PSTX105-600-70 softstarter: motor current, voltage range and start sequence

The PSTX105-600-70 is an ABB softstarter for three-phase motor starting and stopping. ABB identifies a maximum operational current of 105 A, a 208–600 V AC operating span and a 100–250 V AC control supply. Its built-in bypass and selectable voltage or torque ramp support panel integration, but the correct current rating depends on motor duty and the actual start profile.

Key technical data

The values above are intended to identify the listed version and support an initial technical review. Confirm applicable standards, rating conditions, installed accessories and the current ABB documentation for the serial number or revision before design approval, replacement or commissioning.

Application and engineering focus

Compare motor full-load current and starting conditions with the PSTX rating for the intended connection method and duty. Heavy starts, high inertia, frequent starts or elevated ambient temperature can require derating or a different size. Review current limit, kick-start, ramp time, motor heating and pump-control needs against the driven equipment. The softstarter reduces electrical and mechanical stress during transition; it is not a variable-speed drive for continuous speed regulation.

Configuration, compatibility and related references

Coordinate upstream short-circuit protection, bypass path, overload protection and motor thermal protection. Confirm whether the installation is in-line or inside-delta and follow the applicable ABB tables for the exact current and fault level. The control-supply voltage is separate from the main motor voltage. Verify programmable inputs, relay outputs, analog output and communication requirements against the actual project and the unit’s option configuration.

The related designations below are comparison references, not automatic substitutes. Confirm the complete type code, order number, interface, ratings and revision against the approved application before selecting an alternative.

• PSTX85-600-70
• PSTX142-600-70
• PSTX170-600-70

Installation and commissioning checks

The IP00 device requires enclosure protection, adequate cooling and access to terminals. Check conductor sizing, grounding, spacing, heat dissipation and bypass wiring before energizing. Commission with the motor uncoupled or under a controlled load where practical. Validate phase sequence, ramp behavior, current limit, bypass transition, stop mode and protection trip signals. Record the final parameter set and coordinate alarm/trip settings with the motor and process teams.

During commissioning, verify the nameplate, configuration, wiring and diagnostics before enabling normal operation. Test the relevant signal path or protection response end to end under controlled conditions. Record settings and as-left measurements, and investigate abnormal values at the sensor, load, wiring or system configuration before replacing components.

Ordering, replacement and application information

For a quotation or replacement review, provide the complete designation 1SFA898109R7000 PSTX105-600-70, ABB order code where available, serial or hardware revision, quantity, installation environment, connected equipment, interface requirements and target delivery date. Include a clear rating-label photograph and relevant wiring, loop or panel drawing when possible.

Ask the supplier to confirm the exact configuration, accessories, revision and any approved successor in writing. Do not select solely from a family name or product photograph. For safety, grid-protection, medium-voltage or regulated applications, obtain review by the responsible qualified engineer and follow local codes and the manufacturer’s instructions.