Starter - Exciter circuits for a 12kw BDC Generator

[Murphy99]

I have the honour to recomission this "old gentleman" a Petter Waushaka Single Phase 110/220Volt 60hz, 63 amps.
Inspected the brushes, commutator and sliprings - good shape. Blew the dust off. Hooked up 24volt battery (correct Polarity)and loadbank. Pressed the START. The Generator cranks the engine. It starts. Ramps to 1800. Select Load ON. Voltage goes to 243. Current 3 amps. Increase load to 10 amps. Freq drops to 58. Fiddle with governor linkage. 60 Hz. 240V. Increase load to 20 amps. Governor does not respond. Freq drops to 55.Fiddled the linkage again. Volts drop to 10. Shutdown. Restarted several times nothing more than 10V. Nameplate has Excitation volts 60 VDC. I guess this is a "wound rotor". Acts as a DC Motor to start. By magic ...some RPM stops cranking and reconfigures to alternator (Select ON OFF ON). Under the exciter coils ther is a DIODE Bridge (to get the 60VDC??)and 2 wire wound resisters.
Need a schematic to identify a voltae regulator to begin troubleshooting the DC. Still have 10VAC, little current independent of load.
Anybody know of a web accessible schematic to begin troubleshooting?
TIA

 

[jbartos]

Suggestion: Surf web for Generator Service Firms that have been in business for long time. They may have a schematic available. E.g. visit

http://wholesale.superpages.com/b2b/C-Electric+Motor+&+Generators/S-TN/T-Knoxville/

http://wholesale.superpages.com/b2b/C-Electric+Motor+&+Generators/S-CT/T-/

etc. for more info