GlobalQuestion
What is the difference between Solid-state Relays and Contact Relays?
Answer
Solid State Relays use semiconductors for no-contact operation. Solid-state Relays are not very different in operation from Contact Relays (Electromagnetic Relays). Solid-state Relays, however, consist of electronic parts with no mechanical contacts. Therefore, Solid-state Relays have a variety of features that Contact Relays do not incorporate.
Use both Relays in accordance with the intended use.
Main features of the Solid State Relay and the Contact Relay
Input characteristics
| Subject | Merit | Solid State Relay | Merit | Contact Relay (Electromagnetic Relay) |
| Noise & Surge | Yes | Nothing | Reverse-surge happen when input signal stopped |
Output characteristics
| Subject | Merit | Solid State Relay | Merit | Contact Relay (Electromagnetic Relay) |
| Number of contact poles | Normally 1a contact | Yes | Multiple contact available | |
| Load current | Allow a few times higherrash current. And have no operation zone as small load. | Need some treatment, contact reliability at small current operation at high current | ||
| Transit | Have a destruction or malfunction risks at high voltage or transit voltage | Nothing | ||
| Bounce/chatter | Yes | No bounce or chattering | Have some bounce or chattering | |
| Leak current | A fewμA and a few mA | Yes | Zero | |
| Noise/Surge | Noise occurred during theloss time operation | Surge noise occurred when the inductive load used | ||
| Arc | Yes | Nothing | Arc happen at middle and large load | |
| Zero-cross function | Yes | Available | Not available | |
| Life | Yes | No limitation | Approx a few million times |
Environmental characteristics
| Subject | Merit | Solid State Relay | Merit | Contact Relay (Electromagnetic Relay) |
| Temperature | Required the heat-sink design as self-heating of semicon device | Required the body material and change of operation mode. | ||
| Operation sound | Yes | Nothing | Contact sound occurred |
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