| Armature
| Moving part of an electromechanical relay that moves when the relay is energized and opens a set of contacts. |
| AWG
| American Wire Gauge, a wire thickness unit and system of measurement. |
| Break
| The number of separate places on a contact that open or close an electrical circuit. |
| Contacts
| The conduction part of a relay that opens and closes an electrical circuit. |
| Contact Life
| The number of cycles a contact can be opened and closed or energized. |
| Current Bar
| Conductor at the center of a terminal block that carries current from termination(s) in the terminal block to the field wiring. |
| Dropout Voltage
| The voltage level at which a circuit becomes inoperative. |
| Ferrule
| A metal sleeve that joins or helps strengthen two parts. |
| Heat Sink
| A protective housing made up of material that dissipates heat. |
| Normally Closed
| The contacts are normally closed or making contact. They open only when the relay or timer is energized. |
| Normally Open
| The contacts are normally held open. They close only when the relay or timer is energized. |
| OFF-State
| Voltage that is present in a circuit when the supply voltage to that circuit is connected but turned off. |
| Pole
| The number of completely isolated circuits that a relay can switch. |
| Pickup Voltage
| The minimum amount of voltage required to activate a circuit. |
| Pressure Plate
| Component within a terminal block for making a secure termination. |
| Ramp-Up
| The amount of time required to go from zero voltage to operating voltage in a solid-state system. |
| Reed Relay
| Two reed contacts hermetically sealed in a glass envelope. |
| Relay
| A device for switching circuits electromechanically or electronically. |
| Solenoid
| An electromechanical device typically consisting of an electromagnet and a plunger. The electromagnet causes the plunger to either move towards it or away from it, thus opening or closing a circuit. |
| Terminal Block
| A device to terminate two or more wires. |
| Throw
| The number of closed contact positions per pole. |
| Timer
| A device for switching a circuit ON or OFF based on a time delay. |
| Voltage Transient
| Voltage that spills over from one circuit to another or the residual current in a circuit. |
| Zero Switching
| Switching a relay when the voltage is near zero, typically used to prevent damage or wear from current surges. |
