New Paralleling Switchgear for Distributed Generation

Diesel Progress North American Edition, May, 2001 by Mark McNeely

These days, a hot topic among owners of diesel generating assets, or those considering the initial investment for on-site power generation, is whether or not to install a swithgear system that is capable of paralleling with the utility.

In an effort to provide a solution for these potential distributed generation applications, Shallbetter Inc., and ZTR Control Systems have developed the DGX switchgear. DGX is designed to parallel a single generator set to a utility, although the operation and features of DGX can also be incorporated into multiple gen-set paralleled systems. Additionally, DGX can upgrade existing gen-sets and nonautomatic switchgear in order to take advantage of different utility rate programs.

"From the beginning, the DGX product has been designed for both new installations and to retrofit existing systems," explains Dariush Akhavan, director of sales and marketing for ZTR Control Systems.

DGX can be manufactured to accommodate low and medium voltage applications, with many standard modes of operation based on the models selected to meet individual applications, including standby, isolated, load curtailment, load management, peaking and power export.

The design, development, manufacturing, sales and training for the DGX switchgear are all part of a unique partnership between Shallbetter and ZTR Control Systems.

Shallbetter Inc., located in Oshkosh, Wis., was established in 1982 and since then has been a key player in switchgear manufacturing in the utility environment. Shallbetter produces power distribution products up to 38 kV, including pad-mounted swichgear, primary metering, fuse gear and capacitor banks. Its customers include power generation producers and system packagers in industrial, utility, commercial and mining markets.

Since 1987, ZTR Control Systems, Minneapolis, Minn., has been in the business of providing monitoring and control systems for power generation, wastewater treatment, landfill facilities and other custom applications.

"We call it a Power Partnership and this partnership has created the DGX product," said Jim Bell, vice president of power generation equipment for Shallbetter. "The Power Partnership is more than a catchy marketing term. The goal is to provide our customers with best solutions in products and services with emphasis on quick delivery.

"Both Shallbetter and ZTR have common goals and objectives in the power generation field," Bell continued. "We have sought out this long-term relationship with each other and, subsequently, our customers. Our products complement each other and together we provide single source responsibility for power generation-related products."

To that end, responsibilities for the DGX switchgear include manufacturing and sales under Shallbetter, while engineering and monitoring systems are the responsibility of ZTR. Both companies participate in site commissioning.

"We have also established formal technical training programs for DGX on two levels," Akhavan said, "For technical sales people, including manufacturers representatives and generator set distributors, training assists in providing effective application guidance to customers. For generator set service personnel, training helps to ensure proper commissioning, service and setup.

"Although we offer training, DGX is what we call TechReady," Akhavan said. "It is designed to allow ease of setup, operation and change of parameters. The system is very user friendly with intuitive controls. You don't need a PC to setup and configure a IDGX."

The standard configuration of the DGX switchgear is equipped with a multifunction Schweitzer model SEL-351A relay to provide protective relaying for utility applications. The relay functions can be selectively turned on and off per project requirements. The gen-set protective relay functions are an integrated feature of the gen-set controller. The 3-phase sensing functions include 27/59, 40, 810/U, 32R, 25, 51 and load surge.

The DGX also features a Woodward EGCP-2 fully integrated digital generator control and engine management system that provides automatic sequencing, automatic synchronization, real power, reactive power, power factor and soft load controls. The EGCP-2 provides true RMS power calculations for accurate load control even in the presence of harmonics.

Akhavan said, "We wanted to select components that are proven, accepted, reliable, and easy to set up and work with. Probably the most important factor is ease of troubleshooting and components such as the EGCP-2 and SEL relays meet these criteria very well."

For custom applications, DGX switchgear offers options including SEL-351-2 or Beckwith protective relays, manual synchronizing, NEMA 3R or 4X stainless construction, surge arrestors and capacitors.

Every DGX switchgear is also equipped with a ZTR-Lynx monitoring and supervisory control system, which continually monitors the generator set and switchgear parameters and records alarms and events. The system ran also send an alarm page using its internal modem. The monitoring system also provides the user with a license for one copy of ZTR-Lynx off-site HMI software, a Windows-based software that allows the operator to connect to the monitoring system either locally or remotely.