SHIM 1635521 - Caterpillar

Loading of the Generator
When a generator is installed or reconnected, be sure that the total current in one phase does not exceed the nameplate rating. Each phase should carry the same load. This allows the engine to work at the rated capacity. An electrical unbalance can result in an electrical overload and overheating if one phase current exceeds the nameplate amperage.Allowable combinations of unbalanced loads are shown in Illustration 1. When you operate with significant single-phase loads, the combinations of single-phase load and three-phase load may be used. Such combinations should be located below the line on the graph.
Illustration 1 g00627416
Allowable Combinations of Unbalanced Loads
Block Loading and Transient Capability
The block loading capability (transient response) of a generator set that is powered by a gas engine is less than a generator set that is powered by a diesel engine. Most of this difference is directly attributed to the inherently different fuel systems of the two engines. When the governor calls for more power, a diesel engine reacts by adding fuel directly into the cylinder. This method permits the diesel engine to accept 100% block loads with acceptable voltage dips and frequency changes. When the governor on a gas engine calls for more power the throttle opens. This causes a larger flow of the air/fuel mixture to move through the aftercooler core and the air intake manifold and into the cylinder. This time delay reduces the gas engine's capability for accepting large block loads. If a block load derating is required, refer to ISO 8528 Standards or SAE J1349 Standards.Power Factor
The power factor represents the efficiency of the load. The power factor is the ratio of apparent power to total power. This ratio is expressed as a decimal. The power factor represents the portion of the current which is doing useful work. The portion of current which is not doing useful work is absorbed in maintaining the magnetic field in motors. This current is called the reactive load. Engine power is not required to maintain the reactive load.In most applications, the power factor of the system is determined by these components: electric motors, controls and transformers. Induction motors usually have a power factor that is no larger than 0.8. Incandescent lighting is a resistive load of about 1.0 power factor, or unity. Controls can operate at any power factor. Drivers that have variable frequency or variable speed can operate at any power factor. An uninterruptible power supply can operate at any power factor. In this case, the power factor can be between 0.4 and 1.0. The power factor of a system may be measured with a power factor meter or determined by calculations. Determine the power requirement in kW by multiplying the power factor by the kVA that is supplied to the system. As the power factor increases, the total current that is supplied to a constant power demand will decrease. With equal loads, a lower power factor will draw more current. A high power factor will result in full engine