Medium Voltage Power Systems – Part 2

Synopsis
The backbone of many electric power systems is the medium voltage distribution system. Typically operating at voltages ranging from 2,400 to 34,500 Volts, voltage stress, corona, surges and protection of equipment all create unique challenges in design, equipment selection, operation and engineering.

This 2nd class by Jim Phillips, P.E. takes you through the fundamentals of medium voltage power systems including the components, equipment, design and operation problems as well as protection of medium voltage systems.

Description

CURRENT TRANSFORMER APPLICATIONS
Ratings, Selection Process, Accuracy, Saturation, Excitation Curves, Burden,
Calculation, Momentary Ratings

MEDIUM VOLTAGE CIRCUIT BREAKERS
Vacuum, Air, Oil, SF6 Designs, Symmetrical Interrupting Rating, K-Rated
Voltage Factor, Close and Latch Capability

RECLOSERS
Application on Feeder Circuits, Recloser Settings, Continuous Current and Interrupting Ratings

MEDIUM VOLTAGE FUSES
Medium Voltage Switches, Load Rating, Close and Latch Rating, Short Time Rating, Expulsion vs. Current Limiting Fuse Characteristics, E and R Rated Fuses, Fuse Cutouts

MEDIUM VOLTAGE PROTECTION CONCEPTS
Medium Voltage Protection, Relays, Circuit Breakers, R and E rated Fuses,
Short Circuit vs. Overcurrent Protection

DISTRIBUTION FEEDER PROTECTION
Protection with Fuses – 300%, Overcurrent Protection with Relays – 600%,
Short Circuit Damage Characteristics, Relay “Reach” for End of Line Faults

ROTATING MACHINERY PROTECTION
Requirements, Decrement Curves, Thermal Damage Curves, Reactive,
Capability Curves, Differential Protection

MEDIUM VOLTAGE MOTOR CONTROLLERS
Protection Requirements, Motor Management Relays, Circuit Breaker Protection, Relaying, Class R Rated Fuses

TRANSFORMER PROTECTION
ANSI C57 Thru Fault Curves, Impact of Transformer Winding Configuration,
Overview of Differential Protection, Inrush and Harmonic Restraint