Your Technical Guide to the Allen-Bradley M100 Electronic Motor Starter
18/08/2025
In today’s fast-paced industrial world, motor control is about far more than simply starting and stopping motors — it’s about boosting productivity, streamlining engineering, and keeping operations safe and reliable. The all-new Allen-Bradley M100 Electronic Motor Starter from Rockwell Automation is designed to meet these modern demands, redefining what fixed-speed motor control can achieve.
Built for a wide range of industrial tasks, the M100 delivers reliable, precise, and safe motor control, keeping operations running smoothly and efficiently. Whether you’re managing water pumping, airflow, or material handling, it provides the performance and protection you need.
Common applications include:
- Conveyors: Smooth, safe control for material handling systems
- Pumps: Reliable control & protection for fluid transfer
- Fans: Efficient switching for ventilation and cooling systems
- Compressors: Robust control for high-demand air compression tasks
Transform your Motor Control Panel
The M100 brings together contactor switching and overload protection in one sleek, compact unit, covering AC-3 motor loads from 0.75A to 23A.
Choose from a range of versatile models:
- Direct-On-Line (DOL) Non-Reversing
- Direct-On-Line (DOL) Reversing
- DOL Non-Reversing with integrated Safe Torque OFFF (STO)
- DOL Reversing with integrated Safe Torque OFF (STO)
All models run on 24V DC control, making them easy to integrate into today’s modern control systems.
Panel Space Optimisation
Space is at a premium on every shop floor. With a housing size that’s significantly smaller than traditional motor starters – and integrated power, control and safety wiring – the M100 starters free up valuable space for additional components to be used in the control panel. With its compact profile, the M100 starter requires only 22.5 mm of panel width for 9 A models and just 45 mm for 23 A models.
Just how much more space savings do the M100’s provide over traditional motor starters?
Traditional Motor Starter v M100 A standard 9A (AC-3) contactor & connected electronic overload takes up 45mm in width space, the M100 fits the same rating in just 22.5mm.
Traditional Motor Reversing Starter v M100 Motor reversing applications that require 90 mm of width space for interlocked forward and reverse contactors now fit into just 22.5 mm or 45 mm width with the M100—a game-changing reduction that delivers substantial control-panel space savings.
Simplified Wiring & Component Selection
The M100 starter is engineered to make panel wiring and commissioning faster and more reliable. Its removable terminal blocks let you complete all control, power, and safety wiring offline — whether you prefer tool-free push-in connectors or traditional screw-type terminations — and then simply snap each block back into place.
The M100 combines contactor and overload functions into one device, making selection and installation easier. Instead of choosing separate components, you simply use one M100 starter to achieve the same functions. Component simplification also helps to significantly reduce the installation and wiring time to commission the motor starter.
When motor reversing capability is required, just select the M100 reversing model — no extra forward/reverse contactors or interlocking kits required. And for applications demanding functional safety, the integrated Safe Torque Off (STO) meets SIL 3 and PLe standards and eliminates the requirement of using separate safety contactors.
Point-On-Wave (POW) Switching
The M100 motor starter incorporates Rockwell Automation’s proprietary Point-On-Wave (POW) switching technology, enabling precise activation of contacts at optimal points on the AC voltage and current waveforms. This allows for independent and highly accurate control of each phase, thereby helping to reduce electrical stress and improving overall system efficiency. Uniquely positioned in its category, the M100 is the only motor starter in this product space to leverage POW switching—setting a new benchmark for performance.
When the M100 receives the signal to start the motor, it intelligently waits for the motor power switching voltage waveform to reach the zero-crossing point—the moment when the AC voltage transitions between positive and negative cycles and is momentarily at 0 volts.
The M100 enhances contact longevity and motor performance by synchronising switching with the AC voltage zero-crossing point. This precise timing significantly reduces inrush current and mitigates electrical stress on the contacts. By closing at zero voltage, the risk of arcing—typically caused by switching under high potential—is greatly minimised. Arcing not only generates excessive heat but also accelerates contact wear. Through zero-voltage switching, the M100 ensures smoother engagement, reduced thermal impact, and extended contact life, making it a robust solution for reliable fixed speed motor control.
When the motor needs to stop, the M100 doesn’t just break the circuit arbitrarily, it monitors the current waveform. The M100 aims to open the contacts when the current is near zero, which is the point of least energy flow. Opening contacts near current zero reduces the chances for arcing from forming between contacts thereby also preventing damage and heat buildup. It also minimises electromagnetic interference and enables accurate fault detection like contact weld monitoring.
POW based switching using voltage and current waveforms Importance of POW Switching
The M100 motor starter incorporates Rockwell Automation’s proprietary Point-On-Wave (POW) switching technology, enabling precise activation of contacts at optimal points on the AC voltage and current waveforms. This allows for independent and highly accurate control of each phase, thereby helping to reduce electrical stress and improving overall system efficiency. Uniquely positioned in its category, the M100 is the only motor starter in this product space to leverage POW switching—setting a new benchmark for performance.
When the M100 receives the signal to start the motor, it intelligently waits for the motor power switching voltage waveform to reach the zero-crossing point—the moment when the AC voltage transitions between positive and negative cycles and is momentarily at 0 volts.
- Enhanced Diagnostics: Reduced arcing, mechanical and electrical contact stress means that the contacts last longer, thereby lowering maintenance costs and getting a longer service life from the M100
- Compact, Efficient Design: POW switching enables a thermally efficient design and layout, allowing for smaller form factors without compromising starter performance
- Enhanced Diagnostics: Enables features like contact weld detection capability
- Superior Thermal Performance: Unlike solid-state switching, POW relays dissipate less heat, improving reliability in dense panel configurations
Functional Safety Built-In
The M100 is built for use in high-demand safety applications, such as emergency stopping or safe torque-off (STO) functions in machinery. It meets SIL 3 under IEC 61508 and Performance Level e (PLe) under ISO 13849-1 — both representing the highest levels of safety integrity and reliability.
Safe Torque OFF (STO)
M100 motor starters are available in safety-rated models that incorporate the Safe Torque Off (STO) function. When STO is activated, the motor is electrically prevented from generating torque, ensuring that it cannot perform any unintended movement. This safety feature enables qualified personnel to carry out maintenance activities with reduced risk of mechanical hazards. Importantly, STO is implemented without cutting power to the control electronics. This not only enhances operational safety but also streamlines maintenance procedures, offering a practical and efficient solution for plant personnel.
Fast, Reliable Safety Response
The M100 motor starter is designed to respond to safety events in 100 milliseconds or less. This is the time when a safety input becomes invalid (de-energized) to when the starter transitions to a safe state — halting motor operation. Speed matters in industrial environments, milliseconds can make the difference between a near miss and a serious incident. A fast safety response:
- Minimises risk to personnel
- Can prevent equipment damage
- Ensures compliance with SIL 3 systems
Dual Safety Inputs (S12/S22)
The M100 features two safety inputs (S12 and S22) designed to monitor signals from external safety devices. These inputs support both traditional dry-contact and OSSD (Output Signal Switching Device) signals with pulse testing. While dry-contact inputs are commonly used in devices such as emergency stop buttons and basic interlock switches—supporting up to PLd / SIL2—OSSD signals, typically found in advanced safety devices like light curtains and laser scanners enable the M100 to achieve PLe / SIL3 safety ratings. The M100’s hard-wired 24V DC Type 1 inputs include pulse filtering and mismatch detection, ensuring reliable and standards-compliant safety control. Connected devices must also meet SIL3 requirements to maintain system integrity at that level.
Robust Safety Architecture
The M100 motor starter is designed for long-term reliability, with a proof test interval of 20 years and monthly safety demand validation to ensure ongoing performance. It's also optimised for high-demand operations where frequent safety actions are required, providing dependable protection in even the most intensive applications.
- Category 3 design tolerates single faults without compromising safety
- Hardware Fault Tolerance (HFT) of 1 (1oo2)
- Redundancy is built in. If one safety channel fails, the other ensures continued protection
- Low Probability of Dangerous Failure. The M100 motor starter features exceptionally low PFH (Probability of Dangerous Failure per Hour) values, supporting reliable performance in safety-critical applications and simplifying compliance with risk assessment standards
Motor Asset Protection
The integrated electronic overload in the M100 protects motor assets from damage under a range of conditions. Based on the proven Allen-Bradley E100 electronic overload relay, it allows users to seamlessly set the Full Load Amps (FLA) value for their application using the dial on the front face. Depending on the M100 model selected, the available ranges are 0.75A–9A or 4.6A–23A. The M100 electronic motor starter also features integrated overload protection with a Class 10 trip curve, allowing the motor to draw up to six times its set FLA for up to 10 seconds during start-up without tripping. If the elevated current continues beyond this interval, the overload protection activates, de-energising the motor to prevent thermal damage. The device can also accurately detect conditions such as phase loss, phase imbalance & contact weld:
Phase Loss
The M100 starter offers phase loss protection for three-phase motors, issuing a warning after 0.1 seconds and triggering a fault after 3 seconds. Faults are indicated by the Motor Status LED flashing a trip code as detailed in the installation manual.
Phase Imbalance
The M100 trips a 3-phase motor if current imbalance exceeds 50% and average current is over 30% of FLA for at least 10 seconds.
Contact Weld Detection
If any of the output contacts have welded together due to arcing, the M100 detects this and trips the motor instantly to prevent further damage or unsafe conditions.
Clear Diagnostics
The M100 is equipped with intuitive LED indicators that display real-time information about the starter’s status, motor condition, safety inputs, and fault states. These visual cues help operators quickly assess system health without needing external tools.
M100 Safety Motor Starter Front Plate Why it matters:
- Fast Fault Identification: LED fault codes correspond to specific issues, allowing for quick and accurate troubleshooting
- Reduced Downtime: Clear diagnostics mean faster recovery from faults, keeping operations running smoothly
- Simplified Maintenance: Technicians can easily interpret status indicators, streamlining service and support
Contact Us
For more information on the M100 Motor Starter range, get in touch with your local NHP Account Representative or email us:
Australia | 1300 NHP NHP | nhpservice@nhp.com.au
New Zealand | 0800 NHP NHP | servicenz@nhp-nz.com