Relay Arcing Risks and Mechanism
Relays are widely used switching components in electrical and electronic systems. When switching inductive loads, arcing occurs at the relay contacts. This arc not only erodes the contact surface—leading to increased contact resistance, overheating, and even contact welding—but also significantly shortens relay service life. For applications such as smart home devices, power supplies, and industrial control systems, relay arcing directly impacts circuit reliability and safety.
When a relay opens, the stored energy in the inductive load releases as a high-voltage transient pulse across the contacts, which easily triggers arcing. Over time, this accelerates relay degradation, malfunction, and circuit failure. Therefore, effective relay arc suppression and circuit protection design has become a critical challenge for engineers.
Relay Protection Solutions in Smart Home Panels
In smart home panels, relays are subject to long-term and frequent operation, especially in scenarios involving AC input and load switching. Traditional MOVs (Metal Oxide Varistors) are bulky and not suitable for miniaturized smart terminals. In contrast, the Boarden CMS Series multilayer chip varistors adopt advanced ceramic multilayer technology, offering small size, high reliability, and fast response. They are an ideal replacement for conventional MOVs, meeting both compact packaging and stable surge protection requirements in smart home systems.
Key protection strategies include:
- AC Input Protection: Place CMS varistors at the AC input to suppress surge interference while meeting SMD size constraints.
- MOSFET Protection: Add CMS varistors at the switching transistor to prevent overvoltage stress and enhance MOSFET reliability.
- Relay Arc Suppression: Connect CMS varistors across relay contacts to clamp transient voltage, preventing arcing and contact welding.
- Coil Protection: Add CMS varistors across relay coils to accelerate demagnetization and ensure complete contact release.
Relay Circuit Protection in Power Supply Applications
In LED drivers, induction cookers, and similar applications, both input and output relays face arc-related risks.
- Input Relay Protection: Input relays protect NTC thermistors during startup, but switching high-power loads often generates arcs. By paralleling Boarden CMS chip varistors across relay contacts, transient energy is quickly absorbed, preventing contact erosion and ensuring stable power efficiency.
- Output Relay Protection: In non-isolated power supplies, output relays disconnect the driver from the LED board. Without protection, contacts may carbonize under high voltage, increasing resistance, heat, and eventually welding. By deploying CMS varistors across the contacts, arc events are significantly reduced, contact reliability is maintained, and leakage currents causing LED “ghost glow” are eliminated.
Advantages of Boarden CMS Chip Varistors
Boarden Electronics has independently developed the CMS Series multilayer chip varistors, which demonstrate significant advantages in relay arc suppression and circuit protection:
- Miniaturized Design: Much smaller than conventional MOVs, ideal for compact PCBs in smart home, lighting, and power applications.
- Fast Response: Nanosecond-level clamping of surge voltage, effectively suppressing relay arcing.
- High Reliability: Proven through high-temperature, overload, and surge testing, ensuring stable performance in harsh environments.
- Wide Model Range: Available from 0603 to 2220 sizes, covering low- to high-voltage applications in smart home, automotive electronics, and industrial power systems.
Comparative testing shows that CMS varistors effectively reduce relay bounce, lower surge frequency and energy, and significantly extend relay lifetime.
Application Value
With the rapid growth of smart home systems, LED drivers, and renewable energy power supplies, the demand for reliable relay arc suppression continues to rise. Traditional MOVs are no longer sufficient to meet the requirements of miniaturization and high performance. The Boarden CMS Series chip varistors, with their compact size, fast response, and proven reliability, provide engineers with a superior solution.
Looking forward, Boarden Electronics will continue innovating with CMS products to deliver safer and more reliable relay protection solutions, helping the smart home, lighting, and power industries address the challenges of surges and arc suppression.
