ABB PST Series Soft Starters — PST142-690-70

Technical Dossier

Product Details And Specifications

ABB PST Series: Comprehensive Module Range and Technical Overview

The ABB PST Series represents one of ABB's most widely deployed soft starter platforms across global heavy industry. Installed in chemical processing plants, oil refineries, nuclear auxiliary systems, pulp and paper mills, and offshore platforms, the PST range provides controlled motor acceleration and deceleration for three-phase induction motors rated from 3 A to 1250 A. The series operates across a supply voltage range of 208–690 V AC (50/60 Hz), making it compatible with both North American and European industrial infrastructure. Its integrated bypass contactor, built-in motor protection functions (phase loss, overload, thermistor input), and DIN rail or panel-mount form factor have made it a standard specification in MCC (Motor Control Center) builds worldwide. The PST Series is produced at ABB's Västerås facility in Sweden and carries CE, UL, and cUL certifications, meeting IEC 60947-4-2 and NEMA standards.

The Evolution of PST Series Architecture

ABB introduced the PST platform in the early 1990s as a successor to discrete thyristor-based motor starters. The first-generation PST units (PST3 through PST85) established the core architecture: six anti-parallel SCR (silicon-controlled rectifier) pairs in a three-phase bridge configuration, controlled by a microprocessor-based firing angle ramp. These units used analog potentiometer-based parameter setting and offered limited protection functions.

The mid-generation PST expansion (PST105 through PST370) introduced digital parameter storage, improved thermal modeling for overload protection, and extended the operating voltage ceiling to 690 V to address European industrial requirements. Integrated bypass contactors became standard in this generation, reducing heat dissipation during full-voltage run mode and extending SCR service life.

The high-current PST range (PST470 through PST1250) addressed large pump, compressor, and fan applications. These units feature forced-air cooling, copper bus bar connections, and modular SCR assemblies designed for field replacement without full unit removal. Communication options (Profibus DP, DeviceNet, Modbus RTU) were introduced as optional plug-in modules in this generation.

The PST Series has entered its mature/end-of-life phase. ABB's current soft starter platform is the PSTX Series, which supersedes PST with an expanded protection suite, built-in fieldbus (EtherNet/IP, Profibus, Modbus), and a graphical HMI. Facilities operating PST units should plan for lifecycle extension support rather than direct replacement, as PSTX is not a drop-in mechanical or electrical substitute in all enclosure configurations.

PST Series Full Catalog & Functionalities (SKU List)

The following SKUs represent the verified ABB PST Series product range, organized by current rating and function. Each unit is a three-phase soft starter with integrated bypass unless otherwise noted.

PST3-600-70: 3 A / 600 V soft starter, DIN rail mount, basic ramp control, smallest PST form factor.
PST6-600-70: 6 A / 600 V soft starter, panel or DIN rail mount, integrated overload relay function.
PST9-600-70: 9 A / 600 V soft starter, suitable for small conveyor and pump applications up to 4 kW.
PST16-600-70: 16 A / 600 V soft starter, motor protection class 10, thermistor input standard.
PST30-600-70: 30 A / 600 V soft starter, phase sequence and phase loss detection included.
PST45-600-70: 45 A / 600 V soft starter, adjustable current limit and kick-start function.
PST60-600-70: 60 A / 600 V soft starter, integrated bypass contactor, reduced panel heat load.
PST85-600-70: 85 A / 600 V soft starter, dual ramp profiles, suitable for high-inertia loads.
PST105-690-70: 105 A / 690 V soft starter, extended voltage range, Profibus DP option available.
PST142-690-70: 142 A / 690 V soft starter, integrated bypass, motor protection class 10/20 selectable, DeviceNet option.
PST175-690-70: 175 A / 690 V soft starter, forced-air cooling, suitable for compressor and pump duty.
PST210-690-70: 210 A / 690 V soft starter, copper bus bar terminals, panel mount with DIN rail adapter.
PST250-690-70: 250 A / 690 V soft starter, modular SCR assembly, field-replaceable power stack.
PST300-690-70: 300 A / 690 V soft starter, extended overload protection, suitable for high-cycle applications.
PST370-690-70: 370 A / 690 V soft starter, dual cooling fans, Modbus RTU communication option.
PST470-690-70: 470 A / 690 V soft starter, heavy-duty frame, suitable for large centrifugal pump stations.
PST570-690-70: 570 A / 690 V soft starter, forced-air cooling with thermal cutout, MCC panel integration.
PST720-690-70: 720 A / 690 V soft starter, high-current bus bar design, suitable for 400 kW+ motors.
PST840-690-70: 840 A / 690 V soft starter, modular SCR pairs, field service kit available.
PST1050-690-70: 1050 A / 690 V soft starter, largest standard PST frame, refinery and compressor station duty.

Sourcing Hard-to-Find & Obsolete PST Series Parts

The ABB PST Series is no longer in active production. ABB has transitioned its soft starter portfolio to the PSTX platform. As a result, PST units — particularly mid-range models such as the PST105-690-70, PST142-690-70, PST175-690-70, and PST210-690-70 — are increasingly sourced through the secondary market and specialist distributors rather than through ABB's standard distribution channel.

DriveKNMS maintains a dedicated inventory of PST Series units and sub-components, including SCR modules, bypass contactors, control boards, and communication plug-in modules. For facilities operating PST units in critical service (cooling water pumps, boiler feed pumps, compressor trains), DriveKNMS provides lifecycle extension support: verified used units with full functional test documentation, refurbished units with 12-month warranty, and sub-component repair for control PCBs where OEM replacement is unavailable.

Procurement teams managing long-term maintenance contracts for PST-equipped MCCs are advised to establish a consignment stock arrangement to avoid unplanned downtime. DriveKNMS can assess your installed base and recommend minimum stock levels based on unit age, duty cycle, and criticality classification.

Quality Control for the PST Series Range

The PST Series presents specific test challenges due to its integrated bypass contactor architecture and SCR-based power stage. DriveKNMS applies the following test protocol to all PST units processed through its facility:

Incoming inspection: Visual inspection of SCR heat sink surfaces, bypass contactor contact condition, and control terminal block integrity. Units with evidence of thermal damage to the SCR mounting surface are quarantined for power stack assessment before further testing.

Control board functional test: The control PCB is powered independently at 24 V DC (control supply) and verified for correct parameter retention, display function (where applicable), and communication port response (RS-485 / Profibus DP).

SCR firing test: Each SCR pair is tested for correct gate trigger response, forward voltage drop (VT), and reverse blocking voltage. Out-of-tolerance SCRs are replaced with matched-pair devices from verified stock.

Bypass contactor test: Contactor coil resistance, contact resistance (milliohm measurement), and mechanical operation are verified. Contacts showing pitting or elevated resistance are replaced.

Full-load simulation: Where facility capacity permits, units rated up to PST210-690-70 are tested under resistive load at rated current for a minimum of 30 minutes. Higher-current units (PST250 and above) are tested at 50% rated current with thermal imaging to verify heat distribution across the SCR assembly.

Final documentation: Each unit ships with a test report recording all measured parameters, technician ID, test date, and firmware version (where applicable).