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DC vs. AC COMPARISON

POLAR DC GENSET / INVERTER COMPARISON TO AC GENSET / CHARGER:

1.  POLAR DC gensets run less time than an AC genset.    

DC gensets charge batteries faster than AC gensets.    DC Gensets have enormous battery charging capablities.   An AC genset battery charging capacity is limited to the power output of the charger circuit of the inverter/charger, typically about 1200 watts.   Polar power's smallest genset has 6,000 watts of battery charging capability,  5 times faster.   

2.  POLAR DC gensets can operate at any rpm to match the load.    

An AC genset must operate at a fixed rpm, either 1800 or 3600 rpm,  to generate the required AC frequency. 

3.   POLAR DC Gensets are more fuel efficient.  

If a small load is applied to a DC genset, it will run at only the necessary rpm to power that load.    An AC genset runs at a high fixed rpm.

At full load a DC genset runs at the rpm that corresponds to highest efficiency of the engine.   An AC genset runs at a high fixed rpm. 

Overall efficiency of a Polar DC genset is between 75 and 85%.   An AC genset's efficiency varies between 10% and 75%, depending on load and brand.   

Some  Polar DC Genset applications use half the fuel of a comparable AC genset.  

4.  POLAR DC Gensets can be sized smaller than AC gensets for the same application.  

AC gensets must be sized for the peak load which occurs a small percentage of the time, usually startup loads of heavy duty motors.   Because an AC genset is oversized for normal operation, the AC Gensets diesel motor runs at high rpm with little load.

Peak operating power is determined by the size of the inverter on a DC genset system. 

A larger inverter is a lot lighter than a larger genset.  

5.   POLAR DC Gensets are quieter than AC Gensets.   

Lower rpms make less noise.

The Diesel engine of a DC gensets can be sized smaller than an AC genset and therefore quieter.    

6.   POLAR DC Gensets are lighter than AC gensets.

Because they can be sized smaller than an AC genset, they are lighter.   An AC genset typically turns at 1800 rpm.   This limits the amount of power that can be created by the engine.   A POLAR DC genset can run at a faster rpm and therefor develop more power for its weight.  

7.   POLAR DC gensets have permanent magnets and run cooler. 

An AC genset has to create the magnetic field which costs power and creates more heat.  

Natural rare earth magnets found in a DC genset provide the magnetic field naturally.

8.   POLAR DC gensets are more reliable and require lower maintenance than AC gensets.

Polar DC gensets are made for the marine environment, with extensive use of corrosion resistant materials and coatings.

Corrosion is the leading cause of failure of AC gensets in marine applications.

9.  POLAR DC genset engines last longer. 

When a Polar DC genset starts it runs for a specific period of time at low rpms and minimal load while it warms up.   When an AC genset starts it immediately revs up to 1800 rpm. 

AC gensets usually run at a fixed rpm with varying load.   Alot of the time they are spinning with almost no load on them.   Diesel engines last longer if they are loaded optimally.  

Because an AC genset is harder on the motor the AC genset motor does not last as long and requires more maintenance.

10.  POLAR DC Gensets have very high quality electical output wih very little ripple, voltage spikes and dips.  

Todays modern inverter chargers provide better frequency regulation than an AC generator.   When an AC generator is loaded it slows down, fuel is applied and then it speeds up again.   Throughout this entire process the frequency and voltage of the AC wave is changing proportionately with the engine speed.

11.  POLAR DC gensets produce very low electo-magnetic interference (EMI).

Because the alternating current is rectified immediately at the diode block, there is no AC power outside of the genset and therefore very low EMI.    High amounts of EMI can cause erratic behaviour of marine electronics.  

12.  Per operating cycle a POLAR DC genset is less expensive than an AC genset. 

A Polar DC genset is an investment that pays off financially because they last longer than AC gensets.  

13.  POLAR DC Gensets are more rugged than AC gensets.

POLAR DC Gensets are more durable and reliable and will provide power when you need it the most.  

POLAR DC  gensets are rugged and hard to break and survive in the most extreme conditions of heat and cold, humidity, salt fog, sand and dust.   Whatever the environment, you can count on a POLAR DC genset.

POLAR DC gensets are built to Military standards to be used in hostile, exteme environments.    

Its impossible to overload a POLAR DC genset because internal circuitry protects the genset.   The outputs can be shorted for minutes without damage.

Polar DC gensets have more sensors and protective software than their AC counterparts.  

14.  POLAR DC Gensets can accomodate optional equipment.

You can mount a 12 volt alternator, a refrigeration or air conditioning compressor, water maker pump, a bilge pump, or a hydraulic oil pump to the front of the engine.  AC gensets do not accomodate options because the frequency of the AC waveform is affected by the startup and use of the equipment.

15.  POLAR DC Gensets are available in many different voltages.

Stock voltages include 12, 24, 28, 36, 48, 72, 84, 144, 280 and 300 DC.   Custom voltages are available.    

A POLAR POWER DC MARINE GENSET WITH INVERTER

CAN OUTPERFORM

AN AC GENSET WITH CHARGER

EVERY TIME

The only time that an AC genset can outperform a DC genset, with the same engine size, is when it is providing electricity for only one AC load, and the genset is sized to provide the exact amount of electicity for that one AC load.   I have never seen a genset on a small boat that is dedicated to only one load. 

DC gensets have the ability to respond to varying loads and to operate at peak efficiency at any load.  

Most boats demand erratic amounts of power.   Everything cycles on and off, on a boat.   One moment it is drawing 10 amps, the next it is drawing 50 amps.   DC gensets can alter there engine speed to correspond to these changes.

An Odyssey battery bank can further insulate a DC genset from erratic loads.  

POLAR DC Gensets are the most efficient diesel charging machines available today.

For more information, please type the following email address in your email program or call 805 455 8444