Transformer Auxiliary Protection Devices: Part 1 : Oil level indicator (71)

Auxiliary Protection:

1. Oil Level Indicators (71)

2. Thermal Protection (26, 49)

3. Sudden Pressure Relays (63)

4. Gas Accumulators and Buchholz Relays (80)

5. Dissolved Gas and Moisture Monitors

6. Bushing Monitors

In this article you will review and read about Transformer oil level indicator

Part 1 : Oil Level Indicators (71)

In oil-immersed transformers, transformer oil mainly plays the role of insulation and cooling. An oil level indicator for a transformer is a device that measures the level of oil in the transformer as it helps to dissipate heat and insulate the windings and protects the transformer against arcing and corona discharge.

The oil level indicator in a transformer is designed to measure both the minimum and maximum oil levels.

The oil level indicator provides a visual indication of the oil level, allowing operators to take appropriate action if the level is too low or too high.

The location of the oil level indicator in a transformer can vary depending on the design and type of transformer. In some transformers, the oil level indicator is installed on the top of the transformer tank, while in others, it may be located on the side or bottom of the tank.

In general, the oil level indicator is installed at a height that allows for easy visibility and access for maintenance and inspection. It is usually positioned in a way that allows the operator to read the oil level without having to climb on top of the transformer or use special equipment.

The exact location of the oil level indicator can also depend on the size and capacity of the transformer. For larger transformers, multiple oil level indicators may be installed at different locations to provide a more accurate reading of the oil level.

Oil level too high

What are the consequences of increased oil level in transformers?

An increase in oil level in a transformer can have several negative impacts on its operation and performance. Some of the common influences of increasing oil level in a transformer include:

1. Reduced Insulation Performance: When the oil level rises above the recommended level, it can cause the insulation materials inside the transformer to become saturated with oil. This can reduce their dielectric strength and increase the risk of insulation breakdown.

2. Overheating: An increase in oil level can reduce the cooling capacity of the transformer, leading to overheating. This can cause damage to the transformer and reduce its lifespan.

3. Oil Leakage: If the oil level rises above the maximum level, it can cause the oil to leak out of the transformer. This can create a safety hazard and cause damage to the surrounding environment.

4. Reduced Efficiency: An increase in oil level can reduce the efficiency of the transformer, leading to higher energy consumption and increased operating costs.

5. Reduced Lifespan: Over time, an increase in oil level can cause damage to the transformer, reducing its lifespan and requiring costly repairs or replacement.

It is important to monitor the oil level in a transformer regularly and take corrective actions if the level rises above the recommended range. This can help ensure safe and efficient operation of the transformer and prevent any negative impacts on its performance.

What should be checked after increasing the transformer oil level?

If the oil level in a transformer has increased, there are several steps you can take to identify the cause and take corrective actions. Here are some of the steps you can follow:

1. Check the oil level gauge: The first step is to check the oil level gauge to ensure that it is accurate. Sometimes, the gauge may give a false reading due to a faulty gauge or other issues.

2. Check for leaks: If the oil level has increased, it may be due to a leak in the transformer. Check for any signs of oil leakage around the transformer, including the gaskets, bushings, and other components.

3. Check the breather: The breather is a device that allows air to enter and exit the transformer as the oil level changes. If the breather is clogged or damaged, it can cause the oil level to rise. Check the breather and clean or replace it if necessary.

4. Check the cooling system: The cooling system in a transformer helps to dissipate heat generated during operation. If the cooling system is not functioning properly, it can cause the oil level to rise. Check the cooling system, including the fans, radiators, and pumps, and repair or replace any faulty components.

5. Check the tap changer: The tap changer is a device that allows the transformer to adjust the voltage output. If the tap changer is not functioning properly, it can cause the oil level to rise. Check the tap changer and repair or replace any faulty components.

6. Check the transformer for internal faults: If all the above steps have been checked and no issues have been found, it may be necessary to perform tests to check for internal faults in the transformer. This may include insulation resistance tests, winding resistance tests, and other diagnostic tests.

If it is caused by overload, the load should be reduced.

If the three-phase current is seriously unbalanced and the current of a certain phase exceeds the rated value. The load should be adjusted to achieve a basic balance.

If the cooler is abnormal, the temperature of the transformer oil rises. Oil expands when heated. cause the oil level to rise. Then check whether the cooler is blocked by dust accumulation, and whether the upper and lower valves of the oil pipe are open. Whether the fan and submersible pump are running normally. Whether the temperature of the cooling medium is appropriate, etc. Prompt treatment returns the cooler to normal operation.

If the oil level is too high due to excessive oiling of the transformer, the oil should be drained to an appropriate height.

It is important to note that any maintenance or repair work on a transformer should only be performed by qualified personnel with the necessary training and experience.

Oil level too Low

Decreasing oil level in a transformer can have several negative impacts on its performance and lifespan. Here are some of the effects of low oil level in a transformer:

1. Reduced cooling capacity: The oil in a transformer acts as a coolant, and if the oil level drops, the cooling capacity of the transformer is reduced. This can cause the transformer to overheat, which can lead to insulation breakdown and other issues.

2. Reduced insulation: The oil in a transformer also acts as an insulator, and if the oil level drops, the insulation between the windings can be compromised. This can lead to arcing and other electrical faults.

3. Increased noise: A low oil level can cause the transformer to vibrate and produce more noise than usual. This can be a sign of impending failure.

4. Reduced lifespan: A transformer with low oil level is more likely to fail prematurely due to the increased stress on its components.

If the oil level drops to below the minimum level, it can cause serious damage to the transformer. Here are some of the consequences of low oil level:

1. Overheating: A low oil level can cause the transformer to overheat, which can lead to insulation breakdown and other issues.

2. Short circuits: A low oil level can cause the windings to come into contact with each other, leading to short circuits and other electrical faults.

3. Catastrophic failure: If the oil level drops too low, it can cause the transformer to fail catastrophically, which can result in a fire or explosion.

Therefore, it is important to monitor the oil level in a transformer regularly and maintain it within the recommended range to ensure its safe and efficient operation.

After decreasing or increasing oil level in a transformer from min. and max. preset levels, an alarm will be triggered. These alarms are usually relayed to the control center.