What do the numbers on a relay mean?
What do the numbers on a relay mean?
Numbers of a Relay 87 and 87a are the two contacts to which 30 will connect. If the coil is not activated, 30 will always be connected to 87a. Think of this as the relay in the Normally Closed (OFF) position.
Can you put a 4 pin relay in backwards?
Relays can’t be inserted backwards. The ones you can put in two ways, will work either way.
Why use a relay instead of a switch?
While a relay does add an extra step to the switching process, the main advantage is that you can leave the actual switching of high-power circuits for things like off-road lights or air compressors in the engine compartment, and control that switching with a much smaller amperage circuit that energizes the relay’s …
What’s the difference between a 4 pin and 5 pin relay?
The difference between a 4 and 5 pin relay is that a 4 pin relay is used to control a single circuit, whereas a 5 pin relay switches power between two circuits. 4 pin relays use 2 pins (85 & 86) to control the coil and 2 pins (30 & 87) which switch power on a single circuit.
Does a relay need to be grounded?
The relay must be on the ground side of the load when the voltages above the coil are hot. The case should be grounded. The relay can be on either side of the load for hot switch voltages that are lower than the coil.
What is terminal 87a used for on a relay?
The relay is a remote-controlled switch that works on the principle that a tiny amount of current can be used to energize a little internal electromagnet….Understanding Relays, part 2: DIN numbers and different types of relay.
| Terminal | Which Circuit? | Definition |
|---|---|---|
| 87a | High current (load) | Output to other device, normally closed, pulled open when coil is energized |
What happens if you put a relay in backwards?
Often seen as a quick fix, using the wrong relay for the application can cause inadvertent voltage spikes. Many relays, if installed for the wrong application, could and will cause a short (Internal Relay Circuit) and most likely cause functionality issues or even damage to the vehicle computer systems.
Does it matter which way you put a relay in?
The orientation of the relays shouldn’t really matter. On the bottom of the relay you will see the numbers 85, 86, 87 & 30 marked. 85 & 86 are the terminals connected to the relay coil (the relay control circuit) and 87 & 30 are the terminals connected to the switch contacts (the relay load circuit).