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When Waukesha Engine acquired the technology rights to Wärtsilä’s W200/220 engines in 2004, the company knew from Wärtsilä’s extensive experience with its installed fleet that the engine platform had been well optimized for power generation applications. Waukesha also knew that the 220 mm bore gas engine still had room to grow. With the combination of Waukesha’s proven engine control system and targeted design improvements, the company was certain that the engines would meet the expectations of its existing customers.

Renamed the 220GL (gaseous, lean burn), the engines serve as the backbone for the company’s APG2000 and APG3000 Enginator product lines. With generator outputs of roughly 2.0 and 3.0 MW, respectively, the new Enginators join Waukesha’s existing 1.0 MW range APG1000. Late this summer, Waukesha shipped the first of the new APG3000 units — three Enginators destined for a Russian oilfield approximately 150 km from Novosibirsk, Siberia, where they will meet the site’s electrical power needs.

According to Waukesha Engine, the Wärtsilä 220SG was a particularly attractive product due to a number of innovative and compact design features. The fuel injection system produces load acceptance characteristics similar to that of diesel or naturally aspirated natural gas engines, while maintaining the characteristically low emissions of lean-burn natural gas-powered engines.

The 220GL product line is available in a number of different configurations based upon engine output, frequency, emissions output (1/2 or full TA Luft NOx) and low-temperature water circuit inlet temperature conditions of 45° or 55°C. The combinations equate to 16 different configurations that are optimized to site requirements.

The availability of the different NOx and water circuit temperature ratings provides for a flexible product offering that can fit many different end-user needs. This spans installation varieties from island mode in the desert to the stringent requirements of Europe to the high altitudes of South America. CE marking will be part of the standard scope of supply, making the product suitable for installation into the European Economic Area.

“We’re very excited about the prospects for the APG2000 and 3000. They complement the efforts we have put into the “PG1000,” stated Paul Cannestra, vice president of marketing for the Waukesha, Wisconsin, U.S.A-based company. “When we look at the power generation market on a global basis, the one, two and three megawatt nodes seem to be very key growth segments. We see those as the building blocks for industrialbased markets, as well as for municipalities,
hospitals, universities and other institutions. These engines are just good building blocks for distributed generation applications.”

An important feature of this product that is unique to Waukesha is that it was designed with cogeneration in mind. The standard scope of supply will have engine flanges for the end user to connect piping to an oil cooler. This will allow additional heat recovery and energy extraction beyond the electric power from the generator. It is also possible to recover much of the heat from both water circuits depending on the application specifics.

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“There are certain areas of the world that are really attuned to total heat recovery or CHP applications,” Cannestra noted. “Other parts of the world are starting to see the advantages of total heat recovery, but right now they’re primarily concerned with the need for electrical power to fuel their economic growth. Ultimately, they will begin to see the importance of CHP as well and tap into that part of the business.”

The single biggest change in the transformation from the 220SG to the 220GL was the application of Waukesha’s ESM. ESM is a total engine management system designed to optimize engine performance and maximize uptime. ESM integrates air-fuel ratio control, ignition timing, detonation sensing, governing (fuel injection), diagnostics, fault logging, engine safeties and partial control of start-stop logic. ESM uses CAN communications to transmit and share data between the engine control unit (ECU) and the system’s sensors. ESM system components are all engine mounted and factory tested.

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While ESM has been on the marketplace for a number of years, the 220GL application required additional hardware and software changes for the new sensors and fuel-injection components. This is also the first ESM-equipped engine to offer the integration of individual cylinder exhaust thermocouples with feedback control. Sensors and other feedback elements on the 220GL products provide for comprehensive control and protection, as well as for customers’ diagnostics.

“Our ESM is a common platform for Waukesha Engine,” said Jack Siehoff, director, product development for the company. “Therefore, the main engine control unit didn’t change from a hardware perspective and we reused most of the algorithms just as they apply to our other engines. However, because this is a fuel-injected engine, we had to add some new functionality to our ESM control in the form of injection control units (ICU).”

Each ICU is responsible for injection control of one bank’s worth of main and prechamber injectors. Both the injection duration and specific timing of the injection event are calibrated values under system control. The ICUs can also identify if a solenoid is not working properly and the system will respond accordingly by triggering the corresponding fault.
In order to support the new hardware and sensors, changes were made to the ECU’s native software. This includes the changes to support main chamber and prechamber fuel injection, active cylinder management and cylinder balancing. These changes are hidden to the end user, but are critical to the internal calibration process.

Because the 220GL is fuel injected, rather than carbureted and throttled, the transient response is much closer to that of a diesel than a conventional natural gas-powered engine. The major difference between the two types of engines lies in the fuel delivery system. When a stepped load is applied to the 220GL, the next cylinder to fire can receive, directly from its intake port, the additional fuel necessary to properly maintain engine speed.

Since the main and prechamber injection durations are electronically controlled, the engine can be more accurately tuned for transient response. The wastegate also aids in the fast recovery times, by directing the desired amount of energy to the turbochargers to promote a quick rise in intake manifold pressure. This type of performance makes the 220GL particularly attractive for fast start/load, backup power and island mode applications, according to the company.

As the 220GL product line is introduced through Waukesha’s Enginator line of packaged generator sets, the number of frequency and voltage choices for the generators provides for a wide variety of potential applications for the APG2000 and APG3000. Standard Enginator scope of delivery will find the engine and generator mounted and aligned on a structural steel base, specifically designed and analyzed for this application. It is designed with lifting outriggers and is capable of being either mounted solid or with isolators.

Also part of the standard scope of supply with the gen-sets is the Enginator Control Panel (ECP). It is a comprehensive monitoring and control device for the gen-set and auxiliary devices. It contains items such as the circuit breaker; current, power and potential transformers; a humanmachine interface to display ESM information, operating status, trending, faults and a.c. power information; and engine control via speed and load control with remote start/stop capability. It can also be configured for SCADA to integrate remote access.

During the technology transfer from Wärtsilä in 2004 it became apparent to Waukesha engineers that certain engine components did not have service intervals that were comparable to those of other Waukesha products. The connecting rod and bearings were such items, and it was decided to design a completely new connecting rod and bearing for the 220GL.

To create the new connecting rod, the company drew upon its knowledge accumulated from designing connecting rods for other Waukesha products and utilized the latest design tools. These included Pro/E 3-D solid modeling, hydrodynamic modeling on oil film thickness and ANSYS finite element analysis. A high priority was to increase big end stiffness to decrease micro
motion from the baseline condition to historically acceptable Waukesha levels.

“We approached the connecting rod redesign using Wärtsilä’s extensive historical data on this rod, as well as our structural analysis and bearing analysis tools,” Siehoff explained. “We also collaborated with the bearing supplier, and the results are new connecting rod and bearing technologies that have gone through extensive structural and endurance testing.”

Revisions were also made to oil filtration, air starting, vibration dampening and the gas train. Other design changes were necessitated by the application of ESM, such as mounting provisions for modules, wiring and sensors.

When it comes to Waukesha’s global distribution network, Cannestra believes that the current distribution network is more than capable of handling the larger APG engines. “They’ve all
worked on our AT series engines so they’re aware of what large, two-plus megawatt types of units involve. Obviously we will offer APG-specific training at our product training center. We’ll also provide factory assistance during the initial phases to bring them along and ensure that they understand the product.”

Cannestra added, “Our distributors know gaseous-fueled engines, so this is just an extension of what we do today.”

Waukesha Engine is also investing substantially in its manufacturing infrastructure to accommodate the new APG2000 and 3000 engine generator sets. The company will soon take delivery on a multimillion-dollar vertical bridge-style milling machine, which will bring in-house the capability of machining the crankcases for the larger engines. The company has also made significant upgrades in its production test cells in order to handle the higher generation outputs of the APG engine generator sets.

“We’re continually investing in our current product and we are always trying to stay on the leading edge of manufacturing processes,” said Mike Storms, vice president of manufacturing.
“Adding new products into the mix is a catalyst for additional improvement. It becomes an opportunity to rearrange the facility, invest in additional training for our work force and add specific new equipment.”

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