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Polar Power DC Gensets
 Polar's
6 KW genset
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.
Technical Information from Polar DC Marine:
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Polar Power, Inc. first
tested its DC generator using its PMHH Alternator technology in 1992.
Since then numerous organizations have performed extensive testing on
our generators, including the US Army. Polar’s DC generator sets (gensets)
meets both Military and Belcore power applications. Test reports are
available.
Polar assembles the
genset to meet its' clients requirements by adding the appropriate
diesel, gasoline, or gas (propane, butane, natural) engine to our DC
alternators. The engines are available in either a liquid or air-cooled
version. Polar has designed this DC alternator incorporating
state-of-the-art technologies and all new tooling to meet the increased
performance demand for:
Polar Power has met these
performance goals through an integrated engineering effort involving
detailed analysis of engine, voltage regulator, field coil, magnet,
stator, rotor, and diode effects on the system's output voltage and
current.
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Low
Maintenance and High Reliability
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The unique alternator design allows us
to turn the engine at low speeds, thereby extending engine life.
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The voltage regulator has automatic two
step engine speed control. At high electrical load demands the
regulator, through an external solenoid, automatically increases
engine RPM; at low loads the engine speed is automatically
decreased.
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Polar Power's PMHH alternator has no:
bearings, couplings, brushes, slip rings, nor rotating fields. There
are no alternator parts to wear.
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The entire alternator assembly is vacuum
dipped and baked with a polyester coating. This seals off all metal
surfaces from corrosion. Resistance to salt fog is extremely high.
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There are no electronic parts (diodes,
etc.) nor electrical connections inside the alternator. There is
nothing to short or vibrate loose inside the alternator.
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The alternator is almost impossible to
damage electrically. The outputs can be shorted for minutes without
damage.
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The alternator is thermally protected; a
sensor on the yoke can warn the operator of a high temperature
condition. If no action is taken the regulator automatically reduces
the output current so the alternator can run cooler.
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The output current is monitored by the
voltage regulator through a current transducer. The voltage
regulator has an adjustable current limit on the output. It is
virtually impossible to overload the alternator.
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Polar Power's PMHH alternator should
have an MTBF exceeding 100,000 hours. The diode bridge set is remote
from the alternator and mounted on a large heat sink to keep cool.
The voltage regulator has lightning and surge protection on both the
input and output. All the electronic components within the voltage
regulator are operated at less than 50% of their rated values.
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The only normal wear the alternator
experiences is the abrasion caused by the air being circulated
around the stator coil and this effect is limited. Polar Power's
PMHH alternator, because of its high efficiency, does not require a
cooling fan. Air moved over the stator due to rotor effect is of low
velocity. This is advantageous in sandy and dusty environments.
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The engine is protected against:
over-temperature, low oil pressure, over-speed, and over-cranking
(during starting). There is a lockout protecting the engine against
starter motor actuation while the engine is running.
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Two stage cyclone air filters are used
on the engines air intake in order to minimize the air media
cartridge replacement.
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The alternator's rotor is dynamically
balanced to improve the engine's bearing life.
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Fuel is filtered to stringent standards
for water and particle separation before entering the engine.
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Low EMI emissions are designed into the
system. There are no brushes or slip rings. Field coil is isolated
from the buss through fast diodes and capacitance. The voltage
regulator does not strobe the field coil on and off. Proportional
control reduces the back EMF produced by the field coil. The fuel
stop and two speed solenoids are attenuated for voltage spikes as a
result of turning on and off the solenoids field coil.
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Low Fuel Consumption
The PMHH alternator has
an efficiency of between 75 to 85% versus 55 to 70% for other DC
alternators. The voltage regulators' two speed engine control can save
up to 30% in fuel under light electrical loads.
Low Acoustic Noise
Improving alternator
efficiency reduces the horsepower demand on the engine which reduces the
engine noise. Eliminating the brushes, slip rings, and fan from the
alternator reduces alternator noise.
High and Low Ambient Operation
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During starting the regulator keeps the
field current off. This feature coupled with the small light weight
rotor provides a minimal load on the starter motor.
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For low ambient temperatures (-40° to
10° F) cold starting aids are available.
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Automatic two speed operation controlled
by the voltage regulator keeps the oil warm in low ambient
temperatures (reduces moisture contamination of the oil) and keeps
the oil cooler in high ambient temperatures.
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The higher alternator efficiency allows
the engine to run cooler in high ambient temperatures. The increased
alternator efficiency reduces the mechanical load on the engine
which then reduces the engines cooling requirement.
System Advantages
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No isolation relays
are required. The voltage regulator and the 6 phase diode bridge
isolates both the field coil and stator from placing a drain on the
battery during the off state.
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No warm-up relays and
timers are required. After the set is started the engine remains in
low speed operation with low power output until the engine warms up
causing a thermostat to switch on the voltage regulator. When the
engine is warm it will adjust itself to meet the required load
demand. If required, this feature can be removed.
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Alternator System
Condition Signals. The standard voltage regulator will provide the
following alarm conditions:
a. Over-current
b. Over-temperature (stator)
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Output currents and
voltages are independently adjustable. Regulator will provide
current output signal.
Options
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Air Conditioning. The
genset can conveniently support a 6,000 to 36,000 BTU air
conditioning system without effecting the 6 kW output. Polar Power
assembles a belt-driven automotive style compressor onto the engine.
An electric clutch brings the air conditioning on line when
required; when not required, there is no parasitic load on the
engine.
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Engine Styles.
a. Diesel Engine: either air-cooled or water-cooled.
b. Gasoline Engine: either air-cooled or water-cooled.
c. Gas Powered: Propane, Natural gas, either air-cooled or
water-cooled.
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Automatic Temperature
Compensation Module. The genset output, if used for charging
batteries, can be temperature compensated for superior battery
charging. A temperature sensor is placed on the battery which causes
the regulator to adjust the output voltage to match the battery
needs.
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Automatic three step
charging circuit consisting of bulk rate, overcharge (equalize), and
float. This module includes temperature compensation and automatic
start-up and shut-down (available mid 1993).
Polar’s DC generators are more expensive to purchase
than AC generators because:
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We
are using 12 Neodymium Iron Boron magnets in each alternator;
magnets add considerable material and labor cost. Most AC
generators do not use magnets. Magnets increase efficiency and
reduce generator size and weight.
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Our
alternators uses a high frequency design (360Hz) that reduces
weight, size, and greatly improves the quality of electrical power.
The high frequency design requires more labor to wind the stator.
Typical AC generators are only 50 or 60 Hz.
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The
stator has a 6-phase design to also improve electrical quality and
the torque ripple on the engine for better fuel economy. The 6-phase
design requires more labor to wind the stator. Standard AC
generators are only single or three phase.
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The
Polar’s DC generator set is optimized to produce a high current, low
voltage power output for charging batteries and powering DC loads
directly. The AC generator is optimized for a high voltage, low
current output and requires an external power supply or battery
charger to convert AC into DC. The low voltage, heavy current
windings are more expensive to wind.
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Polar’s DC generator is very corrosion resistant. We make extensive
use of stainless steel fasteners and coated aluminum materials.
Certain components must be constructed of steel due the magnetic
properties; here we coat with high temperature coatings and/or
Cadmium (CAD) plating. Corrosion resistance is important for
installations in marine or humid environments or exposed to
agricultural and garden chemicals. This construction is not typical
of AC generators.
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Polar uses the very best magnetic wire in an HML grade for a class H
rating. This facilitates long life in warm or dusty climates.
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Above the Waterline
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That's good for your environment!
or telephone
805 455 8444