A key consideration here is scalability, as the advanced safety solutions may need to be integrated with a single machine or large-scale plant systems that have interlinked production lines. This facilitates compliance with normative requirements as well as cost-effective operation. Scalable solutions can also be less costly and time-consuming to implement. The increasing demands on safety technologies have resulted in a higher level of intelligence in the solutions’ components. Quick, flexible, and safe Manufacturers need to make sure that they are protecting their staff from a machine’s moving parts. Often, structural measures such as physical guards and access covers are not sufficient, so electronic safety equipment may need to be added to help prevent staff from entering the hazardous area. With traditional safety technology, opening a guard door can trigger the contacts on the safety switch. This signal interrupts the contactor controls for the machine’s power supply via a monitoring module. As a result, the machine stops and the operator should be able to approach it with no danger. This procedure is satisfactory from the safety point of view, but is not compatible with the demands placed on today’s production systems – namely, that they provide optimal capacity utilisation along with high levels of productivity. Bringing a production system to a complete standstill and the time needed for restart it, leads to unnecessary downtime periods, and has an immediate impact on production. This is one of the reasons that operators may be tempted to change settings or resolve errors on machines that are still running. However, this will pose a risk to them if protection from injury is insufficient, whether the danger is inherent in the task itself or due to the circumvention of existing safety measures. The mandatory emergency stop button may be difficult for maintenance staff to reach quickly. A better alternative is to think about these tasks at the machine building stage and take them into account for various different modes of operation. With AC drive embedding safety technology, machine builders can effectively help protect personnel against hazards, and simultaneously increase productivity by reducing the duration of special operation modes. Wait times during power-down and restart are shorter due to the mains contactor not needing to be disconnected. Monitor motion A typical application of advanced safety functions is to assist with the safe cleaning or removal of material from a rotary press. Operators can only perform this action when the rollers move apart slowly and in a defined direction. This is why it is important to monitor both the speed and the direction of rotation, and safely switch off the machine to help protect the operator if these parameters change. The advanced safety features are also useful when the machine is first commissioned or being serviced. The operator can initiate certain machine functions and control the production process at reduced speed when the safety door is open and the enabling switch is on. In this special operation mode, the advances safety functionality, helps prevent unexpected start-up, and monitors the emergency stop and the guard lock at the same time. Advanced safety systems help reduce the number of monitoring components, which in turn helps to cut additional hardware and installation costs. This is especially true for wiring costs and space requirements in the switch cabinet. In addition, intelligent and integrated safety technology can help provide protection for operators in hazardous areas. This is because it reacts immediately to changes in the drive, and instantly stops potentially dangerous machine movements by switching off the electronic safety outputs. Some decision makers wonder whether it is worth investing in a safety relay. From the economic viewpoint, companies need a cost-benefit analysis based on the application in question to help them decide. With a smaller machine, firms can look at how operating modes will be used on a case-by-case basis and verify whether the use of a relay is appropriate. Achieving safety goals Most safety products and systems are designed to help machine and plant builders achieve their safety objectives in a cost-effective way that is also compliant with standards. Also, safety-oriented drive technology, with its additional functions, is only one element in the safety chain. The real benefit to users is derived from the way the components interact with each other. An end-to-end, information-oriented safety solution is a prerequisite for companies wanting to run their machines both safely and productively. Today’s intelligent systems help companies achieve both these goals, which until recently were difficult to reconcile with each other. The last few years have seen a constant increase in requirements for high levels of machine availability and safety technology. Today, there is an even stronger focus on the safety area with the adoption of the EN ISO 13849-1 and IEC/EN 62061 standards. This has resulted in the quality of the individual components playing a bigger role in defining or influencing the probability of machine failure. Today, companies can determine the most cost-effective safety strategy for the controller-related parts of their control systems based on the risk analysis and the resulting performance level or SIL. ? Courtesy: Rockwell Automation
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