PLC - Deadman Switch

Deadman Switch

A deadman switch, sometimes referred to as an emergency stop switch or a deadman’s switch, is a safety device that allows a machine or process to be stopped immediately in the case of a danger or emergency.

A deadman switch can be used as an input device in a Programmable Logic Controller (PLC) to initiate an emergency stop function.

How Deadman Switch Works?

Input Device

A physical input device with rapid and simple activation is the deadman switch. It may be in the shape of a toggle switch, push button, or various kinds of safety switches. Typically, the switch is meant to be manually grasped or manipulated by the user, necessitating constant pressure or engagement.

PLC Input Connection

The PLC’s digital input channel is linked to the deadman switch. Wiring is used to make the connection between the switch and the PLC’s input module.

Programming PLCs

The deadman switch input channels has a particular input address or bit assigned to it in the PLC program. The input channel’s condition is continuously monitored by the program.

Emergency Stop Function

The deadman switch signals the requirement for an emergency stop to the PLC input channel when it is engaged or activated. This input signal is intended to cause the PLC software to activate the emergency stop feature.

Emergency Stop Technique

Emergency stop actions may include deactivating actuators, closing valves, stopping motors, or halting any potentially dangerous activity. To ensure a safe & controlled stop of the machine or process, the PLC is programmed with the precise actions & sequence of the emergency stop.

Safety Monitors and Surveillance

The deadman switch input’s condition is continuously observed by the PLC. The PLC software ought to initiate the emergency stop function in the event that the switch is released (or) disengaged, signifying a lack of control or operator presence, in order to guarantee safety.

By providing a way to swiftly and efficiently stop potentially hazardous processes, the deadman switch added to a PLC system contributes to increased safety. It lowers the possibility of mishaps or injuries by enabling operators to respond quickly in conditions of emergency.

Making sure the deadman switch is wired, installed, and maintained correctly is important. To ensure the deadman switch’s dependability and efficacy as a safety device, routine testing and testing of the circuitry that’s connected with it are required.

Application of Deadman Switch in PLC

Deadman switches are utilized in a wide range of industrial environments, including manufacturing plants, construction sites, and transportation networks.

Overall, PLC deadman switches are important components of safety systems, assisting to prevent accidents & protect workers in the industrial settings.