20-750-S PowerFlex 750 Safe Torque Off Option Module | Allen-Bradley

The Original New Allen-Bradley 20-750-S Safe Torque Off (STO) Option Module is a safety-rated component designed for PowerFlex 750 series drives (753 and 755). It provides a certified method to safely disable the drive's output by removing power from the IGBT gate firing circuits, preventing the output devices from switching and producing torque in the motor. This safety function ensures personnel and machine protection without the need to remove main power from the drive, minimizing downtime during maintenance or emergency situations.

The module achieves this through dual‑channel safety monitoring and advanced control mechanisms, providing a high level of protection to both personnel and machinery. In normal operation, 24V DC is applied to the safety power and safety enable inputs. If either is de‑energized, the gate driver IC output and IGBT firing are disabled, and the drive enters a safe state.

Core Engineering Highlights:
SIL 3 (IEC 61508) | PL e (ISO 13849-1) | Category 3 (EN 954-1) | Safe Torque Off (STO) | 24V DC logic voltage | 90 mA current draw | Safety reaction time ≤10 ms (Frames 1‑10) | Dual‑channel monitoring | Hardwired safety interface | Compatible with PowerFlex 753/755

Key Features:

• Original New Allen-Bradley 20-750-S module

• Certified Safe Torque Off (STO) functionality for PowerFlex 750 series drives

• Safety integrity: SIL 3 (IEC 61508, IEC 61800‑5‑2), PL e (ISO 13849‑1), Category 3

• Safety reaction time ≤10 ms maximum for drive Frames 1‑10

• Disables IGBT gate firing circuits to prevent motor torque production

• Hardwired safety interface for reliable integration

• 24V DC logic and signal voltage

• 90 mA current draw

• Digital logic I/O compatibility

• Status indicator LEDs for operational monitoring

• Transient and overcurrent protection on I/O signals

• Dual‑channel safety monitoring

• Coast‑to‑stop action (configurable for controlled stop with other safety devices)

• Mounts directly into a designated module slot inside the drive

• Compact design minimizes space requirements

• EMC/EMI compliant for demanding industrial environments

Applications:

• Industrial machinery requiring safe maintenance access

• Robotics and automated assembly lines

• Material handling systems

• Packaging equipment

• Conveyor systems and industrial fan/pump applications

• Applications needing functional safety without power cycling the drive

• Safety-critical operations requiring SIL 3 / PL e rated protection

• Emergency stop and fault condition safe shutdown

Technical Specifications:

System Compatibility:

• Rockwell Automation PowerFlex 753 drives

• PowerFlex 755 drives

• PowerFlex 750 series drive architecture

• 24V DC logic and signal systems

• Integrated Architecture platform

Installation Notes:

• The module mounts directly into a designated slot inside the PowerFlex 750 drive

• For Integrated Motion applications, the module must be installed in Port 6

• Safety reaction time from input signal trigger to initiation of configured Stop Type is 10 ms maximum for drive Frames 1‑10

• Test the safety function for proper operation after initial installation

• Retest the safety function at intervals determined by safety analysis

• In normal operation, apply 24V DC to both the safety power and safety enable inputs

Related Products:

• 20-750-S1 – Safe Torque Off option module variant with additional features

• 20-750-S2 – Safety interface adapter module supporting STO functions

• 20-750-APS – Auxiliary power supply for PowerFlex 750 series

• 20-750-2262C-2R – I/O module for PowerFlex 750 series

• 20-750-1132C-2R – Digital/analog I/O module

• 20-750-2263C-1R2T – I/O interface module with transistor and relay outputs

• 25B-D030N114 – PowerFlex 525 15kW AC Drive (alternative drive family)

• PowerFlex 753 – General-purpose AC drive up to 400 HP / 270 kW

• PowerFlex 755 – High-performance AC drive

PLC ERA is an independent industrial automation distributor supplying 100% genuine Original New products through established global supply channels. Allen-Bradley, PowerFlex, and Rockwell Automation are trademarks of Rockwell Automation.