SIL Speed Protection Systems
ISTEC International, SPEED Monitoring
Overspeed protection systems have one of the most important functions regarding safety measures for rotating machinery. As such, these systems require advanced safety functions to detect overspeed and excessive acceleration.
Rotating machinery is some of the most critical equipment in industrial processes. Their condition monitoring and protection requires advanced systems. The maximal availability and safety of the critical assets can only be guaranteed by a responsive and flexible service, delivered by vibration and speed sensing experts.
Overspeed protection systems have one of the most important functions regarding safety measures for rotating machinery. As such, these systems require advanced safety functions to detect overspeed and excessive acceleration situations, and act accordingly to prevent damage and downtime. However, advanced should not be mistaken for complexity, as complexity does not necessarily mean that the system is “better”. The more functions an overspeed protection system has, the more complex it becomes, and this does not necessarily equate to being more advanced. There are 4 reasons why overspeed protection systems should not be overly complex.
Core of overspeed protection
Leading machine standards such as the API 670 and the IEC 61508 have one main requirement for rotating machinery: to be equipped with a state-of-the-art overspeed protection system. The core of overspeed protection is to detect overspeed and/or excessive acceleration situations and initiate a trip relay as required. Any other function(s) is classified as an add-on and are not a requirement to adhere to machine safety guidelines.
Complex systems with more functions are more expensive to purchase, operate and maintain. Primarily due to the costs of additional functions, such as monitoring, that do not directly contribute to the core function of overspeed protection. More functions require more hardware, increases the costs of the system development, manufacturing and calibration, as well as the higher installation costs (i.e. wiring, instrumentation cabinets, etc.). The more hardware functionality, the more specialized and maintenance intensive the system becomes.
Complexity and expertise
With complexity comes a more demanding requirement for extensive know-how regarding the configuration, training, operation and maintenance of the overspeed protection system. The systems are usually only checked during shutdowns, making their reliability of utmost importance. As overspeed protection systems do not require daily attention, it is generally not a dedicated expertise but part of a larger job description. As such, it is important that these systems are as straightforward as possible, and not dependent of a diminishing expertise. The more complex the system, the bigger the chance of human errors in the configuration and operation. This is especially the case with overspeed protection systems, as nobody really gets the opportunity to gain experience due to the long maintenance intervals.
Verification and testing
The more complex a safety system, the more demanding its testing and verification requirements are. To test and verify a safety system the process is interrupted; a long proof test interval negates the need to interrupt the process regularly. A system that is focused on solely the core of overspeed protection can reach test intervals of above 10 years, to a point where it does not have to be tested before reaching end-of-life. It is important to note that the more functions an overspeed protection system has, the smaller the test interval becomes, and the more the process is interrupted. It is therefore important to have a suitable system for your specific application, rather than implementing a system that is “overkill” for the application.
The solution: The SpeedSys 200, is a SIL-rated overspeed detection system for rotating machinery. It delivers the core layer of protection with a compact architecture. Its small technical footprint and low-impact installation enables advanced protection to a wide range of applications. SpeedSys 200 is available for SIL 2 applications.
SIL3 Pulse Conditioners for Frequency based signal management on Rolling Stock and critical machinery. The P16000 accepts signals from speed sensors and converts them into electrically isolated standard analog signals for transmission to other instrumentation and/ or control systems. Multiple conditioners can be used to provide signal splitting without degradation of the signal quality, reliability or common mode voltage limitations.