Transformer Temperature Gauge & Oil Sample Valve: Industry Knowledge Guide
1. Transformer Temperature Gauge & Socket
Purpose
The transformer temperature gauge is a critical monitoring component installed in the thermometer socket of the transformer tank, used to:
Continuously measure and display the top oil temperature of the transformer, reflecting the actual operating status and load level.
Provide visual reference for over-temperature alarms and cooling system control.
Help identify potential faults such as overload, poor cooling efficiency, or internal overheating.
Working Principle
Most models are pressure-type (liquid-filled) temperature gauges:
The temperature bulb (in the socket) is filled with thermal-sensitive liquid or gas, immersed in transformer oil.
As the oil temperature rises, the liquid expands, generating pressure inside the capillary tube.
The pressure drives the internal Bourdon tube mechanism to rotate the pointer, directly indicating the temperature on the dial.
Some models are equipped with alarm contacts to trigger remote signals or interlocks at preset temperature thresholds.
Key Parameters
| Item | Specification |
|---|---|
| Common Model | BWS-75, etc. |
| Measuring Range | Typically 0–150℃ (customizable) |
| Socket Thread | M20×1.5, 27×2, 30×1.5 (standard) |
| Installation Hole | Φ38 on the tank cover (user-prepared flange) |
| Probe Length | 140mm / 210mm (optional) |
Usage & Precautions
Installation:
Install the thermometer socket vertically in the designated hole on the tank cover, ensuring the probe is fully immersed in the oil.
Use the matching sealing gasket to prevent oil leakage.
Operation:
Avoid impact or vibration to prevent damage to the internal capillary and mechanism.
Calibrate the gauge regularly according to the equipment maintenance cycle.
Maintenance:
Check for oil leaks around the socket and gauge periodically.
Clean the dial and probe surface to ensure clear readings and accurate temperature detection.
2. Oil Sample Valve (Oil Sample Cock)
Purpose
The oil sample valve is a dedicated component installed on the transformer tank for:
Safe oil sampling: Extracting small oil samples without stopping the transformer or causing oil leaks, for dielectric strength, moisture, and acidity testing.
Preventing air and moisture from entering the tank during sampling, which would contaminate the insulating oil.
Working Principle
The oil sample valve adopts a one-way sealed structure:
Normally, the internal plug and sealing ring keep the passage closed to prevent leaks.
When sampling, the outlet is connected to a sampling bottle or device. The plug is pushed open to allow oil to flow out, while the one-way seal prevents air from flowing back into the tank.
After sampling, the spring-loaded plug automatically resets to the closed position, maintaining the hermetic seal.
Key Parameters
| Item | Specification |
|---|---|
| Materials | Carbon steel / Stainless steel |
| Type | Integrated copper core oil sample valve |
| Installation Thread | Standard connection matching transformer tank |
| Dimensions | Height: 62mm, Seat diameter: Φ38mm |
Usage & Precautions
Sampling Operation:
Connect the sampling container tightly to the valve outlet before opening.
First drain a small amount of oil to flush the passage, then collect the sample in accordance with the oil testing requirements.
Sealing Check:
After sampling, ensure the valve is fully closed to prevent oil seepage.
Inspect the rubber seal regularly and replace it if aged or damaged.
Safety Notes:
Avoid using excessive force when opening or closing the valve to prevent damage to the sealing mechanism.
Do not disassemble the valve under pressure.
Quick Summary Table
| Component | Core Function | Key Advantage |
|---|---|---|
| Temperature Gauge | Monitor top oil temperature | Direct visual display, easy integration with alarms |
| Oil Sample Valve | Safe, leak-free oil sampling | One-way seal prevents contamination, simple operation |