Speed sensors

Speed sensors

In many industrial applications drives need to be monitored for rotational speed or standstill. In the automotive, food, steel and mining industries, speed sensors are used to safely detect standstill, overspeed and underspeed of drives or belt break on conveyors. On mobile machines such as fork-lift trucks, speed sensors serve as speed pick-ups.
Speed sensors integrate rotational speed detection and monitoring in one unit. The sensor head operates using inductive or magnetic sensing principles. The sensor detects metal actuating surfaces on a rotating machine part. The integrated evaluation converts this information into rotational speed.

What Is an Industrial Speed Sensor?

An industrial speed sensor is a compact device designed to monitor the movement of rotating or moving machine parts in real-time. It translates mechanical motion into electrical signals, which can then be interpreted by control systems for automation, diagnostics, or safety purposes.

Why Speed Sensors Matter in Industrial Automation?

Speed sensors are essential for maintaining process stability, enabling predictive maintenance, and optimising machine performance. They’re particularly useful in scenarios where consistent speed control or immediate detection of speed variation is critical.

How Do Industrial Speed Sensors Work?

Beyond basic speed detection, many modern sensors feature integrated signal conditioning, allowing them to output standardised signals (e.g. frequency, pulse, or analogue) directly to control systems. Some versions also include adjustable switching thresholds, allowing for direct overspeed or underspeed monitoring without the need for a separate controller.

Sensors typically rely on non-contact technology, detecting ferromagnetic or encoded targets as they pass through the sensor’s field, triggering a pulse. The interval between pulses is then converted into speed information.

Types of Industrial Speed Sensors

Frequency output sensors

• Emit a pulse signal each time a target (e.g. a gear tooth or magnet) is detected.

• Commonly used with PLCs and digital counters to monitor speed or display RPM.

Analogue output sensors

• Provide a continuous voltage or current output that varies in proportion to the speed.

• Suitable for applications requiring smooth control, such as variable-speed drives or process regulation.

Speed monitors with threshold settings

• Integrate sensing and switching in one unit, allowing the user to set upper and/or lower speed limits.

• Often used for direct control of alarms or shutdown mechanisms in case of overspeed or underspeed.

IO-Link enabled speed sensors

• Support digital communication for parameter setting, monitoring, and diagnostics.

• Ideal for smart factory environments and predictive maintenance systems where integration with Industry 4.0 is required.

Advantages and Disadvantages of Speed Sensors

Non-contact sensing

• Advantage: No physical wear and tear, resulting in longer sensor lifespan.

• Consideration: Requires a clear, unobstructed path between sensor and target.

Integrated evaluation electronics

• Advantage: Eliminates the need for external amplifiers or processing units.

• Consideration: May increase unit cost slightly compared to simpler sensors.

High switching accuracy

• Advantage: Can detect even slow or irregular motion with precision.

• Consideration: Sensor and target must be properly aligned for consistent performance.

IO-Link support

• Advantage: Enables advanced functions like remote configuration and live diagnostics.

• Consideration: Requires IO-Link compatible hardware and system architecture.