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The R250 AVR is an analog transistor automatic voltage regulator designed for brushless SHUNT-excitation generators from 20kW to 100kW, maintaining output voltage within ±0.5% of setpoint through a closed-loop excitation circuit that responds directly to alternator output changes without processing delays — giving the fast dynamic response needed in standby and industrial prime power applications where loads step on and off unpredictably. A built-in Load Acceptance Module (LAM) with selectable 0%, 13%, and 25% levels dynamically relaxes the undervoltage trip threshold during heavy load acceptance, allowing the engine and governor to recover without nuisance shutdowns, while an on-board 1000Ω voltage trim potentiometer enables ±5% field output adjustment during commissioning. Compliant with IEC, VDE, NEMA, BS, CSA, and UL508 international standards, the R250 AVR is a direct OEM-fit and replacement regulator card for Leroy-Somer LSA 42.2, 43.2, 44.2, 46.2, and 47.2 series alternators across 50Hz and 60Hz configurations, making it the preferred stock item for generator service companies, distributors, and OEM manufacturers maintaining or assembling LSA-platform generator sets worldwide.
The R250 AVR is a trusted automatic voltage regulator card built for brushless generators operating with SHUNT excitation systems, covering generator output ranges from 20kW to 100kW. This R250 AVR card uses analog transistor-based circuitry to continuously regulate excitation current in response to alternator output voltage, maintaining output regulation within ±0.5%. The R250 AVR operates across a supply range of 85V to 139V, ensuring compatibility with a wide range of alternator winding configurations. Generator technicians globally trust the R250 AVR for its proven analog design and low maintenance requirements across demanding field installations. The R250 AVR complies with IEC, VDE, NEMA, BS, CSA, and UL508 international electrical standards.
The R250 AVR functions on the principle of closed-loop excitation control, continuously comparing the alternator's actual output voltage to the setpoint and adjusting the transistor drive to maintain stable regulation. Unlike more complex digital regulators, the R250 AVR analog design keeps the circuit simple, delivering robust performance well-suited for generator sets where reliable, low-maintenance voltage control is a priority over long operating periods. This R250 AVR is built specifically for SHUNT excitation alternators, where the field winding draws its excitation supply directly from the alternator output through the regulator circuit, requiring no separate external excitation source.
The R250 AVR includes a precision voltage setting potentiometer rated 1000Ω/0.5W with a setting range of ±5%, allowing field technicians to fine-tune output voltage during commissioning. A standout feature of the R250 AVR is its Load Acceptance Module (LAM) capability, which dynamically adjusts the undervoltage protection threshold during sudden load impacts. When a heavy load steps onto the generator, the R250 AVR LAM circuit temporarily relaxes the undervoltage trip threshold, giving the engine and governor time to recover without nuisance tripping. This R250 AVR behavior makes it especially well-suited for standby power applications where step load changes can be large and rapid. The R250 AVR is compatible with Leroy-Somer LSA 42.2, 43.2, 44.2, 46.2, and 47.2 series alternators.
| Voltage Regulation | Around ±0.5% |
| Supply Range | 85V to 139V |
| Voltage Setting Potentiometer | 1000Ω / 0.5W, setting range ±5% |
| Operating Frequency | 50Hz or 60Hz |
| LAM Levels | 0% (without LAM), 13%, 25% |
| Generator Range | 20kW to 100kW brushless generators |
| Alternator Compatibility | LSA 42.2, 43.2, 44.2, 46.2, 47.2 |
| Standards Compliance | IEC, VDE, NEMA, BS, CSA, UL508 CE Low Voltage |
The R250 AVR delivers reliable excitation control through its analog closed-loop design, which responds directly to output voltage changes without the processing delays sometimes found in digital AVR architectures. This makes the R250 AVR capable of fast dynamic response to load transients, a characteristic that generator set operators value in applications with frequent or unpredictable load changes, such as manufacturing facilities and data center backup systems.
The R250 AVR LAM feature sets it apart from basic voltage regulators by actively managing the relationship between voltage stability and load acceptance performance during transient conditions. Generator OEM engineers specify the R250 AVR for its compliance with multiple international standards including IEC, VDE, and UL508, which simplifies regulatory documentation for generator sets sold across multiple markets. The R250 AVR broad alternator compatibility across the LSA 42.2-47.2 series reduces spare parts inventory requirements for service organizations maintaining diverse fleets. Field experience across a wide range of generator installations confirms the R250 AVR as a dependable choice for brushless alternator voltage control.
The R250 AVR is well-suited to a broad range of brushless alternator and generator set applications across industries and power levels:
Generator service companies and procurement teams specifying the R250 AVR gain a reliable, internationally-certified voltage regulator backed by a well-established global distributor network. The R250 AVR well-recognized compatibility with Leroy-Somer LSA alternators makes it a standard replacement part that generator technicians can source quickly, reducing equipment downtime when AVR failure occurs. Distributors stocking the R250 AVR benefit from steady replacement demand driven by the large installed base of LSA-series alternators in field use worldwide.
The R250 AVR multi-standard compliance (IEC, VDE, NEMA, UL508) supports export and certification documentation requirements for generator manufacturers supplying multiple global markets, reducing overhead in the regulatory approval process. Procurement teams choose the R250 AVR for its established market track record and predictable supply availability. Service organizations value the R250 AVR for its straightforward installation and commissioning process, which minimizes site setup time and keeps maintenance procedures simple. The R250 AVR consistent performance history across diverse field environments makes it a sound long-term investment for generator fleet operators maintaining mixed LSA alternator fleets.
Q1: What generator size range is the R250 AVR designed for?
A1: The R250 AVR is designed for brushless generators in the 20kW to 100kW output range.
Q2: What voltage regulation accuracy does the R250 AVR provide?
A2: The R250 AVR maintains generator output voltage within approximately ±0.5% of the target setpoint.
Q3: What alternator models is the R250 AVR compatible with?
A3: The R250 AVR is compatible with Leroy-Somer LSA 42.2, 43.2, 44.2, 46.2, and 47.2 series alternators.
Q4: What is the LAM function on the R250 AVR?
A4: The R250 AVR LAM (Load Acceptance Module) dynamically adjusts the undervoltage protection threshold during large step load changes, allowing the generator to recover without nuisance undervoltage tripping.
Q5: What supply voltage range does the R250 AVR operate on?
A5: The R250 AVR accepts supply voltages in the range of 85V to 139V, covering a wide range of alternator configurations.
Q6: Does the R250 AVR support both 50Hz and 60Hz operation?
A6: Yes, the R250 AVR supports both 50Hz and 60Hz generator operating frequencies, with separate LAM threshold settings configured for each.
The R250 AVR is an analog transistor automatic voltage regulator designed for brushless SHUNT-excitation generators from 20kW to 100kW, maintaining output voltage within ±0.5% of setpoint through a closed-loop excitation circuit that responds directly to alternator output changes without processing delays — giving the fast dynamic response needed in standby and industrial prime power applications where loads step on and off unpredictably. A built-in Load Acceptance Module (LAM) with selectable 0%, 13%, and 25% levels dynamically relaxes the undervoltage trip threshold during heavy load acceptance, allowing the engine and governor to recover without nuisance shutdowns, while an on-board 1000Ω voltage trim potentiometer enables ±5% field output adjustment during commissioning. Compliant with IEC, VDE, NEMA, BS, CSA, and UL508 international standards, the R250 AVR is a direct OEM-fit and replacement regulator card for Leroy-Somer LSA 42.2, 43.2, 44.2, 46.2, and 47.2 series alternators across 50Hz and 60Hz configurations, making it the preferred stock item for generator service companies, distributors, and OEM manufacturers maintaining or assembling LSA-platform generator sets worldwide.
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