Maintenance and Care of Transformers

Maintenance and Care of Transformers:

Regular maintenance of transformers is essential to ensure their proper functioning and longevity. Here are some important maintenance and care practices for transformers:

1. Ventilation and Environment: Keep the transformer well-ventilated, clean, and dry. The area around the transformer should not be used for storing spares or other items. Proper ventilation is crucial to prevent overheating of the transformer.

2. Permit-to-Work: Before performing maintenance tasks, issue a permit-to-work and disconnect the transformer from the power supply to ensure safety.

3. Insulation Resistance Measurement: Measure the insulation resistance between phase windings and earth using a megger. If the value is low, it indicates the presence of dirt, dust, or moisture. Cleaning and heating may be required to remove these contaminants.

4. Cleaning: Remove the top cover of the transformer and clean the protective grids and screens. Use a brush or vacuum cleaner to remove dirt and dust. Avoid using compressed air, as it can force deposits into the insulation.

5. Moisture Removal: If moisture is present, it can be removed by heating. Take caution not to exceed safe temperature limits during this process.

6. Insulation Resistance Measurement (Phase to Phase): Measure the insulation resistance between phase windings using a megger. If the value is low, it indicates a short circuit in the windings, which requires further investigation.

7. Visual Inspection: Visually inspect the transformer for signs of burning, damage, or loose connections. Repair or replace any damaged components as necessary.

8. Varnishing: Apply varnish to the windings to enhance insulation and protect against moisture.

9. Reassembly: Replace screens, protective grids, and the top cover of the transformer. Ensure all terminals are tightened securely.

10. Measuring Instruments: Use appropriate measuring instruments to measure electrical quantities such as current, voltage, power, and insulation resistance. Common types of measuring and indicating instruments include PMMC (Permanent Magnet Moving Coil) type, MI (Moving Iron) type, and Electrodynamometer type.

11. Electrodynamometer Type Measuring Instrument: This instrument works on the dynamometer principle, where mechanical force is generated between two current-carrying conductors or coils. It consists of two fixed coils and one moving coil attached to a shaft with a pointer. The interaction between the magnetic fields of the coils causes deflection of the moving coil and the pointer, indicating the measured quantity on a graduated scale.

Regular maintenance, inspection, and testing of transformers are crucial to identify and address any issues promptly, ensuring their reliable and safe operation. It is recommended to follow manufacturer guidelines and consult qualified professionals for specific maintenance procedures.

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