Your Project Reference:

1. Electrical and Power Output

System voltage is the nominal voltage for the generator. For example, the 24-volt unit will have an adjustable range of 22 to 34 Vdc.

Polar's generator power ratings are based on continues duty operation. Examining the average current demand and the peak current demand of the load verses the battery bank size will provide information on generator cycling required engine start response, adequacy of generator size.

Grounding can be your worst nightmare if not properly chosen. Most applications require the engine, alternator, and enclosure all tied to the same ground. Some applications require that the ground is positive polarity. Polar can provide either positive or negative grounding. Changing from a negative to positive (and visa versa) ground in the field is not practical from experience.

2. Number of Generators on Site.
The following factors should determine the choice of using one or two generators on site: requirement for reliability, access to site, runtime between site visits, annual run time, prime power verses standby, available on-site maintenance, and fuel type.

The generator (no matter who manufactures it) will fail at some point in time. Maintenance is a contributing factor to reliability; it has been our experience that operators typically provide poor (preventive) maintenance.

Travel cost to the site during bad weather is an economic factor to consider. One or two emergency visits to a site could exceed the cost of a second generator.

Prime power sites should have two generators. High reliability sites using propane should have two generators on site. Standby sites using propane, which have convenient access can use a single generator.

3. Genset Location on Site.
For cold climates (minus 60° F to 15° F) (minus 50° C to minus 10° C) we recommend that the generators are installed inside the shelter. Polar does build enclosures, which are suitable for cold climates, but the problem is with servicing the generators during very cold weather. With an enclosure external to the shelter, the only practical method of service is to place a tent around the generator or pull the unit off its site and replace it with a spare unit or servicing it inside a truck.

4. Site Location and Ambient Conditions.
An accurate response to ambient conditions provides a confirmation of enclosure style and required accessories.

Altitude is important information because it determines the amount of engine de-ration (3.5 % per 1000 feet).  Location provides us with an idea of fuel supply, salt fog condition, insect fouling, etc.

5. Operation.
The number of calculated or expected run hours between service calls for either standby, prime or hybrid power .   The number of operational hours during the month of heaviest usage and the total hours expected in a year .   This helps us confirm that the right engine was selected with the proper accessories and monitoring.

6. Fuel.
Specifying the fuel helps us to confirm that the right engine and fuel system was selected. Propane can be drawn from the tank as either a liquid or gas. Liquid withdraw is recommended for cold climates (below 15° F or minus 10° C).

Most of the problems we have seen for Telecommunications applications involve the selection of the wrong fuel and engine type for their site or application. Propane appears to be the fuel of choice because of the simpler site permitting process and the fact that it’s a cleaner burning fuel. Some argue that propane is a better fuel in cold climates because it does not have the low viscosity and waxing problems of diesel fuel and that spark machines are easier to start. In actual practice a diesel engine offers more reliable starting in cold weather, and in areas which have wide temperature swings diesel is also lower in maintenance. The problem with propane engines is vaporizing the liquid fuel and the load valve adjustments which are subject to temperature swings. Until a computerized propane carburetor is available, diesel is the preferred choice for reliability in cold weather.

Polar has developed a number of accessories to help offset the propane fuel problems and we are continuing developmental efforts to improve the operation of propane engines.

7. Enclosure Style.

Use an open frame assembly when installing inside a shelter, this provides ready access to maintenance and inspection. There can be cooling problems installing an enclosed generator inside a shelter.

Acoustic noise control is one factor in selecting an enclosure style. Weather and engine type are the other factors influencing enclosure style.

What is your noise requirement dBA at meters.

8. Engine Style

There are pro’s and con’s regarding the selection of air-cooled verses water-cooled engines. 

Water-cooled engines are preferred for operation within the shelter even in cold climates. 

PROS:	Water cooled engines have lower acoustic noise. Easier to channel heat away from the engine and out the enclosure. Oil operates at lower temperatures. More efficient combustion in locations where there are wide temperature fluctuations.
CONS:	Increased maintenance due to water pump and fluid. Increased engine purchase cost.

Air-cooled engines are preferred in very cold climates because there is no fluid to freeze or in standby operation which see seldom use. 

PROS:	Simpler to maintain. Lower in purchase cost. Smaller horsepower units (under 15 Hp) are more compact.
CONS:	Greater acoustic noise. The oil levels and oil changes are more critical due to the higher operational temperatures. Harder to collect heat off engine and expel from enclosure.

9. Air Conditioning.

Providing belt driven air conditioning to prime power sites that require cooling provide a significant advantage over inverter driven or AC generators powering the air conditioner. See the Airgen product for more details.

10. Remote Control and Monitoring.

Remote communications to the genset is the most important feature that can assist maintenance. Being able to see the: engine RPM, oil pressure and temperature, ambient air temperature, fuel pressure, voltage and current outputs, run time, alarm status, etc., will prepare the technician with the right tools and spare parts for the site visit. Some of the alarm conditions can be cleared remotely saving a trip to the site. This accessory requires either a land or wireless line. Since the generator is typically the last item planned for the site, getting the extra communication line is difficult.

11. Miscellaneous Options.

Notes.