Power Transformer Guidelines When Making Internal Inspections

Power Transformer Guidelines When Making Internal Inspections and Free Download pdf Ebook


1. Before climbing on the transformer, remove anything that may contaminate it and cause it to fail when energized: Remove all especially metal items from pockets and other loose items such as watches and rings. Wipe shoes clean of mud, stones, and other foreign material. Put clean disposable booties over shoes prior to entering the transformer. Attach lines to tools used in tank or near open manhole so that they cannot accidentally be dropped in the transformer.

2. Check the gasket of a power transformer before replacing the manhole covers.

3. For strick compliance no one should enter confined spaces for repair without prior authorization and review of applicable Company safety rules and General Safety Procedures for Confined Space Entry.


4. Do not permit the coils and insulation to be exposed to the air. You should lower the oil to the top of the core and coil assembly. Oil must be passed through an approved filter system. For oil-filled units power transformer.

5. Do not open transformers during periods of fog or precipitation or when relative humidity exceeds limits outlined in the manufacturer’s instruction book. If no value is specified in the instruction book, use a limit of 75%.


6. After sealing the transformer,unless it is the open type, it should be pressurized with dry nitrogen and purged until oxygen content is less than 1%.

7. It is advisable to check always the oxygen content before you entry and also monitor while you are inside the power transformer tank. Just be sure that the acceptable level of the oxygen is 19.5 percent.

8. Maintain a flow of dry air through the tank while it is open to help keep the insulation dry.If the core and coils are not covered with oil.

9. Do not allow transformer to stand open any longer than is necessary because of its tendency to absorb moisture from the air.

10. You should wear the proper attire during installation or repair of a power transformer.


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Instructions Manual
Installation, Operation, and Maintenance of Medium Power Substation Transformers, Although all transformers, components, and accessories
are carefully inspected and tested prior to shipment,  a thorough receiving inspection should be conducted to detect any damage or loss that might have occurred during shipment.

An Important OverView about Power Transformers for Electrical
Transformer is the most important unit in an electrical distribution network. All transformers are subjected to thorough tests at the manufacturer’s works before despatch to the destination of erection.Due to limitations in transport, large capacity transformers are dis-assembled into various components before despatch.

Transformers Basics, Maintenance, and Diagnostics
Transformers have been used at powerplants since the inception of
alternating-current generation, a century ago.  While operating
principles of transformers remain the same, the challenges of
maintaining and testing transformers have evolved along with
transformer design and construction.

TRANSFORMER INSTALLATION MANUAL
The purpose of this Instruction Manual is to provide guidance on the installation, commissioning and
maintenance of oil-filled transformers. This guide is necessarily general in nature.