Underground Residential Distribution Transformers

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Code: URTA
View for 1 month: $4

This 59-minute video covers the basic principles of operation of pad-mounted transformers and switchgear, the types of equipment that are in common use, and how they are connected. It also presents the basic principles of pad-mounted transformer and switchgear inspection and troubleshooting, and shows an example of how to detect a problem with one leg of a three-phase transformer.

Training Sessions

Verifying the Power Outage – 6 minutes
Uses diagrams to locate the transformer, or transformers, that feeds houses reporting a power outage. Determines if residential customers reporting power outages are actually not getting power. Determines if a problem in the primary circuit is the cause of a power outage.

Identifying a URD System Fault – 7 minutes
Uses diagrams to find a particular transformer in a URD system. Takes a voltage reading of a transformer’s secondary output. Explains, with a schematic diagram, how a blown fuse could cause a transformer to have no secondary output even though it is receiving primary power. Explains, with a diagram, how to de-energize a transformer without interrupting power to customers fed by other transformers in the circuit.

Isolating a URD Transformer – 9 minutes
Covers how to: use a primary schematic and a construction print (or similar system drawing) to find a tie point, make a tie, isolate a suspected faulty transformer, and test a transformer and its primary cables to make sure that they are de-energized.

Testing a URD Transformer – 7 minutes
Explains how to: safely remove a transformer fuse for testing, install a new fuse in a URD transformer, re-energize a URD transformer, and disconnect secondary cables.

Disconnecting a URD Transformer – 10 minutes
Covers how to: install grounds on primary cables, remove primary cables from a transformer, disconnect the neutrals and the case ground from a URD transformer, obtain information necessary to order a replacement URD transformer, and recognize various types of URD transformers.

Replacing a URD Transformer – 8 minutes
Explains how to: install a replacement URD transformer, test the replacement transformer for proper operation, restore transformers and cables on either side of the replacement transformer to their original conditions, and disconnect the tie point.

Support Materials Available

Student workbook, instructor guide.