Safety Relays
Safety relays are control logic devices that monitor safety inputs and control safety outputs in industrial automation and machinery applications. In the case of a safety input or failure, safety relays enable a safe state to be reached on a machine. This is accomplished through redundant internal circuits and self-checking logic. Standard relays don’t have redundant circuits and self-monitoring to ensure that they operate in the event of a failure. Safety relays are used to prevent harm to a person or equipment.
A safety relay will monitor a safety device and if necessary will safely shut down the machine or equipment when the safety device is activated. Safety relays are used in applications such as emergency stops, safety gates, safety interlock switches, and two-hand control stations. Safety relays are designed to meet international safety standards, so machines can be certified to specific Safety Integrity Levels (SIL) and Performance Levels (PL) that the safety regulations require.
Safety relays are also referred to as safety controllers or safety modules. Many of the features of safety relays include timer functions, diagnostic functions, monitored feedback loop, monitoring of the safety function, and the capability to connect to a safety PLC. Safety relays can also connect safety devices in series and are designed to reduce the wiring cost by safely connecting multiple safety inputs to one safety relay input.
ABB Safety Relays
Eaton Safety Relays
IDEC Safety Relays
Littelfuse Safety Relays
Phoenix Contact Safety Relays
Schneider Electric Safety Relays
Weidmuller Safety Relays
FAQs
What is a safety relay?
A safety relay is a control device that monitors safety inputs like emergency stops and interlocks and reliably de-energizes outputs to bring machines into a safe state when required.
How do safety relays differ from standard relays?
Safety relays have redundant internal contacts and self-monitoring logic designed to meet safety standards, whereas standard relays do not provide the same level of diagnostic coverage or fail-safe behavior.
What types of safety devices can be connected to a safety relay?
Common safety devices include emergency stop buttons, safety light curtains, safety door switches, two-hand control devices, and safety mats.
What safety levels do safety relays support?
Safety relays help systems achieve required Safety Integrity Levels (SIL) and Performance Levels (PL) defined in functional safety standards for machines and processes.
Where are safety relays used?
Safety relays are used in manufacturing lines, packaging and processing machinery, robotics platforms, material handling systems, and any automated environment requiring safety monitoring and rapid response.
Safety Relays
In the event of a hazard, safety relays can help reduce the risk to a more acceptable level. They are commonly designed to be used in conjunction with other safety relays to increase the functionality and safety levels in work environments. The design and functionality of these relays is similar to regular relays, with a few exceptions. Like a common relay, safety relays use contacts that can be opened or closed. However, they also have the ability to evaluate and then control outputs based on those evaluations. If installed correctly, a safety relay will continue to function if a fault in a device occurs or if a fault is caused by a sensor. The redundant design features of safety relays allow for wiring errors, while still providing proper safety function.
It is very common to see safety relays being used around industrial machinery where safety is critical. Areas such as an industrial manufacturing plant environment, where there are a lot of motors, machinery and conveyors all operating simultaneously. Some of the devices that safety relays will be used with are emergency stops, three position devices, safety gates, pressure sensitive mats, contact strips, foot operated switches and time delay scenarios. Safety relays are tested much more vigorously than normal relays and have a much lower failure rate. The contacts are designed so that they can be completely disconnected, breaking both sides of the power connection as opposed to just one, like many normal relays.