Problems, Causes And Corrective Actions; Preventive Maintenance; Warranty - WEG GRT7-TH4 Manual De Instalación, Operación Y Mantenimiento

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14 PROBLEMS, CAUSES AND CORRECTIVE ACTIONS

Problems
- There is circulation of reactive power
between generators when operating in
parallel.
- Generated voltage decreases when load
is applied, and it doesn't return.
- Generator 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 generator 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 G Line Generator.
20 | Automatic Voltage Regulator - GRT7-TH4
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.
- Terminals F (+) and F (-) are inverted.
- Dynamic not well adjusted.
- Generator excitation voltage excessively
low.
- Third harmonic of the auxiliary coil is
high.
- Lack of sensing.
- Faulty electronic circuit.
- Sensing voltage incompatible with
regulator.
WEG Equipamentos Elétricos S.A.
International Division
Av. Prefeito Waldemar Grubba, 3000
89256-900 - Jaraguá do Sul - SC - Brazil
Phone: 55 (47) 3276-4002
Fax: 55 (47) 3276-4060
www.weg.net
Corrective Actions
- Connect phase sequence correctly.
- Correctly polarize the CT in the phase shown
below:
S
S
Generator
P
P
- 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 (12Vcc) to force excitation (*).
- Invert F (+) and F (-).
- Adjust trimpots P3 and P4;
- Insert 10/100W resistor in series with field.
- Eliminate auxiliary coil and proceed with the
connections according to the diagrams of page
13.
- Check if generator phases are present in the
sensing.
- If the regulator is encapsulated, replace it.
Load