced.

2.3 Q:Cooling FansHow do I connect the control wires?

Answer: Connect the fan power supply to the fan control contacts on the thermostat according to the thermostat wiring diagram. When the temperature reaches the start value, the contacts close to start the fan; when it drops to the stop value, the contacts open to stop the fan. When wiring, ensure that the rated capacity of the contacts matches the fan’s power rating.

3. Data Diagnostics

3.1 Q: Is it normal for there to be an imbalance in the temperatures of the three-phase windings?

A: Three-phase current imbalance can cause temperature differences among the three-phase windings; slight variations are normal. If the temperature of one phase is significantly higher than that of the other two, you should check whether that phase is overloaded or if the sensor is malfunctioning.

3.2 Q: How can temperature data and oil chromatography data be analyzed in conjunction?

A: A persistently high oil temperature accompanied by a simultaneous increase in characteristic overheating gases such as ethylene and methane is a typical indication of an internal overheating fault. If the oil temperature is high but the oil gas analysis is normal, the problem is usually related to the cooling system or overloading.

3.3 Q: What is the purpose of historical temperature data?

A: After establishing temperature baselines for the transformer under different seasonal conditions and load levels, compare the current temperature with the historical baselines. Deviations from temperature trends are more diagnostically valuable than absolute temperature values.

4. Maintenance and Repair

4.1 Q: Do the electrical contacts of the thermostat require maintenance?

A: The contacts of the microswitch may become oxidized or develop poor contact after prolonged use. We recommend inspecting and cleaning them once a year to ensure reliable operation at the set temperature.

4.2 Q: What should I do if the capillary tube on the oil-filled thermostat is leaking?

A: A broken capillary tube will cause the internal temperature-sensing medium to leak, preventing the thermostat from functioning properly. A broken capillary tube usually cannot be repaired on-site; the entire thermostat must be replaced. Special care should be taken to protect the capillary tube during installation.

Disclaimer: The content of this article is for technical exchanges and reference only, and does not constitute any form of procurement commitment or contract offer. Product technical parameters, configuration programs and prices are subject to the actual signed contracts and technical agreements.

Have more questions about transformer temperature monitoring technology? Feel free to contact Innotongda for expert advice. Service Hotline: 13959168359 (also on WeChat).