How Many Types of Relays Are There?
2 Answers
There are 7 types of relays, categorized as follows: 1. By working principle or structural characteristics: solid-state relays, reed relays, polarized relays, etc.; 2. By size: micro relays, ultra-small micro relays, small micro relays; 3. By load: micro-power relays, low-power relays, medium-power relays, etc.; 4. By protective features: sealed relays, enclosed relays, open relays; 5. By operation principle: electromagnetic relays, induction relays, rectifier relays, etc.; 6. By physical quantity measured: current relays, impedance relays, frequency relays, etc.; 7. By function in protection circuits: starting relays, measuring relays, signal relays, etc.
I've been driving for over 30 years and have encountered various relay failure issues. There are quite a few types of relays in cars, the most common being electromagnetic relays—those devices that use small currents to control large currents, like when you turn on the headlight switch, they handle high loads. I've replaced them several times; it's not too difficult, but you need to identify the right one. Next are solid-state relays, which are more common in modern cars—they have no mechanical parts, so they don’t wear out, making them ideal for electronic controls like the ECU system. Time relays are also quite important, such as when the wipers have a delay function or the headlights automatically turn off. Thermal relays are used for overload protection—if the cooling fan fails, it’s often because the thermal relay has blown. Miniature relays are compact and installed in tight corners, making them hard to spot. Overall, in my experience, these are the main types, each corresponding to different car functions. If they fail, it can easily cause flickering lights or prevent the car from starting. Regular maintenance can help avoid trouble, but if they do fail, I usually go to the 4S shop to get them replaced.
