Equipment Pre-Specification Studies 

 

Insulation Coordination Studies

Topics:
Swit​ching overvoltages, lightning overvoltages, ferroresonance, very fast transients
Focus:
GIS/AIS substation equipment (such as circuit breakers, disconnect switches, buswork, bushings, and instrument transformers), power transformers, cables, transmission lines, surge arresters, other power system and monitoring equipment associated with GIS/AIS equipment
Recommendations:
Surge arresters (i.e., proper ratings, location, and surge arrester grounding practices), switching restrictions, synchronous switching, pre-insertion resistors, surge capacitors, ferroresonance suppression devices, defined equipment Basic Switching Impulse Insulation Level (BSL) and Basic Lightning Impulse Insulation Level (BIL) ratings, grounding and bonding modifications
 
 
Grounding, Bonding, and Step-and-Touch Voltage Studies
Topics:
Step voltages, touch voltages,
metal-to-metal touch voltages, grounding wire currents, bonding bar/wire currents
Focus:​
Substation bus, GIS enclosure,
ground grid, bonding bars/wires,
soil, surface material
 
Recommendations:
Need for or verification of improved grounding and bonding