ABB UNS4908A 3ADT218437R0001 UNITROL 6000 Series Digital Excitation Controller

Product Description

UNS4908A (Part No.: 3ADT218437R0001) is a digital excitation controller (AVR, Automatic Voltage Regulator) of ABB UNITROL 6000 series, serving as the core master unit for synchronous generator excitation systems. This module collects generator terminal voltage and stator current signals. It calculates thyristor firing angles via built-in control algorithms and dynamically adjusts excitation output to stabilize generator terminal voltage and control reactive power and power factor. It integrates comprehensive fault diagnosis and protection logic with over-excitation, under-excitation, overcurrent and overtemperature protection, and supports redundant channel switching. Featuring strong anti-interference performance, it acts as critical spare part for excitation cabinets of medium and large generator sets.

Specifications

• Model: UNS4908A
• ABB Part Number: 3ADT218437R0001
• Type: Digital Excitation Controller / AVR Automatic Voltage Regulator
• Compatible Series: ABB UNITROL 6000 / UNITROL 6080 Excitation System
• 3-phase Voltage Sensing: up to 500V AC
• 3-phase Current Sensing: 3~50A AC
• Analog Input: 4~20mA / 0~10V DC configurable
• Digital Input: 8 isolated channels, 24V DC
• Auxiliary Power Supply: 18~32V DC (nominal 24V DC)
• Dimension: 483 × 311 × 111 mm
• Net Weight: 7.2 kg
• Operating Temperature: -20℃ ~ +60℃
• Storage Temperature: -40℃ ~ +85℃
• Protection Class: IP20 (installed inside cabinet)
• Functions: Generator voltage regulation, reactive power control, excitation firing control, fault diagnosis, over-excitation / under-excitation / overcurrent / overtemperature protection, redundant switching
• Certifications: CE, compliant with power industry excitation control standards

Applications

1. Master control unit for UNITROL 6000 excitation system of synchronous generators in thermal power plants and hydropower plants.
2. Voltage and reactive power stabilization control for generators in combined cycle gas power plants and self-owned power stations.
3. Excitation system retrofit, spare parts replacement and system expansion for generator sets.
4. Generator excitation control for self-owned power plants in metallurgy and chemical industries.
5. Grid-connected synchronous units to improve grid connection stability and realize unit protection interlock.

Series Models

UNS4908A V5004, UNS4908A V5006