Basler AVC125-10A1 Automatic Voltage Regulator: Complete Technical Guide
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What is the Basler AVC125-10A1 voltage regulator?
The AVC125-10A1 is a Basler automatic voltage regulator (AVR) in its Caterpillar-supplied form — every white box label reads AVC125-10A1, CATERPILLAR, with the unit serial below — and this record covers three of them, new in their boxes with the instruction manual (the Basler manual for the VR6 / K65-12B / K125-10B regulator family) and a bag of mounting bolts. The rating label on the back states the full specification: AVC125-10-A1, serial 220930118, POWER INPUT shunt excited 180–264 Vac 50/60 Hz 3 phase, SENSING INPUT 90–240 Vac 50/60 Hz 1 QR 3 phase, CT INPUT 1 or 5 Aac 50/60 Hz, ACC INPUT ±3 Vdc, OUTPUT 125 Vdc @ 10 Adc, CE. The board face shows the big finned heatsinks, three large 105 °C electrolytics, a bank of five DIP switches labelled DRP / FAC CAL / VLT ADJ / UF KNEE / STB for the standard adjustments, and the two terminal rows (CH GND, 2, 3, 5, 5a, 6, 6a, 8, 9 and 20, 22, 24, 26, 28, 30, F1, F2) with the factory jumpers in place. New in original packaging; they passed through the Koeed warehouse on 28 July 2025, and the eight photos and video below show them as received.
Part details
| Field | Value |
|---|---|
| Manufacturer | Basler Electric — Caterpillar-supplied version (box labels read CATERPILLAR) |
| Model | AVC125-10A1 (label: AVC125-10-A1); serials 20241011001001, 20250723007010, 20241011001003 |
| Function | Automatic voltage regulator for brushless generator excitation, shunt-excited |
| Power input | 180–264 Vac, 50/60 Hz, 3 phase (shunt excited) |
| Sensing input | 90–240 Vac, 50/60 Hz, 1 QR, 3 phase |
| CT input | 1 or 5 Aac, 50/60 Hz |
| Analog input | ACC INPUT ±3 Vdc |
| Output | 125 Vdc @ 10 Adc (exciter field) |
| Adjustments | Five DIP switches: DRP, FAC CAL, VLT ADJ, UF KNEE, STB |
| Terminals | CH GND, 2, 3, 5, 5a, 6, 6a, 8, 9 (top); 20, 22, 24, 26, 28, 30, F1, F2 (bottom); factory jumpers 5-5a and 6-6a fitted |
| Extras | Instruction manual (VR6 / K65-12B / K125-10B family), bag of four bolts with washers, anti-static bag |
| Quantity | 3 regulators |
| Condition | New in original packaging (per intake record) |
| Intake recorded | 28 July 2025 |
Fitting notes
This is the regulator class fitted to Caterpillar generator sets — the 125 V / 10 A output drives the exciter field directly, the shunt input takes power from the generator output, and the CT input gives the underfrequency knee and droop circuits their load signal. The five DIP switches are where commissioning happens: frequency-related protections (UF KNEE), droop (DRP), and stability (STB) all set from the bank, so photograph the old unit's switch positions before swapping. Keep the factory 5-5a and 6-6a jumpers unless your wiring diagram says otherwise, land F1/F2 to the exciter field observing polarity, and torque the four mounting bolts from the supplied bag. The three units are serially distinct but identically configured — a matched set for one genset rebuild or a spares shelf.
Photos and video
All images below are original warehouse photos of the exact regulators covered by this record, taken before dispatch. Click any photo to view it full size.
Sourcing help
KOEED supplies Basler voltage regulators and generator excitation spares, in active and EOL stock. Send the part number for a quote.
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