1/24/2019 11:58 AM | |
Joined: 4/28/2015 Last visit: 10/3/2024 Posts: 3 Rating: (0) |
Good morning, I was doing a new configuration with Safety Evaluation Tool and when I was going to set a CCF value, I found two additional fields called: - MTTFd of Testing Channel - Safe state via Testing Channel I noted that these two fields appear when you use at least a category 2 architecture and the fields only appear in the reaction field of the safety function you are configuring. You can find attached the configuration in SET and you will find these two new fields in the red remarked rectangles. The question is: What do these fields mean? Could you explain how do they affect to the safety level?. Are these values related to the feedback circuit of the contactors and only to the reaction devices? Regarding the two options for the MTTFd of the testing channel: <50% of the functional channel/ >50% of the functional channel what is the explanation to choose one of these two options?. I read a previous thread about this issue in the forum but the explanation given is not clear to me. Could you help me?. Thanks in advance for your help and best regards Ruben Portillo Zamora AttachmentSafety Evaluation Tool_new fields.pdf (1140 Downloads) |
1/25/2019 12:10 PM | |
Joined: 4/28/2015 Last visit: 10/3/2024 Posts: 3 Rating: (0) |
Thanks for your help and your info. I´ve been reading some information about this issue and I have doubts about how define a Test equipment. I mean, for example, working with one or two contactors (in series), what the standars define as test equipment could be the feedback circuit of the contactors?. The information I read also point at the possibility of a test equipment as an external device (there is a Siemens FAQ where a circuit breaker is used as Test equipment, you can find this document attached). In the case of the feedback circuits of the contactors can be used as test equipment, should I calculate the MTTFd,te value for the NC contacts os the feedback circuit?. I´m not sure about this point If so, should be this MTTFd, te value higher than half of the MTTFd L. Is this MTTFd L related with the logic block (Safety relay or Safety PLC)?. Thanks in advance for your help and best regards Ruben Portillo Zamora AttachmentFAQ_40349715_circuit_breaker_V31_en_2018-06.pdf (1195 Downloads) |
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