Polars 3.5 KW DC alternator has been
derived from its proven and tested 2.2 KW military generator model. The 3.5 KW
operates within 2500 to 3600 RPM; a higher speed range than
other Polar alternators, which operate in the 1200 to 3000 RPM range.
The higher speed of the 3.5 KW reduces the weight, size, and cost of
the alternator and engine.
The 3.5 KW DC generator uses Polars
Permanent Magnet Hybred Homopolar (PMHH) technology. This unique technology eliminates all
parts which typically wear or fail inside an alternator, including brushes, slip rings,
rotating fields, excitors, and bearings. The unique design also allows us to operate the
engine at viable speeds while maintaining precise voltage regulation. The six-phase stator
design reduces voltage ripple on the output and reduces filtering requirements.
The voltage regulator is unique in its ability to regulate and limit
the output current. In an over-current condition, most DC generators will either stall the
engine, overheat the alternator or engine, or trip the output circuit breaker. The most
common cause of an overcurrent load is a battery in low state of charge. Polars
generator will stay on-line without overheating, stalling, or tripping a circuit breaker.
Polar selected the Kawasaki Model FE290 to drive its alternator
because it is the best engine on the market for this application. Note the
Oil Pump - The most important criteria Polar used in the selection of
Kawasakis Model 290 was the full pressure lubrication system using an oil pump.
Unlike your automobile, most small engines do not use an oil pump. Instead, these engines
splash lubricant with the spinning crankshaft. Unfortunately, it takes a while for oil to
migrate to the bearings supporting the shaft. Using splash lubrication requires critical
maintenance for the engine oil level.
The once-a-week automatic exercise of the generator, or long periods
without operation create the need for a full pressure lubrication system.
Large 286CC Displacement - Most generator manufacturers
use a 286CC displacement engine to deliver 5 KW.
Polar derated the 286CC engine to deliver a continuously rated 3.5 KW in order to extend engine life. Engine
duration is important for sets
operating on propane and natural gas, because these fuels burn at higher temperatures, and
can burn the exhaust valves.
Low Vibration - Kawasaki has incorporated a unique reciprocating balancer
within its engine design. Typical single-cylinder engines will vibrate more than
multi-cylinder engines. Vibration causes noise and can adversely affect electronic
assemblies located near the generator. Kawasakis Model 290 produces amazingly little
vibration and noise.