Loss Of The Desired Speed Signal During Earth Fault Test Caterpillar

Problem:

A problem can occur when paralleling an Advanced Diesel Engine Management (ADEM) II controlled electronic engine and a mechanical engine. The ADEM II Electronic Control Module (ECM) on the electronic engine may lose the desired Pulse Width Modulated (PWM) speed signal from the 167-0797 Woodward Load Share Module during an earth fault test. An earth fault can be simulated by connecting a DC light bulb or 1k ohm resistor between (+) Battery and engine block. This test is frequently done aboard ships.

Solution:

When paralleling a mechanical engine with an ADEM II controlled engine, a 131-5454 Woodward 2301A and a 167-0797 Woodward Load Share Module are commonly connected together by load share signal lines as shown in the diagram below. The load share lines are shielded. If the shield is terminated at both ends the PWM signal to the ADEM II ECM will be lost during an earth fault test. The shield should be terminated at ONLY one of the Woodward modules.

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