Duluth Transit Authority Electric Bus Charging Design

Duluth, Minnesota

The Duluth Transit Authority was recently selected for a $6.3 million grant from the Federal Transit Authority for fully electric buses. Duluth is the first city in Minnesota to use these buses and one of 10 public transportation organizations in the country to take the first step toward zero-emissions public transit. SRF designed the electrical distribution system for eight permanent depot chargers for overnight charging at the DTA maintenance facility. The system is designed for future expansion for up to 20 chargers rated at 60 kW each. The design included coordination with the local utility for a new 1000 kVA transformer and service dedicated to the charging system, a 480V/1600A switchboard with a service rated automatic transfer switch for a 250 kW generator to provide partial system charging in case of longer term power outages. The system was also designed for communication networking capability for the chargers, switchgear and generator including a remote annunciator panel.