Application Scenarios:

In a refinery’s safety instrumented system (SIS), two independent 24V DC power supplies are connected to an ABB SS832​ voting unit mounted on a DIN rail inside the controller cabinet. The SS832 continuously monitors both inputs. If one power supply fails due to a fuse blow or AC loss, the SS832 instantly (within milliseconds) isolates the faulty source and continues powering the AC 800M controller and S800 I/O modules from the healthy supply. Its front-panel LEDs and dry-contact “OK” signals alert the operator to the fault, allowing for maintenance without shutting down the critical safety system.

 

Parameter:

Parameter Category	Specification Details
Product Model​	ABB SS832​
Material Number​	3BSC610068R1​
Product Type​	Power Voting Unit / Redundant Power Control Module
Input Channels​	2 independent 24V DC inputs (18-30V DC range)
Output​	1 x 24V DC, 10A continuous​ (20A max in parallel operation)
Switching Time​	<10 ms​ (bumpless transfer during failure)
Status Indication​	Front-panel Green LEDs (Power OK), Fault relay contacts
Monitoring Output​	2 x Voltage-free “OK” contacts (for remote alarm)
Mounting​	35mm DIN Rail​ (TH35-7.5)
Dimensions (WxHxD)​	32 mm x 125 mm x 117 mm
Weight​	Approx. 0.45 kg
Operating Temperature​	0°C to +55°C (industrial standard)
Protection Features​	Overcurrent limit, Overvoltage (OVP), Short-circuit, Reverse polarity
Compatible PSUs​	ABB SD832, SD833, and other SD83x series

 

 

Technical Principles and Innovative Values:

• Innovation Point 1: Intelligent “Voting” Logic for Fault Tolerance:​ Unlike simple diode-OR circuits, the SS832​ incorporates active monitoring and voting logic. It continuously compares the health of both input sources based on voltage thresholds. If one source deviates outside the acceptable range (e.g., undervoltage), the module automatically and seamlessly disconnects it from the output bus, preventing a single point of failure from collapsing the entire control system.
• Innovation Point 2: Integrated Diagnostics and Remote Signaling:​ The module provides both local (LED) and remote diagnostic capabilities. Each channel has a dedicated “OK” relay contact​ that closes when the input is healthy. This signal can be wired directly to a PLC or DCS digital input, enabling the control system to generate an early alarm for a failing power supply before​ redundancy is lost, facilitating proactive maintenance.
• Innovation Point 3: High-Current Capacity in a Compact Form Factor:​ Despite its slim 32mm width, the SS832​ is rated for a robust 10A continuous output. This high power density allows it to support the full load of a densely populated controller rack without requiring oversized components. Two units can also be configured in parallel to deliver up to 20A, providing scalability for expanding systems.

 

Application Cases and Industry Value:

Case Study: Power Plant DCS Power System RetrofitA combined-cycle power plant’s legacy DCS was experiencing unexplained controller resets. Investigation revealed that the existing non-redundant power supplies were susceptible to voltage sags. The plant engineers retrofitted the system with a 1+1 redundant configuration​ using two ABB SD832 power supplies and one SS832​ voting unit. The SS832‘s fast switching (<10ms) ensured that the controllers did not experience a brownout during a sag event. The remote “OK” contacts were wired to the DCS, allowing the operators to immediately identify which power supply had failed. This upgrade eliminated the random resets and provided a cost-effective, high-availability power solution without replacing the entire control cabinet.