The R450 is an Automatic Voltage Regulator (AVR) designed for alternators, providing voltage regulation and excitation control. It is a key component in electric power generation systems, ensuring stable and reliable power output.
Function Description
The R450 AVR is responsible for maintaining a constant output voltage from the alternator by controlling its excitation current. It can operate in various excitation systems, including AREP (Auxiliary Regulation Excitation Permanent Magnet), PMG (Permanent Magnet Generator), and SHUNT (separate excitation). The AVR continuously monitors the alternator's output voltage and adjusts the excitation to compensate for load changes, speed variations, and other factors that might affect voltage stability.
Key functions include:
- Voltage Regulation: The primary function is to regulate the alternator's output voltage within specified limits, typically ±0.5% to ±1% of the rated voltage.
- Excitation Control: It controls the current supplied to the alternator's exciter field, which in turn controls the main alternator field.
- Load Acceptance Module (LAM): This feature improves load acceptance by temporarily boosting the excitation during sudden load applications, preventing excessive voltage dips and engine speed drops.
- Under-frequency Protection (U/F): The AVR reduces the output voltage when the alternator speed drops below a preset threshold, protecting the alternator from damage due to prolonged operation at low speeds.
- Over-excitation Protection: It limits the maximum excitation current to prevent damage to the alternator's exciter and main field windings.
- Short-circuit Protection: In the event of a short-circuit, the AVR limits the excitation current to a safe level, allowing the circuit breakers to clear the fault without damaging the alternator.
- Parallel Operation: The R450 can be configured for parallel operation with other alternators, allowing for load sharing and increased power generation capacity. This is achieved through droop compensation, which ensures stable load distribution between paralleled units.
- Remote Voltage Adjustment: The output voltage can be adjusted remotely using an external potentiometer, providing flexibility in system control.
Important Technical Specifications
- Voltage Sensing: The R450 can sense voltage in single or three phases, with a measurement range typically from 95 V to 140 V, 170 V to 260 V, or 340 V to 528 V, depending on the configuration.
- Frequency Range: Operates at 50 Hz or 60 Hz. The AVR automatically adapts to the detected frequency.
- Maximum Power Supply: 150 V - 50/60 Hz.
- Rated Overload Current: 10 A for 10 seconds.
- Electronic Protection: The AVR is protected against short-circuits, loss of voltage reference, and over-excitation.
- Vibrations: Less than 10 Hz, 2 mm half-peak amplitude; 10 Hz to 100 Hz, 100mm/s, above 100 Hz, 8 g.
- Operating Temperature: -40°C to +65°C.
- Storage Temperature: -55°C to +85°C.
- Shocks: 9 g depending on the 3 axes.
- Voltage Regulation Accuracy: Typically ±0.5% to ±1% of the rated voltage in steady state.
- Response Time: The AVR has a fast response time to voltage changes, ensuring quick recovery from load transients.
- Auxiliary Windings (AREP): Powered by two auxiliary windings which are independent of the voltage sensing circuit. This provides a robust excitation source, especially during short-circuits.
- PMG Excitation: Utilizes a permanent magnet generator (PMG) to supply the AVR, offering a highly reliable and independent excitation source, particularly beneficial for motor starting and short-circuit performance.
- SHUNT Excitation: Powered by the main winding (100V to 140V - 50/60Hz) by using X1, X2 on the AVR.
Usage Features
The R450 AVR is designed for ease of installation and commissioning. It features several potentiometers and switches for adjusting its operating parameters:
- P1 (Voltage Potentiometer): Adjusts the alternator's output voltage.
- P2 (Stability Potentiometer): Controls the AVR's stability, preventing oscillations and ensuring smooth voltage regulation.
- P3 (Excitation Potentiometer): Adjusts the maximum excitation current, used for setting the ceiling excitation.
- P4 (Quadrature Droop Potentiometer): Used for parallel operation to ensure proper load sharing between alternators.
- Rotating Switches (LAM and U/F): These switches allow selection of different LAM (Load Acceptance Module) and U/F (Under-frequency) knee-point positions, optimizing the AVR's response to load changes and low-speed conditions.
- Rotating Switches (Excitation Type and Time Response): These switches configure the AVR for different excitation systems (AREP, PMG) and adjust the time response for excitation.
- LED Indicators: The AVR includes LEDs (VOLT, STAB, I EXC, LEDS) that provide visual feedback on its operating status, such as voltage stability, excitation current, and fault conditions.
- Fuses: Equipped with 10A fuses for protection against overcurrents.
- Terminal Block: Clearly labeled terminals for easy connection of voltage sensing, excitation output, and auxiliary power.
Maintenance Features
Maintenance of the R450 AVR primarily involves periodic checks and, if necessary, replacement of components.
- Visual Inspection: Regularly inspect the AVR for any signs of physical damage, loose connections, or overheating.
- Electrical Checks: Verify the voltage and current readings at various points to ensure the AVR is operating within specifications. This includes checking the connection voltage reference to the AVR, the continuity of rotating diodes, and the field windings.
- Potentiometer Adjustments: Periodically check and recalibrate the potentiometers (P1, P2, P3, P4) to ensure optimal performance. This is particularly important after any significant changes to the alternator or load conditions.
- Fault Diagnosis: The manual provides a comprehensive fault table that lists common faults, their actions, effects, and check/cause. This aids in quick troubleshooting and resolution of issues. For example, if there is no voltage at no load on start-up, the manual suggests checking connections, diodes, and field windings.
- Component Replacement: In case of a fault, specific components like diodes, field windings, or the AVR itself may need to be replaced. The manual provides guidance on identifying defective components.
- Technical Support: Leroy-Somer offers technical support services, including spare parts orders, technical support requests, and information on product codes.
- Disposal and Recycling: The manual provides instructions for the proper disposal and recycling of the AVR and its components, emphasizing environmental responsibility. This includes separating electronic materials, transformers, interference suppression modules, diode bridges, and plastic components.
The R450 AVR is a robust and reliable device, but proper installation, commissioning, and maintenance are crucial for its long-term performance and the overall stability of the power generation system.
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