TROUBLESHOOTINGTESTING AND ADJUSTINGPOSSIBLE CAUSESVERIFICATION PROCEDURE35. Load Not BalancedWhen the load on the generator cables (phases) is not the samethe load is not in balance and this can cause high voltage. Sensingof the load on the generator is done from phase 1 to phase 2 andfrom phase 3 to phase 2. If the lowest load is connected fromphase 1 to phase 3, the indicated generator voltage will be high.36. Regenerative Load Power TooIn some applications the load on the generator will come from alHighinduction motor, used in lifting equipment. When a weight islowered with lifting equipment, the motor will work asgenerator. The result of this condition is regenerative power goingto the electric set. The regenerative power will cause the electricset to turn at too high rpm when:1. There is no other load, or only a small other load on the set2. When the lifting equipment has no dynamic brake.With the electric set at too high rpm the output voltage will alsobe too high.37. Open Regulator Power ResistorIf regulator power resistor (R4) is open, a temporary high voltage(R4)will be the result. This will cause fuse (F1) to open. To check (R4)disconnect wire (3) from spade terminal (3) on regulator module(A1). Check resistance from wire (3) to terminal (26). Typicalresistance is approximately 1500 ohms.38. Open Voltage Reference CircuitIf the voltage reference circuit is open, a temporary high voltagewill be the result. This will cause fuse (F1) to open. Disconnectthe voltage reference circuit by removing wires (20) and (22) fromterminals (20) and (22). Check resistance from wire (20) to wire(22). Typical resistance is approximately 95,000 ohms. Checkresistance from wire (20) to terminal (24) and from wire (22) toterminal (24). Typical resistance is approximately 65,000 ohmfor each circuit. For more information, see REGULATORMODULE.39. Lack of Load StabilityConstant changes in load can cause a condition of variable speedand voltage. Check load changes that vary at the same time.40. Too Much Vibration ofToo much vibration of suppression reactor (L1) can loosen theSuppression Reactor (L1)coil-core assembly. A loose core can prevent stability of thevoltage.41. Lack of Engine RPM StabilityWhen the voltage and engine rpm have no stability, the cause canbe either the voltage regulator assembly or the engine (governor)To find the cause, disconnect the voltage regulator assembly fromthe engine. A separate source of DC excitation is needed. Theseparate DC source can not be over 24 volts (batteries can be usedand must have a manually controlled rheostat in series with thenegative lead of the source. The rheostat is needed to giveprotection to the exciter field from too much current. Stop theengine and disconnect wires (F1) and (F2) from terminals (F1and (F2). Connect the positive cable "+" from the DC source towire (F1). Turn the series rheostat to maximum resistance lessthan five volts). Connect the negative cable "-" to wire (F2).Start the engine and run at rated rpm. Look at the AC voltmeterand turn the rheostat to add to the excitation voltage from thebatteries until the AC voltmeter gives an indication of rate,(Continued on next page)69
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