GUARD 7V3791 - Caterpillar

All Caterpillar Generator SetsA new generation of automatic voltage regulators (VR3) is gradually being phased into production on all Caterpillar SR-4 Generators. See Illustration 1. These VR3 regulators will standardize the product, offer a better value, and improve reliability.
The VR3 Regulator is a completely sealed electronic module. The design is similar to the Caterpillar electronic speed switch. One part of the black lexan box contains the electronics and the other part forms the heat sink for the high power components. This configuration reduces the number of high power and regulator parts, and offers less exposure to the atmosphere. See Illustration 2.
Illustration 1. View of the complete VR3 Regulator.
Illustration 2. Top and bottom parts opened up in a VR3 Regulator.The VR3 is mounted on the left side of the generator terminal box instead of the center location for the former regulator. See Illustration 3. Remove the side panel from the terminal box to adjust the potentiometers for voltage level and gain.
Illustration 3. Location of the VR3 Regulator.The paralleling feature (droop current transformer) is becoming an option on all generators with VR3 Regulators.
For operation and troubleshooting, study the new VR3 Voltage Regulator Supplement, SENR3473, for the generator set Service Manual. Individual parts of this regulator are not presently serviced.