SEAL ASSEM. 3G3752 - 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. If one phase current exceeds the nameplate amperage, an electrical unbalance can result in an electrical overload and overheating .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 LoadsBlock Loading
Block loading is the instantaneous application of an electrical load to a generator set. This load may be anywhere from a moderate percentage of the rated load up to the rated load.The block loading capability of a generator set depends on the following factors.
Engine transient response
Voltage regulator response
Type of the voltage regulator
Altitude of operation of the generator set
Type of load
Percent of load before the block load is appliedIf derating for the block load is required, refer to ISO 3046 Standards or SAE J1349 Standards. Also, reference Engine Data Sheet, LEKX4066, "Loading Transient Response" and Engine Data Sheet, LEKX4067, "Block and Transient Response". Note: ISO stands for International Standards Organization.Power Factor
The power factor represents the efficiency of the load. Power factor is the ratio of apparent power to total power. The power factor is expressed as a decimal. The power factor represents that 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 or other devices.In most applications, electric motors and transformers determine the power factor of the system. Induction motors usually have a 0.8 or smaller power factor. Incandescent lighting is a resistive load of about 1.0 power factor, or unity.The power factor of a system may be determined by a power factor meter or 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 supplied to a constant power demand will decrease. For example, a 100 kW load at a 0.8 power factor will draw more current than a 100 kW load at 0.9 power factor. High power factor will result in full engine load at less than the rated amperage of the generator. A lower power factor increases the possibility of overloading the generator.Note: Caterpillar generators are designed for a 0.8 power factor unless otherwise specified.Excitation Systems
Self-Excited Generators
Self-excited (SE) generators receive power for excitation and voltage sensing for the regulator from the output of the main armature of the generator. The voltage regulator senses the generator output voltage. The voltage regulator provides the regulated output to the exciter of the generator. The exciter then provides power to the main rotating field. As the main field rotates, a voltage is induced into the main