Product Overview

The ABB 1SF536268D1008 is the core motherboard and primary control unit for the ABB PSTX series of intelligent soft starters. As the “brain” of the soft starter system, this high-performance PCB board is responsible for executing all critical control, protection, and communication functions essential for smooth motor starting and stopping . The ABB 1SF536268D1008 integrates a powerful microprocessor, high-precision current and voltage sampling circuits, SCR (silicon-controlled rectifier) gate drive logic, and comprehensive fault diagnosis capabilities into a single compact, multilayer PCB design . It serves as the central processing hub that translates advanced control algorithms into precise firing signals for the six SCRs, enabling three-phase controlled soft start and stop through voltage or torque ramps .

The 1SF536268D1008 is a field-replaceable unit designed for straightforward maintenance, allowing technicians to restore a failed PSTX soft starter to full functionality by simply replacing the motherboard without the need to replace the entire unit . ABB has engineered this board with a conformal coating (protective lacquer) that shields the delicate electronic components from conductive dust, moisture, and corrosive atmospheres commonly found in industrial environments, significantly enhancing its reliability in harsh conditions . Its compatibility spans the entire PSTX product range from 30A to 1250A (and up to 2160A in inside-delta connection), making the ABB 1SF536268D1008 a versatile and essential spare part for maintaining critical motor control infrastructure across numerous industries .

 

Technical Specifications

Parameter Name	Value
Product Model	1SF536268D1008
Manufacturer	ABB
Product Type	Soft Starter Motherboard / Main Control Board
Series	PSTX Series
Primary Function	SCR gate drive, motor protection, communication processing
Rated Control Supply Voltage	100-250V AC, 50/60 Hz (wide-range)
Main Circuit Voltage Compatibility	208-690V AC
Current Range Support	30A to 1250A (up to 2160A inside-delta)
Communication Interfaces	Built-in Modbus RTU (RS485); optional Anybus for Profibus, Profinet, Ethernet/IP, DeviceNet
Digital Inputs	3 programmable inputs
Signal Relays	3 programmable relay outputs (Run, Top of Ramp, Event/Fault)
Analog Output	1 programmable output (0-10V, 0-20mA, 4-20mA)
Conformal Coating	Yes (standard, for PCB protection)
Operating Temperature	-25°C to +60°C
Storage Temperature	-40°C to +70°C
Degree of Protection	IP20 (control circuit terminals)
Weight	Approx. 0.5-1.5 kg (depending on configuration)

 

Main Features and Advantages

Intelligent Motor Control and Comprehensive Protection: The ABB 1SF536268D1008 executes advanced control algorithms that deliver smooth, controlled motor acceleration and deceleration. It supports multiple start and stop modes, including voltage ramp, torque control (ideal for pumps to reduce water hammer), current limit, kick start, and soft stop . The motherboard provides complete motor protection by continuously monitoring key parameters and responding to over 30 different fault conditions, such as electronic overload (EOL), locked rotor, undercurrent, over/under voltage, current imbalance, phase loss, earth fault, and PTC/PT-100 thermal sensor inputs . This comprehensive protection ensures that motors are safeguarded against both electrical and mechanical stresses, extending their operational life.

Flexible and Robust Communication: The 1SF536268D1008 is designed for seamless integration into modern automation networks. It features a built-in Modbus RTU interface via RS485 terminals, allowing direct connectivity to PLCs, HMIs, and SCADA systems . Additionally, the board supports the Anybus module option, enabling communication via major industrial protocols such as Profibus, Profinet, Ethernet/IP, DeviceNet, EtherCAT, and BACnet . This flexibility makes the ABB 1SF536268D1008 adaptable to various control system architectures, whether in a greenfield installation or a legacy system upgrade.

Built-in Bypass and Energy Savings: A key advantage of the PSTX series, controlled by the ABB 1SF536268D1008, is the integration of a built-in bypass contactor . Once the motor reaches full speed, the motherboard automatically closes the bypass, eliminating the continuous power dissipation that occurs in traditional soft starters. This significantly reduces heat generation within the cabinet, lowers energy costs, and extends the life of the power semiconductors by keeping them cool when not actively switching . The board also features an energy optimization function that reduces voltage during light-load conditions to minimize energy consumption and motor heating .