Commonwealth was selected by Avista to design the complete rebuild of Dalton Substation. The substation redesign was needed to increase the transformation capacity, improve line protection around the substation, improve distribution reliability and for the replacement of outdated equipment.
The new Dalton Substation design includes two-line breakers, two transformers with breaker protection and six distribution feeders to increase the distribution and additional load serving capacity. Except for two steel structures, everything was redesigned and replaced. The final design configuration consisted of the 115 kV transmission looped-through the substation. Each line has a 115 kV gas circuit breaker with disconnect switches on each side and were tied together by a 115 kV main bus without a sectionalizing switch.
One challenge during this project was keeping the substation functional while replacing the equipment. To address this, Commonwealth had to come up with a design which staged construction and utilized a mobile substation that kept the substation active and energized during construction. Commonwealth delivered the expertise and resources needed to get the design done well in advance of the start of construction.