New 150, 180 and 200 kW units all powered by same 10.3 L engine
By Mike Brezonick
Along with its large KD generator sets, Kohler Co. is also launching a trio of new gaseous-fuel generator sets for standby power service in industrial, commercial and residential applications. The new 150, 180 and 200 kW gen-sets are designed to provide high power density and a more compact and lightweight footprint than the company’s existing units, which can be a significant advantage in the market according to Amy Haese, product manager, industrial gas generators at Kohler.
“We do sell a lot of units where footprint can be extremely important, whether they’re on a roof, in a parking lot or within a building,” Haese said. “So being able to get that smallest footprint helps with the flexibility, mounting and space in their facilities.”
Much of the size difference is based on the use of a new engine. The existing 150, 180 and 200 kW units incorporate 8.8 and 11.1 L engines, while the new units will be driven by Kohler-designed engines built to the company’s specifications by a U.S. company. The engine is 10.3 L, V8 that incorporates a Kohler-designed intake manifold, exhaust system and oil thermostat assembly. The front-end accessory drive includes a decoupled fan drive that allows the fan and water pump to operate at different speeds.
The engine and overall generator package are more compact and more than 1000 lb. lighter than the existing units.
“Most of that is coming from the engine,” Haese said, “but by having a smaller engine that does allow us to save space on the supporting structures. The skid and the enclosure are smaller too, which means we’re able to reduce that package size and weight.”
Single engine benefits
Along with the space and weight savings, the single engine displacement across the three gen-sets results in improved manufacturing efficiencies and parts commonality across the range, which helps both Kohler and the end customer, Haese said. “Right now, we’ve got two different engines, which are two different platforms the customer has to learn,” she said. “Now it’s the same Kohler engine from 150 to 200, which makes it easier.”
The engine drives Kohler-built four-pole, rotating field permanent magnet alternators that incorporate Kohler’s Fast-Response permanent magnet excitation system designed to deliver excellent voltage response and short circuit capability of up to 300% of the rated current for as long as 10 seconds.
Engine and generator functions are controlled through either of two digital controllers, both built by Kohler. The APM402 provides metering, control and diagnostic functions, as well as event logging, voltage regulation, alternator overload protection and audible and visual alarms for shutdown and warning faults. It incorporates one analog and three digital inputs and Supports Modbus RTU, Modbus TCP and SNMP version 1 protocols.
The Kohler APM603 controller provides similar metering, control and diagnostic capabilities, but adds more precise voltage regulation, more inputs and outputs and can be used to parallel as many as eight generator sets, with load sharing and first-on control logic.
“Both of them are available across the line,” Haese said. “Depending on what the customer needs, the APM603 does offer quite a few advantages. You can parallel gen-sets, it has better voltage regulation — you get 0.25% on the APM603 versus or 0.5% on the APM402 — and it has a larger, 7 in. display. It all comes down to how much functionality and how big a display that the individual purchaser wants.”
Dual Fuel System
Other key features of the new gen-sets include a patent-pending dual-fuel system, a specially designed fuel connection that reduces fuel pressure drop.
The dual fuel system enables the gen-set to switch from the primary fuel to a secondary fuel automatically in specific situations. “If the natural gas supply is lost, it will automatically go to LP without shutting down,” Haese said. “Then the unit will recognize if LP is low and will look to see if natural gas has returned and will automatically switch back. There is also a switch on the reset box on top of the junction box that allows the user to switch from one fuel to the other and it will do it without shutting the gen-set down.”
The fuel connection incorporates a 2 in. NPT pipe plumbed through the skid wall to connect the fuel to the gen-set, along with an oil drain connection. A special fuel system transition built into the skid is intended to reduce fuel pressure drop. “We created a skid-mounted fuel inlet to the engine,” Haese said. “We used CFD and FEA to create an inlet that significantly reduces pressure drop, which helps in large transient load steps.”
The engine and generator are packaged in a Kohler-designed enclosure that includes a rear louver, an optimized intake baffle designed to improve airflow and acoustics and a range of electrical options, such as enclosure heaters, damper actuators and LED lighting.
The new gen-sets will be available in 60 and 50 Hz versions and will be available at the end of the third quarter, the company said.
This story originally appeared in the August issue of Diesel Progress. For a free subscription, click here.