Protection Fuse - WEG AVR-A-OPT-06 400Hz Manual De Instalación, Operación Y Mantenimiento

The principle of operation is based on the comparison of the RMS sensing voltage with the reference voltage, adjusted by
the sum of the values of Vad trimpot and the external trimpot. The error is processed by the sensing loop and its value
determines the firing angle of the thyristor, which can vary from 0 to 180°, thus controlling the output voltage of the
alternator. With zero degree firing, the result is zero volts on the output side of the rectifier, and 180 degrees results in
maximum output of the half wave rectifier.
Generation starts through the alternator residual voltage. After the voltage has reached approximately 10% of the nominal
value, the regulator controls the voltage of the alternator, taking it through an initial ramp up of approximately 1 second
until reaching nominal voltage. From this point on, the sensing loop will maintain the output voltage of the alternator
constant within the adjusted value.
Figure 4.3 shows the control diagram of the AVR-A-OPT-06 voltage regulator. The control it's based in ST1A, shown by
IEEE, and applied to systems where the rectifier is fed from the output of the alternator (Type ST – Static Excitation
Systems), directly or through auxiliary coils or through a transformer.

5 PROTECTION FUSE

The fuse is used to limit the input current supply in order to extinguish the current in case of failure, avoiding major
problems. The AVR-A-OPT-06 regulator possesses a rectifier that controls the field voltage of the alternator. For the
maximum field voltage, the supplied current at input "3" is half of the field current, and the maximum current of the fuse
should be a little more than half of the current supplied by the regulator. Listed below are some of the fuse characteristics:
Recommended manufacturer: LittelFuse
Characteristics: Fast action fuse.
Dimensions: 5x20 mm.
Current/Voltage: 5A/250V.
Time for opening (to blow):
% of maximum current
Figure 4.3: Control diagram AVR-A-OPT-06
Table 5.1: Fuse opening time
Fuse opening time
110%
135%
200%
Opening time
4 hours (minimum)
Max. 1 hour
Max. 1 second
Automatic Voltage Regulator – AVR-A-OPT-06 400Hz l 15
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