Application Scenarios

In a mining hoist application using an ABB ACS 607​ drive, the hoist suddenly faults with a “DC LINK OVERVOLTAGE” alarm during a rapid descent. This indicates that the regenerative energy from the descending load cannot be dissipated. The root cause is a failed ABB SNAT617CHC​ chopper control board, which is responsible for activating the braking IGBT/Thyristor. Replacing this board restores the drive’s ability to safely burn off excess energy, allowing the hoist to maintain controlled deceleration and prevent damage to the DC bus capacitors.

 

Parameter

Main Parameters	Value/Description
Product Model​	ABB SNAT617CHC​ (Ordering Code: 61037136D)
Manufacturer​	ABB
Product Category​	Chopper Control Board / Brake Unit Control Module
Compatible System​	ABB ACS600 Series (e.g., ACS 607, ACS 617, ACS 677)
Primary Function​	Controls the braking chopper thyristor/IGBT to dissipate regenerative energy
Control Method​	Monitors DC bus voltage and generates precise firing pulses
Power Supply​	+24 V DC (typically sourced from the drive’s internal PSU)
Control Current​	Designed for drives with braking currents of 100–400 A
Communication​	Interfaces with the drive’s main control unit (RDCU)
Status​	Discontinued​ (Obsolete), available as spare part only

 

 

Technical Principles and Innovative Values

The ABB SNAT617CHC​ is a specialized protection and control module that solves a critical problem in variable frequency drives (VFDs): energy dissipation.

• Innovation Point 1: Dynamic Voltage Regulation:​ The board continuously monitors the DC bus voltage. When the motor regenerates (e.g., during fast stops or downhill loads), the voltage rises. The SNAT617CHC’s logic detects this rise and calculates the exact firing angle needed for the chopper thyristor to “dump” the excess energy into the external braking resistor, clamping the voltage to a safe level (e.g., 760-800V). This prevents catastrophic overvoltage trips and potential capacitor explosions.
• Innovation Point 2: Integrated Protection Logic:​ Unlike generic boards, the SNAT617CHC integrates directly with the ACS600’s fault management system. It provides hardware-level protection​ against chopper overcurrent and short-circuits. If the braking resistor circuit fails, the board can block pulses and signal the main controller to shut down safely, protecting the power semiconductors from damage.
• Innovation Point 3: Seamless System Integration:​ The board is designed as a plug-in module within the ACS600’s rack system. It works in tandem with the RDCU​ (main control board) and RMIO​ (I/O board), receiving commands and providing status feedback. This modular design allows for quick replacement without rewiring the entire drive, minimizing downtime in industrial plants.

 

Application Cases and Industry Value

A steel plant’s plate mill, driven by an ACS 617​ drive, experienced random overvoltage faults during the roll gap adjustment, causing production stoppages. The issue was traced to an intermittent SNAT617CHC​ board that was failing to activate the braking resistor during rapid roll reversals. By replacing the faulty board with a certified refurbished unit and verifying the resistor’s ohmic value, the mill eliminated the faults. This intervention restored the drive’s ability to handle dynamic load changes, ensuring continuous operation and protecting the expensive DC link components from stress, thereby extending the drive’s service life.