ACBU-A1 (ABB) | Active Crowdbar Surge Suppressor
ACBU-A1 is an active surge suppressor (Active Crowbar) designed by ABB specifically for medium to high voltage frequency conversion/converter systems. Its core function is to respond quickly and discharge DC side overvoltage, protecting the frequency converter, inverter, rectifier bridge, and capacitor from high-voltage impacts caused by lightning strikes, grid flicker, and load short circuits. It is commonly used in wind power converters, metallurgical transmission, and grid energy storage systems.

1、 Basic Information
Model: ACBU-A1
Type: Active Crowbar (Active Surge Suppression/Overvoltage Protection Module)
Manufacturer: ABB
Applicable systems: ACS800/ACS880 multi drive, wind power converter SVG/STATCOM、 Medium voltage frequency conversion (such as ACS2000)
Installation method: Cabinet wall mounted/rail mounted installation
Weight: Approximately 2.5-3 kg
Protection level: IP20 (for use inside industrial cabinets)
2、 Core functions
Active overvoltage clamp: Real time monitoring of the DC bus voltage, triggered in microseconds when it exceeds a threshold (such as 1250 VDC). Surge energy is directly discharged to the ground/braking resistor through high-power thyristors to avoid overvoltage breakdown of DC capacitors and power devices.
Extremely fast response speed: response time<20 µ s, much faster than traditional varistors/SPDs, can effectively suppress lightning surges, operating overvoltages, and load short-circuit spikes.
Self recovery+repeatable action: automatically shuts off after overvoltage disappears, can act multiple times without the need to replace components; Built in fault self diagnosis, capable of outputting dry contact alarm.
High energy discharge capacity: It can discharge tens of kJ level surge energy in a single operation, with a peak current of 10-20 kA, and is suitable for 500 kW-2 MW power electronic equipment.
3、 Electrical specifications (typical values)
DC working voltage: DC 600 V -1800 V (suitable for 690 V/1000 V/1500 V systems)
Trigger voltage threshold: default 1250 VDC (can be fine tuned through software/dialing)
Surge current capacity: 15 kA (8/20 µ s); 5 kA (10/350 µ s, lightning strike)
Release energy: maximum 50 kJ per operation
Control power supply: 24 VDC ± 10%, power consumption<15 W
Action lifespan: ≥ 1000 times (full energy action)
Environmental temperature: -20 ℃~+55 ℃ (industrial standard)
4、 Typical application scenarios
Wind power converter: DC bus overvoltage protection for doubly fed/direct drive wind turbines to resist grid drops/lightning strikes
Metallurgy/Steel Rolling: ACS800 multi drive DC side surge suppression to prevent damage to the frequency converter from rolling mill load impact
Grid Energy Storage/SVG: Energy Storage Converter (PCS), Static Var Generator High Voltage Side Protection
Medium voltage drive: ACS2000 medium voltage frequency converter DC bus overvoltage protection
Photovoltaic inverter: DC side lightning strike/overvoltage protection for large photovoltaic power plants
5、 Difference from ordinary SPD
Ordinary SPD (Pressure Sensitive/Gas Discharge Tube): Passive, slow response (µ s-ms level), limited energy, prone to aging and explosion, suitable for low-voltage auxiliary circuits.
ACBU-A1 (Active Crowbar): Active triggering, microsecond level ultra fast response, high energy release, repeatable action, with diagnosis, specially designed for medium and high voltage high-power power electronic main circuits.