PSTB1050-600-70 1050 A 208-600 V AC Soft Starter

The ABB PSTB1050-600-70 is a Switch for industrial control and automation applications.

ABB PSTB1050-600-70 is a soft starter rated 1050 A for in-line connection and 1810 A for inside-delta connection. Its main circuit accepts 208 ... 600 V AC, and the control supply range is 100 ... 250 V AC at 50/60 Hz.

What are the key electrical specifications of the PSTB1050-600-70?

The table below lists verified parameters for this model. All values are quoted from the manufacturer's data.

• Rated operational voltage (main circuit): 208 ... 600 V AC
• Rated operational current (in-line): 1050 A
• Rated operational current (inside delta): 1810 A
• Rated control supply voltage (Us): 100 ... 250 V AC
• Rated control circuit voltage (Uc): DC Operation 24 V
• Rated frequency: 50/60 Hz
• Rated operational power (in-line, 400 V): 560 kW
• Rated operational power (in-line, 500 V): 730 kW
• Current limit function: 1.5 ... 7xIe
• Starting capacity: 3xIe for 15s
• Ambient air temperature (operation): 0 ... +50 °C

How does built-in electronic overload protection simplify panel design?

Integrated electronic overload protection eliminates the need for a separate overload relay in many installations. The protection circuit monitors motor current continuously, and a dedicated overload signal relay provides a dry contact for external annunciation. Consequently, panel space and wiring are reduced while protection remains coordinated with the soft starter's current limit function.

The current limit function adjusts from 1.5 to 7 times the rated operational current, giving engineers precise control over starting torque. Ramp times are adjustable from 0 to 120 seconds, and initial voltage can be set between 30 and 70 percent. These settings allow the starter to match the driven load's torque profile.

Which applications benefit from inside-delta connection?

Inside-delta connection raises the rated operational current to 1810 A and the rated operational power to 1000 kW at 400 V or 1250 kW at 500 V. This configuration suits large motors where panel space is limited, because the soft starter carries phase current rather than line current. The built-in switch for inside-delta connection simplifies changeover during commissioning.

How should This unit be integrated into a control system?

The soft starter includes a FieldBusPlug as standard communication interface. Integration into a fieldbus network may require an external gateway or connection module; confirm cable and gateway compatibility with AutoDCSTech before ordering. Analog outputs are available as 0…10 volts, 0…20 mA, or 4…20 mA for remote monitoring.

Status indication is provided by three LEDs: green for ready to start/standby, yellow for protection, and red for fault. Four signal relays—run, by-pass, fault, and overload—offer flexible interfacing with PLCs or control panels.

What are the physical installation requirements?

The unit measures 436 mm wide, 515 mm high, and 381 mm deep, with a net weight of 60 kg. Main terminals accept bars with a 12.5 mm hole diameter and 40x6 mm width and thickness. Tightening torque is 45 N·m for the main circuit and 0.5 N·m for control and supply circuits. The main terminals are rated IP00 according to IEC 60529, so the soft starter must be mounted inside an enclosure.

Operating ambient temperature ranges from 0 to +50 °C, and storage temperature from -25 to +70 °C. The service factor is 100 percent, and the starter supports 10 starts per hour at 3.5 times rated current with 7-second starts and 50 percent on-time.