Relays are electrical switches with internal mechanical switching mechanisms that are operated by an electromagnet coil. The coil activates the relay contact when it is open.
Why Use a Relay Device?
Relays are used to enable one circuit with a lower current to control another circuit or circuits with a higher current. Here are the benefits of using relays:
- The control switch can be connected to the relay using thinner cables, saving space, weight, and cost.
- Relays reduce voltage loss by routing power to an appliance over the shortest possible distance.
- Only a heavy-gauge cable is required to connect the device to the power source via the relay.
Why Use a Relay in Your Car?
Relays offer numerous advantages in automotive applications. They provide a cost-effective and lightweight alternative to high-current switches or cables. Relays can be placed anywhere in the vehicle for efficient power transfer and can be used to control various circuits, such as headlights and electric motors.
Understanding the Electrical Specifications of a Relay
Basic relays have electrical ratings for both the coil and internal switching contacts. The coil voltage rating refers to the voltage needed for the coil’s correct operation. The relay’s switching circuit also has voltage and ampere ratings, which should not be exceeded. Double-throw relays have two electrical specifications: one for the normally open terminal and another for the normally closed terminal.
Why Do Relays Use Protection Devices?
When a relay is switched off, the coil can de-energize and cause a voltage spike. To mitigate this, diodes or resistors are sometimes added to the coil of a relay to reduce voltage spikes that could potentially damage sensitive components. Diodes are more efficient in eliminating voltage spikes, while resistors are more durable. The choice of protection depends on the sensitivity level of the components within the control circuit.
For nearly half a century, Swartz Engineering has been at the forefront of industry safety. They are a family-owned company specializing in power distribution for the electrical industry. They are the leading manufacturer of Type 76 DC relays. It is the most widely accepted protective overcurrent device used in the transit industry today.