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18 l Automatic Voltage Regulator – GRT7-TH4E / GRT7-TH4PE
14 PROBLEMS, CAUSES AND CORRECTIVE ACTIONS
Table 14.1
There is circulation of reactive power
between alternators when operating in
parallel.
▪ Phases sequence (R-S-T) incorrectly
connected;
▪ CT connections are inverted;
▪ Droop adjustment excessively low.
▪ Connect phase sequence correctly.
▪ Correctly polarize the CT in the phase shown
below:
▪ Increase droop adjustment, rotating trimpot
P2 clockwise (CW).
Generated voltage decreases when load is
applied, and it does not return.
▪ Dropping speed of the driving machine;
▪ Under frequency protection engaged.
▪ Correct speed regulation.
▪ Adjust Under frequency protection by rotating
trimpot P5 clockwise (CW).
Alternator voltage does not increase.
▪ Residual voltage excessively low.
▪ Inverted F+ and F- terminals.
▪ Terminals F+ and F- are inverted.
▪ With the regulator switched- on, use external
battery (12Vdc) to force excitation (*).
▪ Invert F+ and F-.
▪ Invert F (+) and F (-).
Generated voltage oscillates at no load.
▪ Dynamic not well adjusted.
▪ Alternator excitation voltage excessively
low.
▪ Adjust trimpots P3 and P4;
▪ Check the polarity of the F+ and F-
connection in relation to the generator field
cables.
▪ Insert 10Ω/100W resistor in series with field.
Voltage oscillates at a specific load point.
▪ Third harmonic of the auxiliary coil is
high.
▪ Eliminate auxiliary coil and proceed with the
connections according to the diagrams of
pages 44, 45 or 46.
▪ Lack of sensing.
▪ Faulty electronic circuit.
▪ Sensing voltage incompatible with
regulator.
▪ Check if alternator phases are present in the
sensing.
▪ If the regulator is encapsulated, replace it.
(*) For battery diesel generator where the alternator neutral is grounded battery should always be used independently.
15 PREVENTIVE MAINTENANCE
Periodical inspections of
the equipment are required to ensure they are clean, dust and moisture free. It is essential that
all terminal and connections are kept free from corrosion.
16 WARRANTY
See Installation and Maintenance Manual for WEG Alternators.
WEG Group - Energy Business Unit
Jaraguá do Sul - SC - Brazil
Telefono: 55 (47) 3276-4000
energia@weg.net
www.weg.net
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