1-minute to understand Industrial Relay Contact Types and Application

1-minute to understand Industrial Relay Contact Types and Application

Have you ever felt confused by relay contact symbols when designing industrial automation systems? Or hesitated during selection, unsure which contact type best fits your project? Don’t worry—this article will take you on a deep dive into Industrial Relay Contact types, symbols, and their specific roles and advantages in industrial applications. By mastering these essentials, you’ll boost your design efficiency and avoid the risks that come from choosing the wrong contacts.

As a factory specializing in industrial relays, we understand the high demands B2B customers place on product performance and reliability. This article combines real-world application scenarios to help you understand the features of different relay contacts, empowering you to make smart decisions. If you’re planning to purchase or upgrade your relay systems, feel free to contact us for expert Industrial Relay Contact Selection advice.


Basics of Industrial Relay Contacts

First, what is an Industrial Relay Contacts? Simply put, relay contacts are metal points inside a relay that open or close a circuit. When the relay coil is energized, the contacts move according to their design, switching the external circuit on or off.

The working principle of relay contact is based on electromagnetic force, enabling circuit isolation and control. They play crucial roles in industrial automation, handling control, signal conversion, protection, and more. Understanding the basics of relay contacts is the first step to mastering relay applications.

Industrial Relay Contact6

Detailed Explanation of Relay Contact Symbols

Recognizing relay contact symbols is essential for design and selection. International standards such as IEC 60617 and GB/T 4728 help engineers accurately understand relay functions.

Common relay contact symbols include:

  • Normally Open Contact (NO, H type): Default is open; closes when the coil is energized.
  • Normally Closed Contact (NC, D type): Default is closed; opens when the coil is energized.
  • Changeover Contact (CO/Z type): Contains both NO and NC contacts, allowing circuit switching.
  • Force-Guided Contact: Used in safety-critical applications, ensuring reliable contact movement.

Contact symbols also indicate rated voltage, current, insulation level, and other parameters for easy reference during selection.

Classification of Relay Contact Types and Application Scenarios

Different relay contact types suit different industrial applications. Here are the main types and their typical uses:

  • Power Relay Contacts: Ideal for high-power control, such as starting and stopping motors.
  • Signal Relay Contacts: Used for low-power signal switching, common in sensors and control signals.
  • Time Relay Contacts: Enable delayed control, widely used in automated processes.
  • Safety Relay Contacts: Feature force-guided design, ensuring reliability in safety circuits.

These contacts are indispensable in industries such as energy, manufacturing, lifting equipment, automatic doors, and emergency systems.

Specific Roles and Advantages of Different Contacts in Industrial Applications

Let’s take a closer look at the specific roles and advantages of each contact type in industrial settings:

Contact TypeSpecific RoleAdvantages
Normally Open (NO)Controls device startup, alarm signal outputFast response, ideal for circuits that close when energized
Normally Closed (NC)Used in safety circuits, emergency shutdownDefault closed, ensures safety by preventing accidental start
Changeover (CO)Switches between circuits in complex systemsVersatile, space-saving, suitable for multi-way control
Force-Guided ContactUsed in elevators, robotic arms, high-safety areasHigh safety, prevents malfunction due to mechanical failure

Additionally, contact materials like silver-tin oxide (AgSnO2) enhance durability and corrosion resistance, extending service life. Choosing the right contact configuration and material can significantly improve system reliability and efficiency.


Mastering Relay contact symbols, types, and their application advantages is a vital step toward enhancing your industrial automation system design. Each contact type has unique strengths, and choosing the right relay products contact ensures your equipment runs safely and reliably.

As a professional industrial relay manufacturer, we are committed to providing high-quality Industrial Relay products and expert technical support. Whether you need standard products or custom solutions, we welcome your inquiries.

Our factory not only offers a wide range of industrial relays but also provides customized solutions tailored to your needs. Whether you’re choosing among Relay Contact Types or designing a complex system, we’re here to offer expert advice. Don’t hesitate—contact us today and let us help you find the perfect relay products solution for your industrial projects!

FAQ

How long is the contact lifespan?

The lifespan depends on the material and load type, but usually exceeds hundreds of thousands of cycles.

How do I recognize contact symbols?

Understanding international standard symbols is key—see sections above for detailed explanations.

How can I avoid misoperation during selection?

Choose relays that comply with standards and the correct contact configuration, and seek professional technical support.