ABB 5366268-B | Replacement Firing Board for PSS Series Soft Starter Maintenance

Brand ABB

Model ABB 5366268-B

Product Overview

The ABB 5366268-B is the internal control and thyristor-trigger printed circuit board that serves as the computational and firing core of ABB’s PSS (Parameter Setting Softstarter) family of compact three-phase soft starters. As a genuine ABB component, the 5366268-B houses the microcontroller responsible for executing the soft-start and soft-stop ramp algorithms, managing current-limit control, and driving the gate pulses to the power thyristors that regulate motor voltage during starting and stopping sequences. The ABB 5366268-B is specifically designed for PSS soft starters covering frame sizes from approximately PSS18 through PSS570, depending on production revision and serial prefix.

In the operational architecture of a PSS soft starter, the ABB 5366268-B functions as the central intelligence that coordinates all protection and control functions. It monitors motor current via internal current transformers on the power board, evaluates supply voltage for under-voltage and phase-loss conditions, and generates the timing signals that control the firing angle of the inverse-parallel SCR pairs. When a PSS soft starter fails to initiate the start ramp, displays a persistent fault indication without external cause, or exhibits erratic SCR firing behavior, the ABB 5366268-B is frequently the suspect component due to aged electrolytic capacitors, damaged gate-drive optocouplers from short-circuit events, or corrupted EEPROM settings.

Positioned as a critical spare part for legacy PSS installations, the ABB 5366268-B enables cost-effective repair of soft starters that might otherwise require complete replacement. The PSS series has been succeeded by newer PST(B) and PSTX ranges, making the 5366268-B an essential MRO component for facilities maintaining existing PSS soft starters installed from the late 1990s through the 2000s. Correct matching of the board revision to the soft starter’s power rating and series code is essential for proper operation.

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Description

Technical Specifications

Parameter Name	Parameter Value
Product Model	5366268-B
Manufacturer	ABB
Product Type	Soft Starter Internal Control / Thyristor Trigger Board (PCB Assembly)
Compatible Soft Starters	PSS18, PSS25, PSS30, PSS37, PSS44, PSS45, PSS57, PSS72, PSS85, PSS105, PSS142, PSS250, PSS370, PSS570 (verify by serial/rating plate)
Microcontroller Function	Soft-start/soft-stop ramp generation, current-limit control, bypass contactor control logic
Protection Features Managed	Overload, phase loss, undervoltage, overvoltage, SCR short detection
Gate Drive Outputs	6 isolated SCR gate-drive signals (to 3 inverse-parallel thyristor pairs)
Current Sensing Inputs	Via internal CTs on main power board (ratio-matched to PSS frame size)
Status Outputs	RUN, READY, FAULT LEDs; optional relay outputs via power board
Board Supply Voltage	Derived from PSS internal auxiliary supply (typically 20–30 V DC)
Operating Temperature	-10 °C to +60 °C (ambient inside starter enclosure)
Storage Temperature	-40 °C to +85 °C
Mounting	Standoff/pillar mount inside PSS housing; connects via multi-pin header
Dimensions (Approx.)	120 × 90 mm (varies by revision)
Weight	Approximately 80–120 g

Main Features and Advantages

Dedicated Soft-Start Control Architecture: The ABB 5366268-B is purpose-built to execute ABB’s proven soft-start algorithms, providing smooth motor acceleration without the electrical and mechanical stresses associated with direct-on-line or star-delta starting. The board manages adjustable ramp times from 1 to 30 seconds, initial voltage settings from 30% to 70% of full voltage, and optional current-limit functionality that maintains starting current at a pre-set level for heavy-duty applications . When paired with an external current transformer, the ABB 5366268-B enables precise current regulation that protects both the motor and the supply network from transient overloads during demanding start conditions.

Integrated Protection and Diagnostic Capabilities: The ABB 5366268-B continuously monitors system conditions to detect and respond to fault events before they escalate into equipment damage. Its firmware evaluates supply voltage for under-voltage and over-voltage conditions, detects phase loss or imbalance, and identifies SCR short-circuit events through coordination with the power board. Status indication is provided through front-panel LEDs for power supply, completed start ramp, general fault, and external fault conditions, giving maintenance personnel immediate visibility into soft starter health . The ABB 5366268-B also supports bypass contactor control logic, automatically transitioning the motor to direct online operation after the start ramp completes to minimize energy losses and heat generation.

Reliable Gate Drive for Power Thyristors: The ABB 5366268-B generates six isolated gate-drive signals that control the firing angle of three pairs of inverse-parallel silicon-controlled rectifiers. These opto-isolated drivers ensure accurate and repeatable SCR triggering across the full range of the soft starter’s current ratings, from 18 A in-line applications up to 515 A in inside-delta configurations . The gate-drive circuitry is calibrated at the factory for the specific SCR characteristics and CT ratio of the PSS frame size it serves, ensuring that the ABB 5366268-B delivers consistent performance when correctly matched to its host soft starter.

Cost-Effective Maintenance Solution: For facilities operating legacy PSS soft starters, the ABB 5366268-B offers a practical alternative to replacing the entire soft starter assembly when control board failure occurs. Replacing the ABB 5366268-B along with any visibly damaged power-stage components typically restores full functionality at a fraction of the cost of a new soft starter, making it an attractive option for MRO budgets and planned maintenance programs. The board’s compact form factor and standardized mounting simplify field replacement, minimizing downtime during repair operations.