Problems, Causes And Corrective Actions; Preventive Maintenance; Warranty - WEG GRT7-TH4E Manual De Instalación, Operación Y Mantenimiento

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14 PROBLEMS, CAUSES AND CORRECTIVE ACTIONS

Problems
There is circulation of reactive power
between alternators when operating in
parallel.
Generated voltage decreases when load is
applied, and it does not return.
Alternator voltage does not increase.
Generated voltage oscillates at no load.
Voltage oscillates at a specific load point.
Voltage surges.
(*) 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.
18 l Automatic Voltage Regulator – GRT7-TH4E / GRT7-TH4PE
Table 14.1
Causes
▪
Phases sequence (R-S-T) incorrectly
connected;
▪
CT connections are inverted;
▪
Droop adjustment excessively low.
▪
Dropping speed of the driving machine;
▪
Under frequency protection engaged.
▪
Residual voltage excessively low.
▪
Inverted F+ and F- terminals.
▪
Terminals F+ and F- are inverted.
▪
Dynamic not well adjusted.
▪
Alternator excitation voltage excessively
low.
▪
Third harmonic of the auxiliary coil is
high.
▪
Lack of sensing.
▪
Faulty electronic circuit.
▪
Sensing voltage incompatible with
regulator.
WEG Group - Energy Business Unit
Jaraguá do Sul - SC - Brazil
Telefono: 55 (47) 3276-4000
energia@weg.net
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Corrective Actions
▪
Connect phase sequence correctly.
▪
Correctly polarize the CT in the phase shown
below:
S1
Alternator
P1
▪
Increase droop adjustment, rotating trimpot
P2 clockwise (CW).
▪
Correct speed regulation.
▪
Adjust Under frequency protection by rotating
trimpot P5 clockwise (CW).
▪
With the regulator switched- on, use external
battery (12Vdc) to force excitation (*).
▪
Invert F+ and F-.
▪
Invert F (+) and F (-).
▪
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.
▪
Eliminate auxiliary coil and proceed with the
connections according to the diagrams of
pages 44, 45 or 46.
▪
Check if alternator phases are present in the
sensing.
▪
If the regulator is encapsulated, replace it.
S2
Load
P2