Reed switches - Application in conjunction with magnetic actuator used for magnetic sensing devices
1Key Takeaways
1 Scope This part of IEC 62246 gives additional requirements for the evaluation of functional characteristics on reed switching components operated by magnetic actuator and gives guidance for their implementation in selected applications. This document specifies test and measure…
2Expert Interpretation
This article provides an in-depth analysis of the IEC 62246-4:2023 standard, covering the technical requirements, test methods, and implementation recommendations for the combined application of reed switches and magnetic actuators, offering an authoritative reference for the design of magnetic sensing devices.
Background and Technological Evolution of Standard Development
Reed switches, as a passive magnetic switching element, have long played an important role in position detection, liquid level sensing, and safety interlocking. With the increasing reliability requirements of industrial automation, the combined application of magnetic actuators and reed switches urgently needs unified standards. IEC 62246-4:2023, as Part 4 of this series of standards, specifically sets forth additional requirements for magnetic sensing devices (MSDs) composed of reed switches and magnetic actuators. Released in 2023, this standard replaces related clauses previously scattered across various product standards, marking a significant milestone in the standardization of magnetic sensing devices.
Comparison of Core Terminology and Framework
The standard clarifies six types of MSDs: split, locking, fork, plunger, float, and definitions related to magnetic interference.
Comparison of Core Terminology and Framework
The standard clarifies six types of MSDs: split, locking, fork, plunger, float, and definitions related to magnetic interference.
The following table compares the characteristics of various types:
| Type | Operating Principle | Characteristics | Typical Applications |
|---|---|---|---|
| Separate Type | External Magnet Proximity Trigger | Flexible Installation, Adjustable Distance | Door and Window Magnetic Switch |
| Lock-in Type | Built-in Bias Magnet Self-holding | Retains Status After Power Failure | Security Door Monitoring |
| Fork Type | Ferromagnetic Plate Inserted into U-shaped Slot | Anti-drying Disturbance-free, magnet-free liquid level detection | |
| Plunger type | Internal magnet moves with the plunger | Mechanical guidance, precise stroke | Limit switch |
| Float type | Magnet inside the float moves with the liquid level | Continuous liquid level measurement | Tank liquid level sensing |
Key Test Methods Explained
The standard specifies detailed test procedures, among which the **response speed test** and **operating frequency test** are key to ensuring dynamic performance. For example, the response speed test requires measuring the output signal time t1 as shown in Figure 1 to ensure reliable operation at typical speeds (e.g., 10000 mm/s). The operating frequency test uses a rotating disk to simulate pulse input to verify whether the sensor can operate normally within 500 Hz.
Key Test Methods Explained
The standard specifies detailed test procedures, among which the **response speed test** and **operating frequency test** are key to ensuring dynamic performance. For example, the response speed test requires measuring the output signal time t1 as shown in Figure 1 to ensure reliable operation at typical speeds (e.g., 10000 mm/s). The operating frequency test uses a rotating disk to simulate pulse input to verify whether the sensor can operate normally within 500 Hz. In addition, environmental adaptability testing covers cold, heat, humidity, and salt spray to ensure the stability of the sensor under harsh conditions. For example, the deviation of the operating distance under temperature changes must not exceed ±30% as shown in Table 18. Implementation Recommendations Based on standard requirements, manufacturers are advised to pay attention to the following points in their designs: Clearly indicate the rated operating distance (Sn), repeatability (R), and differential travel (H), and refer to the illustrations in Appendix C of the standard. Conduct a risk assessment of the MSD (see Appendix D), identify failure modes such as contact adhesion and glass breakage, and take appropriate protective measures. Regarding electromagnetic compatibility, since purely mechanical reed switches do not generate electromagnetic interference, no additional EMC testing is required, but attention should be paid to magnetic field interference from surrounding solenoids. For applications requiring explosion-proof certification, special testing should be conducted in accordance with the IEC 60079 series. By adhering to this standard, the consistency, reliability, and security of magnetic sensing devices can be significantly improved, laying the foundation for smart factories and IoT applications.