BASLER AVC110-6 Analogue AVR - Analogue Automatic Voltage Regulator for BASLER Alternators | OEM Replacement

Short version. The AVC110-6 is a Analogue Automatic Voltage Regulator. It supplies the exciter field, senses the alternator output and corrects the difference several times a second. Its rating is 6 Adc continuous, its field resistance window 15 ohm, its accuracy +/-1.0 per cent, and it is intended for machines whose field winding sits inside that window. Read the rest of this page as the detail behind those three figures.

Excitation architecture. Self-excited. That single sentence decides most of the regulator's behaviour in a fault: whether the field survives a close-up short circuit, whether the machine builds up from residual voltage on its own, and how much the terminal voltage dips when a large motor starts on the same bus. A regulator rated for a minimum field resistance of a few ohms will not drive a high resistance field to full current, however good its specification looks on paper.

Sensing. Single-phase, 110-220 V class. The sensing circuit is the regulator's only view of the outside world, so its wiring matters as much as its specification. A voltage error introduced by a loose terminal or a long run of untwisted cable is indistinguishable, from the regulator's point of view, from a genuine voltage error on the alternator. Conformal coating is the difference between a board that survives a coastal site and one that corrodes quietly in eighteen months.

Power stage and field drive. Power input Single-phase, 50 / 60 Hz, output 110 Vdc class. Field current rating 6 Adc continuous, forcing capability Short-term forcing current available for load steps, field resistance window 15 ohm. These are not independent numbers: the output voltage ceiling and the field resistance together set the maximum current the board can actually deliver, and the continuous rating is only reachable at the low end of the resistance window. Any AVR that has been in service for more than ten years is running on borrowed time, and the failure always happens at the least convenient moment.

Accuracy and response. +/-1.0 per cent steady-state accuracy, About 20 ms, thermal drift Low thermal drift. In practice the accuracy figure is the least interesting of the three. What an operator notices is recovery after a load step, which is governed by response and by available forcing current, and what a maintenance engineer notices after two years is drift, which is governed by the reference circuit and the ambient temperature inside the terminal box. The most common cause of intermittent excitation loss is a crimp terminal that was never properly made. Wiggle the harness with the machine running before replacing anything.

Frequency behaviour. Rated for 50 / 60 Hz, with Volts-per-hertz roll-off. The frequency-sensitive function exists to protect the prime mover, not the alternator: as engine speed falls the regulator reduces excitation so the alternator stops demanding torque the engine cannot supply. Without it, an overloaded engine is dragged down until it stalls, and the alternator is blamed for a fault that belongs to the fuel or governor system. A regulator rated for a minimum field resistance of a few ohms will not drive a high resistance field to full current, however good its specification looks on paper.

Paralleling. Reactive droop via CT. On a single set this circuit does nothing. On two or more sets it is the only thing that stops the machines from exchanging reactive power in a slow oscillation, and it is the first place to look when a parallel installation shows a circulating current that nobody can explain. The trim potentiometer is not a calibration device. If rated voltage is not reachable near the middle of its range, the sensing tap is wrong.

Protection built into the regulator. Over-excitation shutdown. These functions protect the alternator and the regulator, not the installation. Downstream protection, loss of mains and reverse power all belong to the controller, and a site that relies on the AVR for them is a site that will eventually trip in a way nobody can explain. If the machine will not hold voltage at all, disconnect the field and measure the sensing voltage first. That one reading separates a sensing fault from a field fault.

What it fits. Mid-size alternators. Lifecycle status: In production. Both halves of that sentence matter at order time. A board that fits perfectly but has been discontinued is a different commercial decision from one that fits and is in current production, and the price difference rarely reflects the difference in risk. If the machine will not hold voltage at all, disconnect the field and measure the sensing voltage first. That one reading separates a sensing fault from a field fault.

Field notes on this model. The AVC110-6 is a 110 Vdc analogue regulator for alternators whose exciter field is wound for the 110 V class. It is the direct alternative to the AVC63 series where the field resistance is too high for a 63 Vdc supply to reach rated field current.

Reading the application backwards. Most regulator problems arrive described as engine trouble. A set that hunts on load, or whose voltage sags for two seconds after a contactor closes, is usually reporting a field current limit rather than a fuel problem. On a AVC110-6 the first thing to check is whether the 6 Adc continuous figure is being reached on a cold morning, because field resistance rises with temperature in the opposite direction to copper and a board that is marginal at 20 degC can be comfortable at 50 degC or the other way round depending on the winding.

Documentation that survives the job. Photograph the terminal block before disconnecting anything, and write the sensing tap and the field resistance on the inside of the terminal box lid. Ten years later that note is the only thing that will let the next engineer choose a replacement without a full survey.

When the trim runs out of range. If full rotation of the voltage trim still will not bring the machine to rated voltage, the sensing tap is wrong. Moving one tap changes the reference by a factor of about two, so the correct tap is the one that puts rated voltage near the middle of the trim range rather than at either end.

Series resistance is not a fix. Adding a resistor in series with the field to bring it inside a regulator window costs forcing current exactly when the machine needs it most. If the field resistance is outside the window, change the board, not the circuit.

Voltage drifts with ambient temperature. If the voltage is correct cold and low hot, the thermal drift of the regulator and the temperature coefficient of the field are adding up in the same direction. The AVC110-6 is specified at +/-1.0 per cent; a drift of a couple of per cent over a fifty degree swing is normal for an analogue board and is not a fault.

Warranty and what it covers. A one year warranty on a regulator is meaningful only if it covers a field-side failure and not just a dead-on-arrival check. Ask whether a board that fails after six months in service is replaced without argument, because that is the failure mode that actually happens.

Parallel operation is a different animal. A single set on an island load only has to hold voltage. Two sets in parallel also have to agree about reactive load, and that agreement is made or broken by the droop circuit, not by the voltage accuracy. If a site is going to parallel, the regulator choice has to be made with the droop method in mind from the beginning, because retrofitting load sharing onto a board that was never specified for it costs more than buying the right one.

Earthing and shielding. The regulator reference is the machine frame. Bond the AVR mounting plate to the frame with a dedicated conductor rather than relying on the mounting screws, and earth the sensing cable shield at one end only. When a set shows a voltage that wanders slowly with no load change, the cause is usually a circulating current in the shield rather than a failing board.