California Natural Products (CNP; Lathrop, California, U.S.), a natural food processor of rice-based ingredients, saw the opportunity to lower its electric bill by 2% by installing an efficient on-site power system. Given California's precarious power situation and resulting efficiency incentives, the economies would be even better if the on-site power system were designed for cogeneration, allowing heat from power generation to be incorporated into CNP's manufacturing processes.

Almost a thousand miles away, another food industry firm, NOBLE/SYSCO, wanted to ensure the production of its 17,000 items continued round-the-clock at its 430,000-sq-ft (40-sq-m) facility in Denver, Colorado, U.S. NOBLE/SYSCO worried that even a brief power outage would have a resounding impact on its 24-hour operation.

Although CNP and NOBEL/SYSCO had differing reasons, both companies were in search of on-site power system solutions. After preliminary evaluations of needs and opportunities, both companies incorporated solutions provided by Encorp (Windsor, Colorado), which provides a broad spectrum of hardware and software controls specifically designed to support distributed generation operations. Each solution was based on natural-gas genset power sources and included Schweitzer Engineering Laboratories' (SEL; Pullman, Washington, U.S.) microprocessor-based relays for monitoring, control and protection.

CNP decided to install a combined-heat-and-power (CHP) system after learning about California's incentive program that covers nearly one-third of the total costs for such projects. CNP, which produces a wide range of food ingredients from conventional and organic rice, such as syrups, flours and sweeteners, would save hundreds of thousands of dollars in upfront power-system costs through the state incentive program.

Completed in February 2003, the new system is powered by a 1350-kW Deutz natural-gas engine. Including technology designed by Encorp, the system will run 24/7, and is expected to produce more than 9.4 million kWh each year. In addition to generating electricity when needed, the system will turn excess engine heat — often considered an unusable byproduct of an on-site power system — into a tool that helps process rice and other ingredients in the company's round-the-clock manufacturing process.

To protect the power system, Encorp selected micro-processor-based SEL-351 directional overcurrent and reclosing relays and SEL-300G generator relays for their robust functions and features.

A deciding feature was the Sequence of Events Recorder (SER) included with the SEL-351 and SEL-300G models, providing interconnection protection such as under power (32U), over/under frequency (81O/U), voltage restrained/neutral overcurrent (51V & 50/51N), over/under voltage (27/59) and neutral overvoltage (59N).

The SEL-351 offers additional logic to integrate PLC functionality. For the CNP project, Pacific Gas & Electric (San Francisco, California, U.S.) required backup systems for microprocessor-based relays, so Encorp elected to install redundant SEL-351 devices.

Encorp engineers connected the SEL-300G generator relay and both SEL-351 relays via serial port to a system communications module, which allows Encorp to dial in and view the relay settings, and download sequential event reports. Being able to remotely access the relay saves time and travel, and assists in the accuracy of troubleshooting power-system events.

Because NOBEL/SYSCO needed a safety net to ensure power reliability, the company installed two Cummins/Onan generator sets — a 750-kW DFHA and a 1500-kW DFLE — supplied by Cummins Rocky Mountain — to provide backup power in the event of a power outage. However, after talking to representatives at Xcel Energy (Minneapolis, Minnesota, U.S.), the local utility, NOBEL/SYSCO learned about the substantial cost savings possible through the utility's curtailable-rate program.

This innovative program allows Xcel Energy to periodically ask NOBEL/SYSCO to turn on its backup generators and draw power only from the generators — not the utility — during times of peak energy use. The program is a win-win for NOBEL/SYSCO and Xcel. NOBEL/SYSCO can reduce its utility bill thousands of dollars each month (up to a 12% reduction each month). At the same time, Xcel can ensure it has an additional 2 MW of electrical capacity available to serve customers during peak times.

To participate in the curtailable-rate program, however, NOBEL/SYSCO needed additional equipment to ensure a seamless transition from utility power to generator power. The company contracted with Encorp to supply two automatic transfer switches (Encorp ATS 4000), which instantaneously transfer NOBEL/SYSCO's facility loads of 1200 A and 2500 A to the generators, and two Encorp Utility Power Controls, which provide safe, reliable transfer between each generator and the utility grid. The Encorp equipment also ensures seamless transitions when it's time for NOBEL/SYSCO to return to utility power.

The technology-neutral Encorp equipment easily interfaces with an Andover Control system already in place at NOBEL/SYSCO. The Andover Control system is a complete building automation system that monitors security, lighting and other electrical services on site. To monitor and protect the system, Encorp installed SEL-351 relays, which provide interconnection protection such as reverse power (32R), neutral overcurrent (50/51), directional current (67), over/undervoltage (27/59), neutral overvoltage (59N) and synch check (25). With the Encorp equipment, NOBEL/SYSCO expects a quick return on investment thanks to the substantial energy savings. Also, company officials are assured of reliable power to meet the demanding round-the-clock production schedule.
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