Clear, simple and straightforward basic explanation of the main aspects and concepts of intrinsic safety. Congratulations! Just a small conceptual comment: Both "classified" and "unclassified" areas need to be considered and deemed as "SAFE". Electrical, automation and instrumentation installations, in both cases, need to use equipment with appropriate "Ex" protection types (in classified areas) or associated equipment (in non-classified areas), in addition to performing the applicable installation, inspection and maintenance "Ex" service procedures, according to IEC 60079-14 and IEC 60079-17. 👍 Thus, it is suggested to use the term "UNCLASSIFIED AREA" or "NON HAZARDOUS AREA" instead of "SAFE AREA".
I can’t remember where I read it but it said that Div.2 is presence of a hazardous atmosphere less that 6 hours per year which means emergencies only and Div.1 is over 6 hours per year.
Hello, the video was really helpful in understanding intrinsic safety in a context of plc control system. But, I have something to clarify. It was said in the video that Div 1 is for environment where combustible dust is present during abnormal conditions. I think abnormal is for Div 2. Would like if you can give clarification on this. Thank you
You mentioned at the start, that the video would show how to DESIGN a circuit which is intrinsically safe? Is this video demonstrating the LOOP concept (follow the manufacturer certification exactly) and ignores the ENTITY circuit calculations? What about the requirements for the circuit calculation, the entity parameters, cable capacitance and inductance? The number of times I’ve had near misses from sub contractors, mistakenly thinking, that when they pick a barrier which will power a device in the field also means it’s safe for the hazardous area is beyond frustrating (at times has lead to follow up action with their employer when competency is an issue). Also, would it not have been easier just to say the barrier must be installed in a safe area rather than give a specific example of a purged panel which achieves this?
@fitz83 Our short videos 9n RU-vid are meant to introduce viewers to concepts used in the automation industry. Entity circuit calculations are quite a bit more involved than what our short videos can cover. And yes, in hindsight, placing the panel in a GP area would have simplified the discussion.
Hello, I am aware of IS CALCULATION concept. But for one loop only. Like BARRIER to JB to LT. But I am not sure how would be the process for IS like this case. BARRIER to JB to FIT to FE? How is The cable from FIT for FE considered in calculation?
Thank you for your question! You’ve raised an interesting point. Here are two links that I hope will help clarify the calculations for the cable from JB to FIT or FE devices. www.extech.co.za/wp-content/uploads/How-to-calculate-an-IS-loop-approval-Extech.pdf www.icetoolkit.com/IntrinsicSafetyCalculator If you need further assistance or have any other questions, please don't hesitate to reach out.
The power (usually 12VDC or 24VDC) comes from the PLC card it is attached to, or in some cases, an external power supply. Photo eyes do need a power source.
I think the power will not come from PLC card, the power is from external source, then the feedback (alarm reading or normal reading from the photo eye) ia connected to the barrier, the barrier then converts that small signal to a higher voltage signal to reach to the PLC AI card (i think the signal is Analog), if there is an alarm signal the ESD system will shutdown the power or act to prevent any explosion etc.. i think its done that why but i am not sure.
Hello GameLover! Thank you for your question! Unfortunately, I can’t fully assist as it is not in the contents of our video, as we discuss in Intrinsic safe example 1. But it is a valid question. To help you with your question, here is a head start. Here are 2 links to manufacturers that might be able to help you with these devices you are asking about. 0-10v, 4-20ma intrinsic safety barrier Zener barrier explosion-proof safety www.alibaba.com/product-detail/0-10v-4-20ma-intrinsic-safety_62468731323.html www.pepperl-fuchs.com/usa/en/classid_14.htm Signal Converters - Intrinsic Safety Barriers Happy learning from RealPars!
The short answer to your question is YES. Every part of the "circuit" must be analyzed to insure that the maximum radiated energy does not exceed the threshold for IS installations. A good summary can be found at: www.controlglobal.com/articles/2019/how-to-ensure-intrinsic-safety-for-wireless-systems/. Most wireless installations do not exceed the 2W limitation for the most stringent Group IIC environments, and when installed properly (in Ex d enclosures, for example), can be used in hazardous areas without modification.
The ET200iSP I/O cards have IS barriers built into the I/O card. It is a matter of convenience and cost to use the ET200iSP system versus a standard PLC I/O card with external IS barriers. Remember, that all systems placed into or interfacing with Zone 1, Zone 21, or Class 1 Div 2 or Class 2 Div 2 areas, must be designed for the appropriate level of protection from the field instrument through to the PLC or DCS. Just installing ah IS barrier or ET200iSP system is not alone sufficient to ensure safe operation.
A simplified answer is that Ex-ia sensors are classified as Category 1G/1D equipment, for installation in Zone 0, 1, or 2 and 20, 21, and 22 areas. Ex-d sensors are classified as Category 2G equipment, for installation in Zone 1 or 2 and 21 or 22 areas. Ex-ia sensors (such as a tuning fork level switch) can be installed in a tank with hazardous material , whereas an Ex-d sensor cannot be installed in that location.
Hi Jeremy, Thanks for your comment! We currently only provide our course videos in English, you are always able to turn on the English subtitles as that might make it a bit easier for you.
Intrinsically safe cables are designed to be UV and weather-resistant and conform to certain ISI standards. Cables that are installed in IS service should have blue jacketing/insulating covering to distinguish the cables from those installed in non-IS circuits. In many cases, the type of connection made in the hazardous area is restricted to eliminate the possibility of arcing (as with quick-disconnect cables).
If an instrument is not ATEX certified, then there is no guarantee that the construction of the instrument and its circuitry will provide the level of protection against flammable hazards that may be required.
