Reed relay is a key component in electronic circuits, and its reliability is directly related to the stability and efficiency of the entire system. Compared with traditional electromagnetic relays, reed relays have unique advantages, especially the sealed design of their contacts, which significantly improves their resistance to environmental factors. Not troubled by oxidation or contamination, reed relays can demonstrate extremely high reliability in the right application. However, although they technically have the potential for long-term stable operation, in actual applications, their performance is often not fully utilized and even suffers unnecessary damage due to a lack of in-depth understanding of their working principles and usage conditions.
In circuit design, ensuring that the contacts of the reed relay are protected from damage is the key to extending its service life and improving system reliability. Contact damage is usually caused by high current or high power surges, which is extremely common due to incorrect design or usage conditions. The design specifications of reed relays include maximum current, voltage and power indicators, which are important parameters that must be considered during the design stage. Proper understanding and application of these parameters is the basis for avoiding premature contact damage.

For power supply current limiting protection measures, simply relying on the current limiting function of the power supply is not enough. This is further complicated by the fact that the current limit response takes time and there is often a capacitive load at the output of the power supply. In contrast, current limiting through resistors is a more reliable method. Especially when facing the inrush current generated when charging a capacitive load, or the high inrush current generated when a capacitor is discharged, the use of resistor current limiting can effectively reduce damage to the reed relay. For example, when a 0.1μF capacitor is discharged at a voltage of 10V and a resistance of 0.1Ω, the resulting inrush current, although short-lived, is strong enough to cause significant damage to the reed relay.
In addition, as the voltage increases, the impact of the inrush current on the reed relay will also increase exponentially. This is particularly noteworthy when performing high-voltage testing or handling high-voltage cable discharges. The energy stored in a capacitor is proportional to the square of the voltage, which means that when the voltage increases from 10V to 1000V, the energy stored in the capacitor increases 10000 times. Such extreme energy release not only poses a serious threat to the reed relay, but also challenges the stable operation of the entire electronic system.