This Eaton ESR5-NV3-30 safety relay monitors electric signals in safety devices for emergency shut-off. It has DIN rail mounting for securing to an equipment rack. It is a main unit allowing for four safe outputs. It has a double-pole, single throw, normally open contact form, with coil voltage of 24 VDC, a maximum contact current of 3 amp, and a contact voltage of 230 VAC. This is a dual channel relay for continued operation in the event of a single circuit failure. It has plug-in screw terminals for easy replacement. This safety relay is suitable for use with emergency stops, rope pulls, two-hand control stations, gate enabling devices, and safety switches, among others.

*H is height, the vertical distance from the lowest to highest point; W is width, the horizontal distance from left to right; D is depth, the horizontal distance from front to back.

Relay switches (also called an electrical relay or an electrical relay switch) use a small amount of power to control a larger source of power connected to electrical devices such as car motors, computers, and lighting installations. A basic relay switch has a control circuit with an electromagnetic coil and a load circuit with contacts and a lever. When current flows into the relay switch, it moves through the coil and a magnetic field is created, which causes the lever in the load circuit to move between contacts, either turning the device on or off. In a normally open (NO) relay switch, when power is supplied to the relay, the load circuit is closed and the power source connected to the relay is turned on. In a normally closed (NC) relay switch, when power is supplied to the relay, the load circuit is open and the power source connected to the relay is turned off. In other types of relay switches, non-moving parts such as transistors or semiconductors can be used as the control circuit to operate the switching mechanism. Relay switches can be controlled with an external switch, such as a light switch, or they can be connected to an automatically switched power source, such as a car ignition. One relay can operate multiple switches, and multiple relays can be operated with a single switch, with each relay operating independently from the other relays in the system.

Eaton manufactures electrical, hydraulic, and mechanical power equipment. The company, founded in 1911, is headquartered in Dublin, Ireland.