Contents
How do I choose a relay rating?
An easy way to determine the limit of a relay is to multiply the rated Volts times the rated Amps. This will give you the total watts a relay can switch. Every relay will have two ratings: AC and DC. You should determine the AC watts and the DC watts, and never exceed these ratings.
Are relays used on large or small loads?
Relays are generally used to switch smaller currents in a control circuit and do not usually control power consuming devices except for small motors and Solenoids that draw low amps.
How much current does a relay coil need?
The coil of a relay passes a relatively large current, typically 30mA for a 12V relay, but it can be as much as 100mA for relays designed to operate from lower voltages. Most ICs cannot provide this current and a transistor is usually used to amplify the small IC current to the larger value required for the relay coil.
What is 87a on a relay used for?
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 |
How to determine the limit of a relay?
Volts x Amps = Watts – Never Exceed Watts! An easy way to determine the limit of a relay is to multiply the rated Volts times the rated Amps. Every relay will have two ratings: AC and DC. You should determine the AC watts and the DC watts, and never exceed these ratings.
What makes a reed relay faster than an electromechanical relay?
Dry reed relay: Current through the coil creates a magnetic field which draws the two reed contacts together. Because of the smaller, less massive contacts and the different actuating mechanism, a reed relay can switch about 10 times faster than an electromechanical relay with equivalent ratings.
What is the current capacity of a 12 volt relay?
Typically 12V for passenger vehicles and small craft but also available in 6V for older vehicles and 24V for commercial applications (both auto and marine). This is the current carrying capacity of the high current circuit (s) and is normally between 25A and 40A, however it is sometimes shown as a dual rating on changeover relays e.g. 30/40A.
How do you determine the watts of a relay?
An easy way to determine the limit of a relay is to multiply the rated Volts times the rated Amps. This will give you the total watts a relay can switch. Every relay will have two ratings: AC and DC. You should determine the AC watts and the DC watts, and never exceed these ratings.