Relays and Timers

Relays and Timers are essential pieces of the automation process. Our stock of Relays and Timers includes a variety of electro-mechanical and solid-state devices with different ranges and capabilities. This variety allows our Relays and Timers to fill the needs of many applications.

Sockets & Accessories
Many accessories are also available including:

• Relay Sockets
• Fuse Modules
• Heatsinks and Thermal Pads
• Potentiometers

What are Relays and Timers?
A relay is an electrically controlled device that allows an electrical circuit to be switched on or off. The use of relays allows for one or more circuits to be controlled by a different control circuit. Timers are relays that operate on a time delay.

Where are Relays and Timers used?
Relays are an essential part of the motor control and industrial worlds. As such, they are used in many types of applications including:

• Pumps
• Industrial Controls
• HVAC Systems
• Lighting

Who uses Relays and Timers?
Anyone with a need to control an electrical circuit in an industrial setting is likely to use a relay. Some examples of industries that see widespread use of relays are:

• Industrial Control
• Heating and Air
• Water, Wastewater, and Power
• Building Control

Selecting Relays
When choosing your relays, the most important factors to consider are the amps, number of poles and throws, and coil voltage.

What are the Required Amps?
A relay’s amp rating refers to the maximum rated current. This is the highest current that a relay should be switching.

Number of Circuits and Switching Positions?
In relays, there can be multiple individual circuits (or poles) that act as the common terminal(s) that power travels through. Each circuit can have one or multiple extreme switching positions (or throws). The switching positions refer to the points where the circuit(s) can connect depending on whether the relay is energized or de-energized.

Example 1: In a single pole single throw (SPST) relay, there is one place where the power comes in and then only one place for it to go when the circuit is closed.

Example 2: In a single pole double throw (SPDT) relay, the power comes in on a single path and can connect to one of two points depending on if the relay is energized or not.

Normally Open or Normally Closed?
Relays with only one switching position (e.g. SPST) are either Normally Open (NO) or Normally Closed (NC). NO relays keep a circuit open until energized and NC relays do the opposite. NO relays are used so that energizing a relay sends power to the devices operating on that electrical circuit. NC relays are used so that energizing a relay cuts off power from the devices operating on that electrical circuit.