To what condition should dual-platinum resistance thermometers be kept in reserve?
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Many platinum resistance thermometers (PT100) used in key locations on-site are of the dual-element type, featuring two sets of outputs: one for operation and another as a backup. To what extent is this backup function utilized, and are the connection wires pre-connected as well? Connected to the controller? Switch directly to another set if one is broken? It’s only when one set used for work gets damaged that the backup set requires a connection cable. Are there any standard regulations regarding this? I would appreciate it if experienced experts could provide an answer; thanks in advance
1. Two measurement points can be taken at the same location. 2. One spare unit for easy maintenance. 3. Two units can be compared to determine whether the temperature measurement is correct. Dual thermoresistors can also be used for redundancy or backup purposes: one of the two signals from the thermoresistors is sent to the DCS for display or control, while the other signal is sent to the SIS for interlock functions.
One of these goes to DCS, while the other doesn’t go to SIS; there is no interconnection – it’s just for backup purposes, so no connection cables are needed
Conduct LOPA analysis and define SIS levels; the approaches vary depending on the level
This doesn’t meet the specifications, right? The requirement is to use two measurement points, not two branches