| I. Alternator does not excite itself | Link L1-L11 on internal strip L1 is missing or making bad contact | Set Link L1-L11 properly. |
| Field suppression switch, if provided, did not close | Check Field suppression switch |
| Pilot exciter circuit has an interruption | Check the connection from pilot exciter to terminal strip L1, L2 and to the exciter panel |
| Residual magnetism is too low | Apply separate excitation from a 4.5 V … 12 V battery until excitation is building up; + pole of battery to L1, - pole of battery to K1 both on the terminal strip L1. (Caution: If the starting battery is used for this purpose, it should not be grounded, as the excitation circuit is already grounded on one point.) |
| Speed of prime mover not correct | Measure speed and if not correct, adjust it |
| Main exciter circuit is interrupted | Check rotating rectifiers, replace faulty cells or the complete set |
| U-diode, if included, is faulty | Disconnect U-diode, check it as any other diode in by-pass and blocking direction. If no spare diode is available, just remove diodes. (Caution: Without U-diode the rotating rectifier is not protected against over-voltages) |
| Varistor, if included, is faulty | Check visually and replace, if faulty. If no spare varistor is available, just remove it. (Caution: Without varistor there is no protection of rotating diodes against over-voltages) |
| Diodes n1 of regulators are faulty | Replace regulator |
| The relay d1 is faulty | Initiate self-excitation by means of a battery. If the alternator voltage is getting too high, interrupt connection 16-17 on regulator circuit plate. If hereafter, nominal voltage is existent at the alternator terminals, relay d1 is faulty |
| II. Alternator does not excite itself to nominal voltage | Rotating rectifiers are faulty | Check the rectifier cells one after the other, replace faulty or complete set |
| Speed of prime mover not correct | Check Speed, if necessary, re-adjust |
| III. Alternator does not excite itself at no-load to nominal voltage to break down under load | Rotating rectifiers are faulty | Check the rectifier cells one after the other, replace faulty or complete set |
| Speed breaks down | Inspect governor of diesel engine |
| IV. Alternator does not excite itself to nominal voltage; voltage is hunting between 40% and 70% of nominal voltage | The voltage measuring circuit is interrupted somewhere, e.g. the link 6-8 on L1 of the voltage reference adjuster is missing | Check the setting of all the links of strip L1 at the inside of the terminal box (refer to the connection diagram supplied with the machine), if necessary re-arrange the links |
| V. Alternator excites to an excessive voltage; manipulation on the reference voltage adjustment are of no effect | Power transistor p5 is faulty | Disconnect the lead to its base (B), if the alternator continues to excite itself too high, the transistor is faulty |
| Relay d1 does not pull up | Interrupt connection 16-17 on the regulator plate, if now nominal voltage is existent, relay d1 is faulty or the supply voltage to the relay is missing |
| Transformer m1 is faulty | Check the transformation ratio. When supplying to the transformers primaries with 110 V at terminal 1-2 of L3, 230 V at terminal 1-3 of L3, 425 V at terminal 1-4 of L3, 525 V at terminal 1-5 of L3, the secondaries should show at the conductors red/yellow 48 V, green/blue 48 V, black/grey 6 V |
| Fault in the regulator circuit plate | Replace the regulator |
| VI. Alternator voltage is hunting | Speed variation of the prime mover | The frequency variations are caused by the prime mover; check the governor of the prime mover |
| Oscillation of the regulator circuit | Oscillations in the regulator circuit may arise, if incited by the prime mover. To correct this, it is generally sufficient to reduce the capacity of condenser ky on the regulator plate, in rare and more complicated cases it might becomes necessary to alter also condenser kx and the resistor rx |
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