WEG AVR-A-OPT-03 Installation, Operation And Maintenance Manual page 15

9 TRIMPOTS ADJUSTMENT
Vad = Rotating it clockwise, the voltage increases;
Stb = Rotating it clockwise, the system becomes faster;
U/F = Rotating it clockwise, the U/F range increases;
Drp = Rotating it clockwise, the reactive compensation range increases.
NOTE
1. A potentiometer may be connected for fine voltage adjustment (5 k / 3 W) at terminals identified
by this symbol
2. The U/F and Stb trimpots were preseted and sealed, but if adjustments are required, They can be
performed according to the procedures described in this manual.
10 LED INDICATION
OK: Regulator OK (For AVR-A-OPT-03/B and AVR-A-OPT-03/C)
Exc: Over current (Only on AVR-A-OPT-03/C)
Hz: Low Rotation – under frequency protection (Only on AVR-A-OPT-03/C)
11 OPERATION
11.1 VOLTAGE REGULATOR
It compares the real voltage value coming from the alternatoroutput with the theoretical value adjusted through the voltage
adjustment trimpot, plus the external voltage adjustment (if available). The error is processed by the sensing stage, which
value determinate the thyristor trigger angle that can vary from 0 to 180°, controlling this way the alternatorvoltage output.
11.2 POWER CIRCUIT CONNECTION
The Voltage that comes from the auxiliary coil is connected to the E3/4 and 3 terminals (or N in version AVR-A-OPT-03/C).
This rectified voltage is applied to the alternatorexciter field.
11.3 VOLTAGE BUILD UP
The residual voltage should start the regulator to build up the output alternatorvoltage. If a low output voltage the regulator
control circuitry supplies the entire power input to the field voltage.
When the output voltage reaches an acceptable value the PI control starts acting.
If the residual voltage is not enough, a field flashing with external batteries is needed. So, the output voltage will build up
enough to supply a voltage to the regulator that will start to control the output voltage.
11.4 PARALLEL OPERATION WITH TWO OR MORE GENERATORS
The reagent compensation system adopted is named phase diagram composition (see Figure 11.1). In this kind of system,
the alternatoroutput voltage signal is taken and the composition with the alternatorcurrent signal it's made.
The result of this interaction introduces a sensing error in the real voltage signal, causing an increase or decrease in the
alternatorvoltage, keeping the reactive power between the generators (sharing) inside of acceptable values. The
adjustment of this compensation is made by droop adjustment trimpot.
.
Analog Voltage Regulator AVR-A-OPT-03
www.weg.net
| 15