FAQ

Questtions on mechanical malfunctions:

>> Heavy vibrations of the machine
>> Too high temperature of the bearing
>> Bearing noise
>> Corrugation during standstill

Questions on common electrical malfunctions:

>> Alternator has no excitation

Electrical malfunctions of the control unit:

>> Output voltage is too low
>> Output voltage is too high
>> Output voltage varies
>> Instable parallel operation (static mode)
>> Instable parallel operation (power factor controller)
Leerzeile
Leerzeile
Heavy vibrations of the machine
Unbalanced parts mounted on the shaft end (flywheel, belt drive)
  • Dismount parts, re-balancing, balancing of all parts together by means of stroboscopic method.

Alignment not precise
  • Check alignment, readjust clutch

System operates at resonance
  • Measure vibrations over speed, draw resonance curve
  • Change elastic mounts
  • Change actuators.
  • Stiffen foundation.
  • Consultate Hitzinger

Bearings defect.
  • Check running-noise of the bearing; SPM measureing , change bearings

Vibration of prime mover too high
  • Check elastic mounts, reduce vibration of actuating machine
Bearing temperature is too high
Too much grease inside the bearing
  • Just regrease prescribed quantity
  • Temperature lowers by itselfes
  • Set grease outflow ducts free of old grease
  • If necessary dismount bearing cover and remove surplus grease.
No grease inside bearing
  • Regrease bearing (prescribed quantity) and take a close look if bearing works properly, otherwise exchange bearing.
Bearing load is too high
  • Check radial and axial forces (by belt drive or turbine runner)
  • Rücksprache mit Werk.
Tension of the bearing
  • Check the alignment.
  • Consultate Hitzinger.
Bearing noise
Bearing is damaged (e.g. by transport)
  • Remove bearing and let it be analyzed
Contaminations in grease
  • Wash out bearings, renew grease, if necessary exchange bearings.
Bearings run dry
  • Regrease bearings.
Corrugation during standstill
Vibration from ouside are transferred to the bearing
  • Isolate machine from outer vibrations.
Alternator has no excitaion
Speed too low
  • Raise speed to nominal speed
No or too low remanence voltage for self excitation.
  • Measure remanence voltage
  • Standard value at nominal speed phase to hase is 10% of nominal voltage
  • If remanence voltage is lower than 10% - then shock excitation is necessary
Shock excitation:
  • Disconnect AVR
  • Accelerate alternator to nominal speed
  • Take a 4.5V torch battery and connect the auxiliary voltage to the field of the exciter. Take care of the polarity – check wiring diagram (terminal 6 pos / terminal 14 neg)

When output voltage rises disconnect battery immediateley, otherwise battery can explode !

Short circuit or too high load of the alternator
  • Check wiring, disconnect load
AVR fuse defect or bad contacts
  • Check fuse and contacts of the fuse holder. The fuse of the T21 AVR is directly at the PCB, the T17 AVR the fuse is in the lead-in wire of the auxiliary winding. (see wiring diagram)
If those actions show no success, a foreign excitation is senseful, so the malfunction can be found faster. Following steps have to be done:

Foreign excitation:
  • Disconnect lead in wires of the exciter field at the terminal bar of the AVR
  • Connect an external, potential free and adjustable DC source to the exciter field. Therefore you can use a 12V car battery in combination with a resistor or a adjustable transformer and a rectifier bridge.
  • It is very important to have the right poalrity - check wiring diagram (terminal 6 pos / terminal 14 neg)
  • Accelerate alternator to nominal speed and excite with 20%-30% of the nominal exciter current wich is stated at the rating plate. So app. the nominal voltage must be achieved. The voltage of the auxiliary winding (see wiring diagram) shall be about 100 V.
  • Watch alternator voltage! – do not adjust a too high voltage!
  • If more than 30% of the nominal exciter current is needed or when the output voltage does not rise at all so the failure is in the alternator itslef. Error diagnosis according to the following steps for rotating rectifier bridge, overvoltage arrestor, polewheel , auxiliary winding and exciter field.
  • If excitation current and voltage at the auxiliary winding are correct, the failure is located in the voltage regulator.

When foreign excitation is used, all electrical and mechanical safety regulations have to be obeyed. All consumers and sensitive devices ave to be switched off because of the possibility of voltage peaks!

Rotating rectifier defect
  • Disconnect rectifier and measure.
Overvoltage arrestor defect
  • Disconnect Overvoltage arrestor and measure.
Exciter rotor defect
  • Measure resistance of all three windings. Values have to be symmetric. Reference value lower than 0.1 Ohms – measure isolation value.
Polewheel or connection to rectifier defect.
  • Disconnect connectros of the polewheel to the rectifier and measure the resistance
  • Reference value 0.5 to 2 Ohm, depending on the type of the alternator. – measure isolation value.
Auxiliary winding or wiring defect.
  • Disconnect the polewheel of the exciter field from the AVR (see wiring diagramm), measure the resistance.
  • Reference value 4 to 10 Ohm, depending on the type of the alternator.
  • • Measure isolation value against earth.
Exciter field or wiring defect.
  • Disconnect exciter field from the AVR (see wiring diagram), measure resistance
  • Reference value 4 to 10 Ohm, depending on the type of the alternator

    • Measure isolation value against earth.
Resistance measuring only when machine absolutely stands still.
Isolation value measuring only when electrical and electronical devices are disconnected!
Output voltage is too low
Speed is too low
  • Raise speed to nominal speed.
Voltage reference value is set too low
  • Adjust potentiometer to nominal value.
Frequency in the area out of control area
  • Raise speed to nominal speed.
Power factor regulator active in isolated
  • Bridge control input from the PFR and disconnect signal line to the AVR.
Malfunction in the exciter system of the machine
  • Error location as ("Alternator has no excitation").
AVR defect
  • Exchange automatic voltage regulator.
Output voltage is too high
Cut off of the measurement circle
  • Measure alternator voltage at the AVR terminals (see wiring diagrams), remove cut off.
Voltage reference value is set too high
  • Adjust potentiometer to nominal value.
Cut off of the circle of current transformer for parallel operation
  • Check current transformer and lines and change if necessary.
Cut off of the circle of reference values
  • Check potentiometers and lines.
Leistungsfaktorregler im Inselbetrieb aktiviert
  • Steuereingang am Leistungsfaktorregler brücken, Signalleitung zum Spannungsregler abklemmen.
AVR defect
  • Exchange automatic voltage regulator.
Output voltage varies
Supply of the AVR has a worng phase position to measurement voltage
  • Exchange connections of the AVR supply (auxiliary winding)
Prime mover instable (eg. torsional vibrations)
  • Stabilize prime mover or change it.
Resonance between AVR and load (eg. Controlle drectifier, light-controller etc.)
  • Change time constant if the AVR or of the load regulator
  • Consultate Hitzinger
AVR defect
  • Exchange automatic voltage regulator.
Instable parallel operation (static mode)
No current transformer (static) built in
  • Integrate current transformer and adkust static.
Static upside down
  • Exchange connections of the current transformer (see wiring diagram).
Static value too low
  • Raise static vaue with the potentiometer.
Fluctuation of mains voltage too high
  • Improve mains condition or use PFR
Instable parallel operation (with PFR)
Power factor regulator not activatedv
  • Check wiring and control.
Zhase position between voltage- and current signal is the wrong way around
  • Check wiring and change signal lines.
PFR defect
  • Change PFR.