Distribution System Training

The objective of this module is to demonstrate and discuss the main features of underground distribution systems, including typical arrangements for rural, suburban and city areas.

After completion of this module, the participant should understand the following concepts, and apply them in day-to-day work practice.

• Construction of different types of underground cables
• Features of solid dielectric cables
• Features of paper insulated lead covered cables
• The purpose of the conductor shield and insulation shield
• Single conductor cables and three conductor cables
• The single conductor cable with concentric neutral
• Features of cable splices and cable terminations
• Underground residential distribution
• Direct buried primary and secondary cables
• Pad mounted transformers and switchgear
• The open loop arrangement
• The application of elbow disconnects
• The application of flexible ducts to protect direct buried cables
• Secondary circuit connecting points, i.e. hand holes and pedestals
• Protection for URD primary feeder, distribution transformer, secondary underground cable, and customer’s circuits
• The application of fault indicators
• Underground cable ampacity
• Underground supply to concentrated loads
• Alternate supply arrangements
• Underground distribution in city downtown areas
• The application of ducts and manholes beneath street level
• Transformer vaults
• Circuit identification
• Other underground services requiring co-ordination
• High rise distribution feeders (primary risers)
• The spot network to provide uninterruptible supply to critical loads
• The downtown secondary grid
• Function of the network protector
• Secondary cable faults