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Electrical Transformers: Electrical Transformers Installation Tips

Electrical Transformers Installation Tips


electrical transformer
Photo Courtesy vaxomatic

Installing an electrical transformer at the job site can be difficult specially if it is your first time or you are not familiar with electrical transformers. First of all the electrical transformer must be handled carefully, otherwise it could suffer internal damages leaving you with a useless power equipment. It is important to follow all safety precautions and provide safety equipment to the construction worker handling the transformer. These tips can be used on installation for both dry-type and liquid-filled transformers. It is important that your know what acceptance tests should be carried out. All required acceptance tests should be following ANSI/IEEE and NEMA approved standards.

Electrical Transformer Placing

  • Ground

When considering the location where the electrical transformer will be installed, is important to evaluate all safety codes and such installation should not present any threat to normal movement of personnel or equipment. If the electrical transformer is installed at ground level, it is important to evaluate soil characteristics and soil behavior. Poor soil conditions can lead to differential settlements damaging your transformer o electrical connections. If the electrical transformer is to be installed over a concrete pad, is must have at least 3,000 psi, with chamfered edges on top of the base extending 20 inches down from each end, and a typical base should be 6 by 7 feet and 12 inches.

For pad mount transformers with ratings 75kVA through 500kVA, a typical concrete base would be 5 1/2 by 6 1/2 ft and 10 in. For units with ratings above 500kVA to 2500kVA, a typical concrete base would be 8 ft by 9 ft and 10 in. thick .

  • Inside a Building or on Top of a Structure

If your electrical transformer is to be installed inside or on top of a building, careful provisions and structural analysis of such load must be analyzed and considered into the structural design. Special provisions should be taken on seismic-prone areas to avoid collapse during an earthquake or seismic movement. For any condition it is highly recommended if your manufacturer can present a schematic or drawing of the electrical transformer.

Electrical Transformer Installation Tips

An electrical transformer should be inspected for damage prior to installation. Please be sure to check and visible damage, loose or broken parts, dirt, or the presence of moisture. If these signs are not visible, then your transformer should be in good conditions and ready to be installed.

  • Avoid any additional stress imposed by incoming cables on transformer bushings or connections.

  • Do not remove the protective coating around terminals. They prevent surface oxidation.

  • If aluminum conductors are used, protect them as specified by manufacturer's.

  • The electrical transformer manufacturer should provide instruction or details about torque requirements.

  • Use only UL listed lugs and follow manufacturer's recommendations on how to attached them.

  • Avoid installing washers between terminal lugs and the bus bar. Doing so can overheat the connection.

  • Provide proper clearance for cable and avoid installing them near blades or coils. Follow minimum wire bending space clearances at terminals for conductors per NEC.

  • If required follow NEMA standards for transformer sound control depending upon the kVA rating of a unit.

  • Ground, ground and don't forget to ground. Follow NEC recommendations and the check the grounding of the neutral as applicable.

  • Check the correct function of control circuits by performing an insulation resistance test. BE CAREFUL not all transformers can withstand the applied voltage.

  • All windings should be checked for continuity.

  • An insulation resistance test shall be made prior to energizing the electrical transformer.

  • If the electrical transformer is going to be operated in parallel, consult with the manufacturer that all voltages, impedances, and turn ratios are appropriate.

  • Before energizing and 3-phase electrical transformer compare the line to ground and line-to-line voltages, they should be similar.

  • After installation is complete, check the output voltage of the electrical transformer.

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