Single-phase solid state relay | 25 A | DC → DC | LED indication | contactless switching | GSR1-1-25DA

Solid-state relays (SSRs) and electromechanical contactors are used to perform similar functions – switching electrical circuits, controlling currents and loads in industrial or commercial systems. However, these two components differ significantly in their operating principles, longevity, speed, and reliability.

1. Operating Principle
Solid-State Relay (SSR):

Operates using semiconductors such as triacs, thyristors, or MOSFET transistors. When a control signal is applied, the semiconductors start allowing current through the relay, creating a switching action without mechanical movement.
SSR relay switches current silently and without mechanical wear.
Electromechanical Contactor:

Operates using an electromagnet that pulls or pushes an armature (moving part), thus connecting or disconnecting contacts. This switching causes mechanical movement and may generate noise (clicking sound).
Mechanical contacts wear over time due to continuous movement and contact surface wear.
SSR Advantage: Solid-state relays have no moving parts, making them more durable and reliable, especially with frequent switching.

2. Longevity and Reliability
SSR:

Since there are no mechanical parts, SSR relays are extremely long-lasting and can operate without maintenance for thousands of switching cycles. There is no risk of mechanical wear.
Contactor:

Mechanical parts (contacts) wear over time, meaning electromechanical contactors have a limited lifespan and require maintenance or replacement after a certain number of cycles.
SSR Advantage: Longevity and almost zero maintenance make SSR superior for long-term use.

3. Switching Speed
SSR:

SSR relays switch extremely fast, within microseconds. This is very useful in industrial or automation systems that require fast and continuous switching.
Contactor:

Electromechanical contactors switch slower, as the moving parts take time to engage or disengage. The switching duration is in milliseconds or longer, depending on the design.
SSR Advantage: Solid-state relays are much faster and can be used in applications where switching speed is critically important.

4. Noise
SSR:

Since SSR relays have no moving parts, they operate completely silently.
Contactor:

Electromechanical contactors generate noise during switching due to the electromagnetic coil and movement of contacts. This noise may be undesirable in quiet environments.
SSR Advantage: SSR relays operate silently, making them more suitable for sensitive environments, such as hospitals or offices.

5. Current Switching Capability
SSR:

SSR relays are best suited for small to medium loads. They have some heat generation issues at higher currents and often require cooling elements (heatsinks).
Contactor:

Electromechanical contactors are ideal for switching large currents because mechanical contacts can easily handle high loads without using semiconductors, which need additional cooling.
Contactor Advantage: Contactors can handle larger loads and are more suitable for high-current switching.

6. Power Consumption
SSR:

SSR relays require less power for control since they lack electromagnetic components and use very small control currents.
Contactor:

Electromechanical contactors require a higher current to energize the coil, especially when maintaining the switched state for a long time.
SSR Advantage: SSR relays consume less power during the switching process.

7. Protection and Reliability
SSR:

SSR relays incorporate zero-crossing technology (zero-crossing switching), which reduces electrical noise and protects against current surges. However, they are sensitive to overheating and overloading, requiring thermal protection.
Contactor:

Contactors are more resistant to electrical surges and short-term overloads, as mechanical contacts naturally withstand higher surges, but they tend to wear out and lose efficiency over time.
Contactor Advantage: Mechanical contactors are more resistant to large currents and surges, but SSR protection mechanisms are more effective in the long term.

8. Cost
SSR:

SSR relays are generally more expensive than traditional contactors due to the more complex semiconductor technology and their longevity.
Contactor:

Electromechanical contactors are cheaper, as their manufacturing is simpler, but they often require additional maintenance or replacement after prolonged use.
Contactor Advantage: Contactors are cheaper, but long-term maintenance costs can diminish their initial cost advantage. 

This product is marked with the CE label, which confirms that it complies with all applicable European Union directives and regulations. CE marking is not just a formality – it is an important indicator of quality and safety, ensuring that the product has been properly assessed, tested, and can be safely used throughout the EU market.

CE certification means that the product has been evaluated according to the main criteria:

Safety requirements – ensures that the product does not pose a risk to the user or the environment
Electromagnetic compatibility (EMC) – the device does not interfere with other equipment and is resistant to external disturbances
Environmental standards – complies with current ecological and material usage requirements
Operational reliability – the product is suitable for long-term use according to its intended purpose

CE marking allows this product to:

be legally supplied and used in all European Union countries
ensure a high level of quality and safety
be used in residential, commercial, and industrial environments

The CE mark is a declaration of the manufacturer’s responsibility, confirming that the product complies with all applicable standards and has been assessed according to EU legislation.

What does this mean for you as a buyer?

Safe use in everyday activities
Reliable performance and reduced risk of failure
Compliance with EU standards and requirements
Suitability for professional solutions