Both sides previous revision
Previous revision
Next revision
|
Previous revision
|
electrical:relay [2017/07/08 23:37] frater_secessus [Relays] |
electrical:relay [2018/01/11 14:55] frater_secessus [Relays] |
====== Relays ====== | ====== Relays ====== |
| |
Electrical relays are devices used to **turn relatively heavy loads on/off**. They are //triggered by small amounts of power// from an external source (usually a switch operated by the user) but //can pass larger amounts of power// to the load. This reduces the cost and physical requirements of the switch and can help automate some processes. | Electrical relays are devices used to **turn relatively heavy loads on/off**. They are //triggered by small amounts of power// from an external source (usually a switch operated by the user) but //can pass larger amounts of power// to the load. This reduces the cost and physical requirements of the switch and can help automate some processes. |
| |
A typical setup looks like this: switch (and house power) --> relay --> load | A typical setup looks like this: switch (and house power) --> relay --> load |
| |
The most common relay campers are exposed to is the solenoid for [[electrical:12v:alternator|charging house batteries from the coach's alternator]]. When the vehicle is turned on power activates the solenoid and connects the house and vehicle electrical systems. | The most common relay campers are exposed to is the solenoid for [[electrical:12v:alternator|charging house batteries from the coach's alternator]]. When the vehicle is turned on power activates the solenoid and connects the house and vehicle electrical systems. |
| Relays are also useful for powering loads from [[electrical:12v:lvd|LVD]] or [[electrical:solar:charge_controller|Charge Controller]] LOAD outputs. This allows powering larger loads than the controller is rated for. |
| |
Relays are also useful for powering loads from [[electrical:12v:lvd|LVD]] or [[electrical:solar:charge_controller|Charge Controller]] LOAD outputs. | Common uses: |
| * battery isolation when [[electrical:12v:alternator|alternator charging]] |
| * [[electrical:12v:lvd|low voltage disconnect (LVD)]] |
| |
===== normally open vs normally closed ===== | ===== normally open vs normally closed ===== |
| |
Relays come in two basic types: | Relays come in two basic types: |
| - **Normally Open (NO)** - the output circuit is open/incomplete when the relay is resting. No power flows. The controlled device is **off** until the relay is triggered. //This is usually the default.// |
- **Normally Open (NO)** - the output circuit is open/incomplete when the relay is resting. No power flows. The controlled device is **off**. //This is usually the default.// | - **Normally Closed (NC)** - the output circuit is closed/complete when the relay is resting. Power flows. The controlled device is **on** until the relay is triggered. |
- **Normally Closed (NC)** - the output circuit is closed/complete when the relay is resting. Power flows. The controlled device is **on**. | ===== latching relays ===== |
| Normally it takes power from the trigger source to operate the relay. A latching relay, however, moves from position to position and locks there even when power is removed. |
| |
| |
| |