A generator rating is a pre-defined evaluation aimed at a particular generator model by its own manufacturers. This means that they should be able to precisely predict the power outlet, the generator is capable of producing. These ratings are a powerful tool in your buying guide when you go out for generator shopping. By being aware of the ratings of a generator you can evaluate it with your own power needs and requirements and make an informed decision.
These ratings also point towards the pivotal differences between different manufacturing companies and the generators they manufacture. It is later proved how accurate these ratings are.
Certain parameters are usually published by manufacturers, these are used to determine the size of load both in kW and kVA, maximum permissible voltage, service expected of the generator, etc. One common question that arises by people is that why generator rating in KVA is presented everywhere instead of KW?
Generators are generally rated in kilo Volt Amperes (KVA), this practice is applied to almost all energy supplying equipment. The main difference between kilo volt-amperes and kilowatts is that kilowatts represent the actual power of a generator while kilo volt-amperes represent its supposed power and output.
A generator’s power factor depends on the load of the devices that are attached to it, so it is practically not possible to correctly anticipate its real power. This power is hence, always approximately calculated.
Generator Rating Calculation:
The full load current of a generator is calculated in this way: I= 1000 x S / V . Now S represents the generator rating in kilo volt-amperes and V equals the generator rated voltage in Volt.
Not knowing how to calculate in kilovolt amperes can be really frustrating sometimes, with our generator rating formula, this problem can be solved for you.
Different capacity generators have different calculations from Watts to Amperes. For example, a 3000-watt generator, its allowable load power is 0.8 the current, then, can be calculated as
I = 3000 / (120 x 0.8) = 31.25 A (Amperes)
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KVA Rating chart:
Creating a cut sheet information is normally comprised of kW, KVA, Frequency, Voltage, and phase of the generators. Granted, this is the standard requirement of any project, yet it is not the only thing that determines its exact size. For further parameters that would facilitate engineers to determine the load size precisely, major manufacture companies now provide different Apps that prove really helpful in this regard. For more general information a generator rating chart is provided below.
There is a standard rule of generator power output calculation. Nearly all companies rate the generator output in Watts or kilowatts. Now the general formula for this is watts = Volts x Amps. For example, if you purchase a 5 kW generator, the output it provides will be 41.67 amps.
Generator rated Voltage:
A generator’s Voltage rating is usually described as the operating voltage between two of its 3 terminals meaning it is the phase to phase voltage. Small or medium-sized generators’ rated voltage is generally one of a list of standard voltages whereas for large generators it is selected at a level fitted for fiscal and efficient generator design. The rated voltages range is more or less:
- 4000 to 14000 V for small generators
- 12000 to 2000 V for medium generators
- 14000 to 28000 V for large generators
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Standby Generator Ratings:
The home standby generators are usually more expensive and their installation is also expensive as they are not like normal generators to be installed by just about anyone, rather an experienced electrician is required to install them properly, hence the labor cost of that should also be considered in the total cost of a standby generator.
Certain elements are a must to understand while choosing the right ratings.
- The average load factor
- Will the generator be running independently or alongside a utility
- The maximum required load
- The approximate hours per year that the generator will be running
These generators usually provide more power and tend to provide electricity for almost all the appliances of a standard household. One more feature is that these generators mostly come with an automatic switch and can start automatically when the power goes out. The best feature (arguably) is the one that runs a self-diagnosis every once in a while and it informs you promptly if maintenance is needed. Their range is approximately 5000 to 20000 watts.