SIS safety meter system response speed

The basic principles of SIS are as follows (as mentioned in zhuanlan.zhihu.com):

• Independent setup principle: SIS should be independent of the process control system, and its detection elements, execution elements, logic operators, and communication parts should be set up separately. If SIS cannot be set up independently, it should be ensured that SIS acts before the process control system.
• Redundancy principle: SIS must be designed with redundancy to ensure that it can detect faults and take appropriate action.
• Fail-safe principle: SIS should be designed to fail safe, i.e., in case of failure, the system should take appropriate action to prevent hazardous events.
• Diagnostic coverage principle: SIS should have a high diagnostic coverage rate, i.e., it should be able to diagnose all faults in the system.

The SIS safety instrument system has a good response speed and its response time is generally 10~50ms

sis safety instrument system is mainly used in the alarm part of the factory control system, which can alarm or stop according to the test results of the system, is a relatively important component. It has many characteristics, a wide coverage, has a high safety, can be a good prevention of potential dangers, and has a good fault tolerance, in various industrial fields of the application is very common, the following to introduce some characteristics of sis safety instrument system.

Safety instrument system SIS mainly has the following characteristics:

(1) IEC61508 as the basic standard, in line with the international safety association provisions of the instrument safety standards.

(2) With a wide coverage, high safety, self-diagnosis function, can detect and prevent potential dangers.

(3) fault-tolerant multiple redundancy system, SIS generally adopts multiple redundancy structure to improve the hardware fault margin of the system, and a single fault will not lead to the loss of SIS safety function.

(4) The application program is easy to modify, and the software can be modified according to the actual needs.

(5) The coverage rate of self-diagnosis is large, and the number of points that need to be checked by workers during maintenance is relatively small.

(6) Fast response speed. The response time from input change to output change is generally about 10-50ms, and the response time of some small SIS is shorter.

(7) It can realize the safety design of the whole loop composed from the sensor to the actuator, with I/O short circuit, broken line and other monitoring functions.

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