PLATE 4N4107 - Caterpillar

Check the wiring.
Stop the generator set.
Check the wiring.Expected Result: The wiring is correct.Results:
OK: Go to Step 2.
NOT OK: The erroneous regulation may be observed if the CT polarity or PT polarity is incorrect. Reverse the polarity. See the proper wiring diagram for details. Refer to Testing And Adjusting, "Wiring Diagrams". STOP.
Check the parameter values.
Start the generator set and load with 25% to 50% of rated load. Use 0.8 power factor inductive load, if at all possible.
Check the values in parameters :04 and :05.Note: Parameter :52 (current) provides the measured value of the current in the "B" phase only.
Measure the ampere load on the "B" phase.
Measure the signal voltage level at regulator terminals 5 and 6.
Verify that it is in correct proportion to load amperes and agrees with the settings of parameters :04 and :05.Expected Result: Any parameters show negative numbers.Results:
OK: If any parameters show negative numbers, a CT or PT polarity is incorrect or the phase rotation is wrong. Verify the polarity and the rotation. STOP.
NOT OK: Go to Step 3.
Check the parameter values (continued).
Check the value in parameter :52.Expected Result: Parameter :52 reads less than the actual generator current, which was measured by another meter.Results:
OK: Parameter :52 reads less than the actual generator current, which was measured by another meter. Slowly decrease parameter :05 until the currents match.
NOT OK: Parameter :52 reads more than the actual generator current which is measured by another meter. Slowly increase parameter :05 until the currents match.
Check the parameter values (continued).
On units with part numbers of 130-xxxx and older, check the value in parameter :16 and :17. Some combinations of gain parameters :16 and :17 may cause unstable operation. Try the default settings.
On units with part numbers of 155-xxxx and newer, check the value in parameters :36 and :37. Some combinations of Gain parameters :36 and :37 may cause unstable operation. Try the default settings.
If the problem only exists at low power levels, check the value in parameter :38. Try raising the value. This is not valid for the earlier digital voltage regulator, which does not have parameter :38.Expected Result: The problem has been resolved.Results:
OK: The problem has been resolved. STOP.
NOT OK: The problem has not been resolved. Go to Step 5.
Verify the CT sizing.
Remove the remote PF/KVAR adjust rheostat.
Retry the operation of the generator set.Expected Result: The problem has been resolved.Results:
OK: The problem has been resolved. STOP.
NOT OK: The problem has not been resolved. Verify the CT sizing. The digital voltage regulator is sensitive to the CT sizing. The droop current transformer should be sized to provide no more than 5 VAC (RMS) at full rated load but not less than 3.5 VAC either. Proper sizing will significantly aid the accuracy at lower power levels. Go to Step 6.
Check the generator set.
Turn the engine off.
Disconnect all accessory wiring from terminals 3, 5, 6, 7, 40, 41, 42, 43, 44, 45, and 50. Remove the serial data link, if installed.
Start the generator set and operate at "No Load".Expected Result: The generator set