Distribution System Training

The objective of this module is to examine the major functions of distribution substations, including different arrangements of substation layout. Typical bus configurations are presented along with a look at the equipment usually installed in substations.

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

• The role of the substation, i.e. link between the high voltage system and distribution customers
• Operating activities performed in the substation
• Substation bus arrangements; high voltage and low voltage
• Single feed and dual feed substations
• Dual transformer substations
• The use of mobile transformers
• Metal clad switchgear arrangements
• Substation local and remote operation
• Switching devices used in the substation
• Features of the circuit breaker
• Types of quenching medium used in circuit breakers
• Switching procedures
• Location of protection relays in substations
• Characteristics of the basic disconnect switch (non-load break)
• The application of disconnect switches in clearance procedures
• The interruption of line charging current and transformer excitation current
• Discharging static voltage to ground, and applying temporary grounds
• Application of the fused disconnect combination
• Substation equipment
• Station service supply to the substation
• Applications of auxiliary power
• DC supply and applications
• The station battery
• Uninterruptible power supplies
• The application of instrument transformers; i.e. CTs (current transformers) and PTs (potential transformers)
• Handling monitoring data
• Communicating monitored data to the system control center via the SCADA system
• Voltage control equipment; i.e. automatic tap changers and capacitor banks
• The substation-grounding mat
• Grounding of metallic equipment, enclosures, and structures
• Connection of other system grounds; i.e. the neutral point of Wye connected transformers
• Unattended substations