BASLER APM2000 Paralleling Module - Load Sharing Accessory for Parallel Generator Sets | OEM Replacement

BASLER APM2000. This is a Paralleling Module (AVR accessory) from the BASLER range, supplied as a direct replacement for the same model number in the field. The figures that matter are printed in the table above and repeated here so the page can be read on its own: field current rating Not published for this model - ask us, field resistance window Not published for this model, accuracy Not applicable, working range -40 to +60 degC. Everything else on this page exists to explain how those four numbers decide whether the unit fits a particular alternator.

Excitation architecture. Not applicable, accessory module. 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. Load sharing between parallel sets is set up with an instrument, not by ear. A droop adjustment made by listening to the sets will be wrong at every load other than the one it was set at.

Sensing. Takes the AVR sensing and CT signals. 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. Terminal boxes are hot, dirty and vibrating. Anything mounted inside one should be judged on how it behaves in year eight, not on how it reads on the bench.

Power stage and field drive. Power input Supplied from the AVR control supply, output Control signal to the AVR. Field current rating Not published for this model - ask us, forcing capability Short-term forcing current available for load steps, field resistance window Not published for this model. 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. Not applicable steady-state accuracy, Not applicable, 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 measurement that settles most arguments is the field current at full load, taken with a clamp meter, compared against the rating on the board.

Frequency behaviour. Rated for 50 / 60 Hz, with Not published for this model - ask us for the nameplate data. 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. Counterfeit regulators are a real problem on the widely copied boards. Buy from a source that will state where the board was made.

Paralleling. Active and reactive load sharing between paralleled generator sets. 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. Terminal boxes are hot, dirty and vibrating. Anything mounted inside one should be judged on how it behaves in year eight, not on how it reads on the bench.

Protection built into the regulator. Reverse power, loss of excitation and dead-bus protection at system level. 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. 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.

What it fits. Basler DECS and AVC regulators in multi-set installations. 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 trim potentiometer is not a calibration device. If rated voltage is not reachable near the middle of its range, the sensing tap is wrong.

Field notes on this model. The APM is not an AVR. It is the paralleling module that sits between several AVRs and makes them share kW and kvar instead of fighting each other. If a site has two or more sets running in parallel and the kvar is swinging between machines, the fault is usually in the load-sharing wiring or the APM, not in the regulators.

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 APM2000 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.

Wiring practice that prevents most call-backs. Run the sensing leads as a twisted pair, separate from the field cables, and land them on the terminals the drawing names rather than on the ones that happen to be nearest. On a APM2000 the sensing input draws very little current, which is exactly why it is vulnerable: a loose terminal adds resistance that the regulator reads as a voltage error and corrects by pushing the field up, so the machine runs hot and high for no visible reason.

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.

Temperature drift of the field. Copper rises about 0.4 per cent in resistance per degC, so a field that measures 12 ohm cold will measure around 15 ohm at a 70 degC winding temperature. A regulator set up on a cold machine and never re-checked will therefore be running at a different operating point every time the season changes, and the symptom is a voltage that is correct in winter and low in summer.

Spares strategy. Keep one regulator of each family in stock rather than several of one. A failed AVR takes a set off line in seconds and the replacement lead time is measured in days, which is why the cost of the spare is trivial compared with the cost of the outage.

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.

What the customer is actually buying. When a regulator is quoted as a replacement, the buyer is not purchasing a circuit board. They are purchasing the certainty that the set will hold voltage on the next load step. On the APM2000 that certainty comes from the combination of Not published for this model - ask us for the nameplate data continuous field current and the Not applicable response, and it disappears the moment the field resistance drifts outside the window the board was set up for.

Power and sensing are not the same circuit. The power input on a APM2000 can come from a different winding from the sensing input, and on PMG machines it always does. Wire them as two separate circuits, fused separately, and label both. The single most expensive mistake on a PMG set is landing the sensing leads on the PMG supply, which gives the regulator a voltage reference that rises with speed and produces a set whose voltage tracks engine rpm.