BASLER XR2002F Analogue AVR - Analogue Automatic Voltage Regulator for BASLER Alternators | OEM Replacement

Short version. The XR2002F 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 4-8 Adc depending on model, 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 or PMG. 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. The cheapest diagnostic tool in excitation work is a DC ammeter in the field circuit. It turns a vague symptom into a number within seconds.

Sensing. Single-phase sensing, jumper-selectable range. 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. Vibration kills more regulators than heat does. If a board has failed twice in the same machine, look at the mounting before looking at the supplier.

Power stage and field drive. Power input Single-phase, 50 / 60 Hz, output 63 Vdc / 125 Vdc class. Field current rating 4-8 Adc depending on model, 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. On a machine that has been standing for months, check residual voltage before condemning anything: a winding that has lost its remanence will not build up on any regulator.

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. Where a board has been superseded, the replacement usually fits the same footprint but not the same terminal numbering. Read the drawing, do not read the old wiring.

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. Where a spare is being held, hold the drawing with it. A board without its wiring diagram costs a shift of production time to install.

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. Conformal coating is the difference between a board that survives a coastal site and one that corrodes quietly in eighteen months.

Protection built into the regulator. Over-excitation shutdown, loss of sensing. 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. A voltage that is correct at no load and low at full load is almost never an accuracy problem. It is a current limit, a resistance problem or a cable problem.

What it fits. Stamford-compatible and Basler-compatible 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. The measurement that settles most arguments is the field current at full load, taken with a clamp meter, compared against the rating on the board.

Field notes on this model. The XR2000 series is Basler's replacement regulator for older brushless alternators whose original AVR is obsolete. The suffix letters matter: the plain unit is the base analogue regulator, the F version adds a frequency-sensitive volts-per-hertz roll-off for engine-driven sets, and the V version is configured for a different sensing window. Ordering the wrong suffix is the most common mistake on this family.

Standby versus prime power. A standby set runs a few hundred hours a year and its regulator spends most of its life cold; a prime power set runs continuously and its regulator spends its life at operating temperature. The XR2002F is rated for -40 to +60 degC, which is fine in both cases provided the terminal box has any ventilation at all. What changes between the two duties is the capacitor ageing inside the board, not the semiconductor, so a prime power machine should have the regulator inspected on a schedule rather than on failure.

The terminal box is a hostile place. Engine vibration, radiant heat from the exhaust and conductive dust all arrive at the same panel. Mount the XR2002F on the resilient side of the box if there is a choice, keep it off the hottest wall, and make sure the lid actually closes over the wiring rather than pinching it. A regulator that is mechanically stressed will eventually crack a solder joint, and the resulting fault looks exactly like a failed semiconductor.

What to record. Write down the sensing tap used, the field resistance cold, the field current at no load and at full load, and the voltage trim position. Those four numbers turn the next service visit from an investigation into a comparison.

Why resistance matters more than current rating. A regulator delivers a voltage, and the field decides how much current that voltage produces. A board rated at 4-8 Adc depending on model into a low resistance field will deliver far less into a high resistance one, because the output voltage is the limit. This is why an AVR that is electrically perfect on paper can fail to excite a particular alternator, and why the resistance figure belongs in the quotation rather than in the manual.

Symptom first, board second. A set that will not build up voltage has one of four causes: no residual magnetism, a broken sensing circuit, a failed regulator, or a field circuit open. Test them in that order, because the first two are free to check and the third is not. Flashing the field with a battery through a resistor will separate a residual problem from a regulator problem in under a minute.

Part numbers are not interchangeable across suffixes. On this family the suffix carries the field current class, the sensing arrangement or the frequency band, and two boards that look identical in a photograph can be a hundred per cent different in rating. Quote the full model number including the suffix, and where the suffix is unclear send a photograph of the original board with the terminal markings visible.

Standby versus prime power. A standby set runs a few hundred hours a year and its regulator spends most of its life cold; a prime power set runs continuously and its regulator spends its life at operating temperature. The XR2002F is rated for -40 to +60 degC, which is fine in both cases provided the terminal box has any ventilation at all. What changes between the two duties is the capacitor ageing inside the board, not the semiconductor, so a prime power machine should have the regulator inspected on a schedule rather than on failure.

The terminal box is a hostile place. Engine vibration, radiant heat from the exhaust and conductive dust all arrive at the same panel. Mount the XR2002F on the resilient side of the box if there is a choice, keep it off the hottest wall, and make sure the lid actually closes over the wiring rather than pinching it. A regulator that is mechanically stressed will eventually crack a solder joint, and the resulting fault looks exactly like a failed semiconductor.