The Public Works building had an existing 600 V, 800 KW generator designated for emergency backup electricity in the event of loss of electricity from the electrical utility.
A portion of the City's electricity bill every month was due to peak KW demand during winter months. The high peak KW demand set in the winter is applied as a KW demand charge to a year of subsequent monthly bills. There was an opportunity to operate the generator a few times a year during the coldest times in winter months to reduce the peak KW demand and avoid paying a high KW demand charge for many months. The savings on the electricity bills was much more than the cost of some fuel used for a short duration to reduce this peak.
Power Precision designed and built new controls and 600 V switchgear to take the place of the existing transfer switch. The new 1200 Amp breakers and bus were built on a single backpanel. The components of the existing transfer switch were removed and the new backpanel was installed into the same existing enclosure previously used by the transfer switch and connected to the existing power cables.
A generator and switchgear controller was installed in another enclosure separate from the 600 V components for arc flash safety. The new controller is connected to the generator engine controls. The controller is connected to the City SCADA system for remote control and monitoring of new controller and generator information via a data communication network.
With the new switchgear and controls, the same generator will provide electrical power generation for peak-shaving in addition to maintaining its function as a backup emergency generator.
For peak shaving operation, the generator will synchronize and operate in parallel with the electrical utility and backfeed electrical power onto the electricity grid. In the event of a power failure from the electrical utility, the generator will provide electricity to the Public Works Building islanded from the utility until utility power returns.
Now, with the ability to synchronize, the generator will connect and disconnect without any disruption to the electrical supply for testing and peak shaving operation and to make a bumpless transfer of the Public Work building loads back to utility power after operating as an emergency backup supply.