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Functional safety is a major issue when it comes to the safety-related requirements of machines and plants.
The safety-relevant parts of the protection and control devices must function correctly and, when a fault condition develops, must ensure that the plant or system either remains in a safe state or is brought into a safe state. As a result of the high-speed drives that are generally used if there is a system malfunction on a machine this can result in potentially hazardous motion. The integrated safety technology used in motion control systems essentially provides protection against this hazardous motion. The highly effective safety functions are used to monitor velocity or speed, zero speed and also position. These monitoring functions are required if personnel can access hazardous zones of machines and plants — e.g. when setting-up. However, also when testing and in production, in addition to providing effective personnel protection, they also offer a high degree of protection for tools, materials and machines.
Safety solutions available today can detect critical situations and initiate appropriate measures in just a fraction of second — at the speed of light. These can integrate into standard control architectures, curtailing downtime by allowing operators to diagnose machine stoppages more intelligently - especially nuisance trips - and quickly get production up and running again.
Overview
These solutions are built around a harmonized series of products that all fit together. These products can be used in the automation and drive environment to implement innovative solutions to provide the required level of safety for plants and systems. It is important to note that integrated safety solution is an integral part of our standard automation environment.
The individual components can safely communicate via standard buses. Therefore offering innovative safety technology, which when it comes to flexibility, diagnostics and standardization, is certainly on a par with standard automation. The range products include for example, safety-relevant low-voltage controls and sensors, fail-safe PLC controllers, fail-safe CNC controls and variable-speed drives with integrated safety functions.
Standard PROFIBUS and AS-Interface buses can be used for both normal and safety-relevant communications along one and the same bus cable. This results in significantly lower installation and engineering costs. The PROFIsafe profile for PROFIBUS DP and ASIsafe with the safety monitor for AS-Interface form the basis. The functional safety of the components fully comply with the safety relevant requirements of the appropriate Regulations and Standards and are certified by acknowledged bodies.
Benefits
Highly cost effective
Integrated and seamless from the sensor through the evaluation unit down to the actuator
High cost-effectiveness
Reduced hardware and installation time and costs
Plants and systems can be simply coupled
Using safety-relevant communications via standard field buses
Effective, fast diagnostics To secure a high degree of availability for machines and plants
Safe programmable logic (SPL)
Safety enabled sensors and actuators can be directly connected to the safety relevant I/O of the control system when using safe programmable logic. External evaluation units are not required and signals are safely evaluated in the software. The associated logic operations are redundantly implemented in the NC and in the integrated PLC.
Safe brake management
The safe brake management function comprises a safe braking signal and a cyclic braking test. The safely controlled and tested brake in conjunction with the safely-monitored drive results in a redundant holding system to prevent vertical axes falling. The reliability of a mechanical brake is an essential component when it comes to providing protection against vertical axes falling. The brakes that are generally used today are not safety-relevant components. A safe brake function is obtained by integrating the standard brake (a component that has been well-proven in the field) into the safety integrated concept. The brake is safely and electrically controlled in accordance with Category 3 (EN 954-1). It is controlled through two channels, P/M-switching (Plus/Minus). The safe brake test cyclically checks whether the expected holding torque is generated. Faults and errors in the control and in the mechanical braking system can be identified using these extended test procedures.
Safety-related communications via a standard bus
The safety-relevant sensors and actuators can be directly connected via the fail-safe PROFIsafe I/O. This distributed I/O is connected through the standard PROFIBUS field bus with the PROFIsafe profile.
Integrated acceptance test
When a machine is commissioned all of the safety-relevant functions of the electric drives must be tested in the form of an acceptance test. The test results must then be appropriately documented. This procedure applies to all electric drives no matter whether the safety functions are integrated in the controls and drives or whether external monitoring devices and equipment are used. This integrated acceptance test provides the OEM with a tool that he can use to semi-automatically carry-out this test with operator prompting. In addition to saving valuable time, this tool stands out as a result of its prompted test procedure and the fact that trace functions can be automatically configured. The automatically generated acceptance report proves the quality of the functional safety of the machine — both for the OEM as well as for the company that actually operates the machine.
Safe, practical, cost effective Motion control systems with integrated safety
A new generation of Motion control system offers the optimum solution for the widest range of machines for specific industry sectors. These systems help manufacturer to increase their productivity and at the same time their quality. It is integrated in the electronics and software of the control systems and drives and offers completely new possibilities as it is integrated and is part of a seamless total system. Just like in an automobile where electronics and software provide effective safety functions — e.g. airbags, ABS and electronic stabilization systems — Safety Integrated helps to reliably and quickly protect machine tools and production machines from hazards. With Safety Integrated, machines and systems can be operated in-line with standard procedures — but at the same time are equipped with highly effective safety functions.
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Pradeep Karnik
Pravin Panchagnula
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