TE+on-site temperature variation+ordinary cable vs. TE+compensated wire+track-type temperature variation
Thread Content
This post was last edited by budaoweng123 on 2017-3-25 at 15:06. For thermocouple measurement circuits, there are generally two configuration options in practical projects: 1. Temperature sensing element + on-site temperature sensor + ordinary cable; 2. Temperature sensing element + compensation wire + temperature sensor mounted on tracks. May I ask, which of these two configurations has a lower cost, and by how much does the cost difference? Also, if intrinsically safe explosion protection is required on-site, then an AI safety barrier needs to be added in Option 1; in that case, wouldn’t this option lose its cost advantage? The on-site temperature variation is calculated according to Rosemount models without on-site LCD displays, while the temperature variation of the guide rails is calculated using MTL standards.
Option 2 is the main choice in most cases! Instruments that integrate temperature measurement on-site must be expensive! Plan 1 doesn’t have any advantages over Plan 2 either!
Intrinsic safety integrated temperature sensors are also expensive, right?
Using on-site temperature transmitters results in a high failure rate due to the effects of the surrounding environment, especially in heating furnaces; many of such transmitters here have failed. As for the cost, compensation wires are not inexpensive either, and no comparisons have been made. It is recommended to use Solution 2
Can the temperature-sensitive safety barrier be placed directly inside the explosion-proof box on site? The one we have here is also a domestically produced temperature-sensitive safety barrier.
It seems that Solution 2 is generally used; Solution 1 is only employed when it’s necessary to monitor the temperature on-site
This post was last edited by a new member from Anshan on 2017-3-27 at 13:37. Nowadays, control systems almost all come equipped with dedicated cards for thermal resistors RTD, thermocouples, and mV sensors. The heating setting inside the cabinet is confusing – why is it set to 4-20mA? Is it done for convenience and better visualization?
I previously posted a thread discussing this issue: http://bbs.hcbbs.com/thread-1597924-1-1.html
It is recommended to use Option 1; you can buy a Rosemount temperature sensor for around 3 thousand. High reliability
Under normal circumstances, Option 1 is chosen. However, in situations where intrinsically safe explosion-proof requirements apply, Option 2 is not either the best choice, as making that wiring box explosion-proof is extremely expensive – the cost is at least 5k!