1. Service life and stability

In fact, the life of the mechanical contact determines the life of the mechanical relay.Since there is no mechanical contact inside SSR relay, the service life of SSR relay will not be shortened due to strain, aging, corrosion and adhesion of contact.At the same time, the solid state relay has no mechanical moving parts inside (such as springs and reeds), so there will be no contact rebound and poor contact of moving parts.

Solid state relays have good impact resistance, impact resistance and corrosion resistance due to non-contact construction and resin enclosure protection.Solid state relays have a wider range of applications than EMR. For example, humidity has little effect on solid state relays, only slightly reducing their insulation performance. However, electromagnetic relays are very sensitive to humidity.

In a word, the life span of solid state relay is 50-100 times that of electromagnetic relay, and the reliability of solid state relay is far better than that of electromagnetic relay.

 2.Cost

The initial purchase cost of solid state relays is higher than that of electromagnetic relays.However, considering other costs (such as integrated life, inspection and maintenance costs, losses and inefficiencies due to relay instability or failures, etc.), the average cost of using solid-state relays is much lower than that of electromagnetic relays.

In addition, in some applications, additional costs are required to prevent contact vibration and poor contact of mechanical relays.

3.Efficiency

The operating frequency (or switching rate) of solid-state relays is several to tens of times that of electromagnetic relays, which enables SSRS to be used in devices that require high efficiency.In addition, SSR USES semiconductors as the signal transmission medium, so SSR can be compatible with computer control systems without the need to add additional circuits and equipment, which EMR cannot do.

The response time of SSR relay is far lower than that of mechanical relay, and the control power of SSR relay is also lower than that of EMR relay, which makes EMR unsuitable for devices requiring short response time.Low control.In some special applications that require a low power factor, the switch must be stable and free from vibration, so EMR relays cannot be used.

4. Electromagnetic radiation

The mechanical structure enables the mechanical relay to generate a large number of electromagnetic interference (EMI) signals during switching.Without additional protective circuits, these interference signals may adversely affect electronic equipment and the power grid.Strong electromagnetic interference can even cause harm to the human body.

In contrast, solid state relays have good electromagnetic compatibility (EMC).Solid state relay with zero crossing function can reduce the influence of external interference on SSR and the interference signal generated by solid state relay itself.

Therefore, if applications require low emi, it is recommended that only solid state relays be used.

5. Working mode

Solid state relay has various internal circuits, which can be designed flexibly according to actual needs.Through the combination of internal components, the solid state relay can realize various control of the output circuit according to different states of control signal and power supply.

However, electromagnetic relays can only switch loads asynchronously, that is, the state of the switch is controlled only by the control signal and is independent of the power signal.The solid state relay can be controlled synchronously.Of course, solid-state relays have more action modes, such as:

1) asynchronous mode

2) synchronous mode

3) voltage zero or peak synchronous mode

4) phase Angle mode

5) pulse mode