InnoFES Energy's Guide To Selecting your Generator
Selecting your Generator
To select the correct generator set for your application the following information will be required:
- Phases and Voltage
- Single Phase (230V) - Normally for domestic use
- Three phase (400V) - Mainly for industrial use
- Three phase (525V) - Mining industry
- Three phase (11kV) - Special applications
When determining your load requirements the following information is important:
- Size of your main breaker.
- The contents of electrical motors in your load is of utmost importance. Start-up current is normally calculated at three times the full load current of the motor for the purpose of sizing your generator.
- Determine your largest single step load. This may not exceed 50% - 60% of generator capacity on large machines and 60%-70% on smaller units.
- Determine the total load in Watts. The expected full load required may not exceed 85% of the generators full load capability.
- The following quick calculations can be used to determine estimated currents.
- Generator full load current = Gen kVA x 1.445. This current will be at 0.8PF.
- Generator full load current at unity = kVA current / 1.25
- Must the panel allow for selecting between ESKOM and generator or is the generator the only power source?
- If selection is required, must the selection be done automatically or manually?
- The selection will also determine if the generator will start automatically or manual.
The main functions of a canopy is attenuation and weather protection. With normal canopy designs, sound levels will typically be between 75dB and 85dB at 10 meters, depending on the size of the engine. Please specify for super silent canopy requirements.
- Water / coolant heater. The purpose is to prevent cold starts in cold regions.
- Dummy loads. It is essential that a diesel engine operates under at least 60% of its rated output capacity at 80% of its running time. It is harmful for diesel engines to operate under low load conditions for long periods of time.
- Fire switch
- Fuel filler pump. Manual or electrical
- Audible and visual alarms
- SMS systems. These are very powerful systems for status updates and long distance control. The possibilities are endless.
The basic characteristics of a synchronization system are:
- Any number of machines up to sixteen can be synchronised to a single load.
- The PLC will determine the load requirement over a short period of time and automatically determine the amount of machines required for the demand. The PLC will select the machine with the highest amount of hours and switch it off.
- When the demand increases, the PLC will automatically start and synchronize the required amount of machines to increase the supply.
Advantages of a synchronised system
- In cases of supply demand higher than 700kVA there is a significant cost saving on the purchase price and fuel usage.
- Due to the nature of the system, engines will rarely run under low load conditions. This will increase the life expectancy of the engines.
- Multiple machine systems have the advantage of having spare capacity when one machine is down.