Maintenance, repair, and servicing of transformers in Vietnam

This is an important task that needs to be carried out to prevent accidents and minimize risks for everyone. Some contents that need to be implemented to ensure safety include:

• When performing maintenance and repairs, the voltage transformer must be disconnected from the high-voltage grid, and the secondary circuit breakers of the voltage transformer must be in the open position.
• All machinery and equipment must be stopped during maintenance and repair.
• Notify everyone of the time of maintenance and repair, and have signs such as “Under maintenance, do not turn on the power.”
• Ensure the machine is stopped before moving or opening the protective cover.
• Keep the machine away from flammable materials and substances. Do not use gasoline, oil, and flammable substances to clean the machine.
• Reinstall intact protective equipment and machine covers after maintenance.
• If welding on any part of the machine, follow the instructions.

2. Regular maintenance of voltage transformers.

In fact, the repair costs due to sudden equipment failures, reduced machine life, productivity losses, etc. are much higher than maintenance costs if detected early and prevented from occurring.

Regular transformer maintenance checks will help us detect any abnormalities in the machine, thereby predicting and preventing breakdowns and machine errors before they occur by performing regular maintenance every month, 3 months, or 6 months. The goal is to be less, shorter, and able to predict the machine failure.

a. Contents of regular transformer maintenance checks

Check the surface of the insulation porcelain, whether the porcelain heads have cracks, dirt, or oil leakage?

Check the MBA casing for integrity and oil leakage?

Check the color, insulation level, and oil level of the auxiliary oil tank, the insulation porcelain with oil, oil pressure in the pressure porcelain.

Check the readings of the thermometer and pressure gauge.

Check the cooling system and continuous oil regeneration equipment.

Check the operation of the Steam Relay, safety valve, explosion-proof glass tube, and the position of the valve between the steam relay and the auxiliary oil tank.

Check the signaling devices.

Check the cable heads, conductive bars, joints, and see if the contact is overheating?

Check the MBA grounding system and protection devices.

Check if the machine makes any abnormal noises?

Check the color of the moisture-absorbing beads, if it turns from pink to light yellow, replace the beads.

Check the condition of the machine room: windows, doors, ventilation holes, lighting, and protective screens.

Check the firefighting equipment.

b. Regular maintenance of the transformer:

It is maintenance and repair of MBA with power cut, but without draining the oil or opening the core. The regular minor maintenance can be performed every 3 or 6 months depending on the actual working conditions, with 3 months being the recommended interval.

The minor maintenance of MBA includes the following contents:

• Check and repair minor damages that can be immediately fixed.
• Clean the MBA location and its components (cooling fins, machine casing, high/low voltage insulating ceramics…).
• Check and clean all connecting bolts, tighten nuts and screws.
• Filter dirty oil from the auxiliary oil tank, supplement the auxiliary oil tank, flush the drain pipe, and check the oil level gauge.
• Check the color of the desiccant beads (if it turns from pink to light yellow, replace the desiccant beads).
• Check the operation and clean the pressure relay, safety valve, and signaling devices.
• Check and clean the cooling system, replace the grease of the cooling system’s motor bearings.
• Check the grounding wire connections of the MBA casing, protective and lightning devices, and ensure that the connections are secure during operation.

c. Regular major maintenance of the transformer: