SEAL-O-RING 5P8429 - Caterpillar

Regulating with Load Acceptance Module (LAM) is similar to regulating with V/Hz. LAM has more control of the frequency of the output than V/Hz. Regulating with LAM can speed up the recovery time for a block load.When a large block load is applied to a generator the engine speed temporarily decreases until the engine can produce additional power by burning more fuel. When the speed of the engine decreases, the frequency of the generator output also decreases. When the output frequency of the generator drops below a preset frequency threshold, the LAM function will reduce the voltage output from the generator. The setting on the LAM will determine the amount that the voltage will be reduced. The LAM setting can be either 13% or 25% reduced voltage. The reduction in voltage reduces the active load that is applied by approximately 25% or 50%. The voltage will remain at this level until the engine speed recovers to the nominal RPM. LAM can be used to reduce the amount and the duration of the frequency drop to the load. LAM can also allow the application of a larger load for one speed variation (turbocharged engines). Note: The frequency threshold that will trigger the LAM function is approximately 2 Hz below the rated steady state frequency of the generator. This threshold is set at the factory in order to prevent the LAM function from being triggered unnecessarily from minor fluctuations in the frequency.
Illustration 1 g01683115
Recovery of voltage from a block load with LAM and with V/Hz and without LAM
Illustration 2 g01683133
Recovery of frequency from a block load with LAM and with V/Hz and without LAM
Illustration 3 g01683134
Load shedding using LAM during a transient recovery. Note: Refer to the Testing and Adjusting section of Service Manual, KENR9009, "Knee Frequency Adjust" or Service Manual, KENR9009, "Load Acceptance Module Adjust" in order to adjust the constant V/Hz or the LAM.
Illustration 4 g01683173
When the engine RPM begins to recover from the block load, the LAM will begin to return the generator to nominal voltage gradually. This gradual return will allow the generator to return to the nominal voltage and frequency quickly. The LAM controls the rate that the generator will return to full voltage output. The rate is based on the amount of loss in frequency that was caused by the block load. A loss in frequency of less than 4 Hz from the rated frequency will allow a faster return to full voltage than a loss in frequency of greater than 4 Hz. Refer to Illustration 4.Note: The LAM should be set at 25% when block loads that exceed 70% of the rated load of the generator set are expected.