What are some tips for selecting and installing instrumentation cables and connectors?

All of this is true, and accurate, and is an excellent model to follow when designing, specifying, and purchasing the optimum cable for any application. However, at my last job, a highly experienced electrical engineer with a "P. Eng" by his name and on the electrical drawing used to wire up a panel said, "Awe don't worry about it: just wire it point to point and it will be OK." I brought a dozen poor workmanship issues to his attention. He did not care or even understand. We started up and had very noisy signals on our analog signals. We made it work despite a very DAM poor wiring job. We had to troubleshoot countless issues because of poor wiring and terminations. Lesson Learned: Use loop diagrams and wire correctly the first time.

Knowing the specification or function of the devices is the first step to select the correct cable/conector. Sometimes, experience can help, due to, frequently analog instruments used shielded twisted pairs, discrete device used twisted pairs, Fire and Gas detectors used triads, vibration sensors used coaxial cable, etc., however this information always have to be verified with the manufacturers. Generally all the catalogues and manuals include the technical specifications of the signal and power cables, such as type and size, as well as a typical wiring diagram.

For selecting and installing instrumentation cables and connectors ,first application and signal type to be identified ( analogue, Digital, Fieldbus, Power,..) then cable specification such as insulation, impedance lead sheath, cable amor to be checked .project engineering cable specification and instrument Cable engineering standards such as IEEE and IEC would be helpful as reference for cable selection. Suitable cable routing ,bending radius , screening, environmental protections ,loop check ,grounding and shielding are important for cable installation .

Screening the cable is very important, many often confuse this with the earth connection. Should be carried through the installation and left floating in the end device.

Always test out all of the I/O from the device or final element back into the control system. Ensure Hart or any smart addressing is correct. Document the testing results and functions check. All loop readings, feedbacks and fail safes are recorded and that it has been verified. Document, Record and fix any and all discrepancies to ensure reliability and accuracy. Follow up in the project completion process. Visual checks also ensure that the correct materials of construction are used.

I agree, but you also need to perform what’s referred to as a point to point. Make sure the correct instrument is routed through all junction boxes, RTUs, PLCs, I/O cards and shows up on the SCADA screen or DCS as the same device. Common mistakes are the A machine instrumentation controlling the B machine, numbers similar in format aren’t recognized xx-11010 and x-10110 are mislabeled. After you the point to point is confirmed, you do a Site Acceptance Test (SAT) and test the Control Logic to ensure it performs the control function intended. With a successful point to point and SAT you don’t have to do one again unless you change something that would affect it, you capture this under a Management of Change to record the change.

Minimum and maximum lengths usually called out by the device manufacturer's themselves should always be followed as well as limiting the number of intermediate connections from point to point which adds resistance or properly, impedance; which will usually be included in device manufacturer's specification for the equipment cabling or wiring installations. System designers typically will know this, but requirements of at the jobsite often get over-ruled by a contractor or sub-contractor or site project director meeting deadlines.

When I am doing CCTV installs I try to use Siamese cable and compression connectors or I prefer POE these days and cat 6. In some cases with straight RG6 I use crimpers with heat shrink.

Quando se desenvolve um sistema de teste e aquisi??o de dados, muitas empresas esquecem de mensurar n?o somente a quest?o técnica dos cabos que ir?o instrumentar o dispositivo sob teste, mas também esquecem de mensurar o valor que esse cabo pode acarretar o sistema completo. Dependendo do tipo do sistema e do lugar que a medi??o será feita, vale analisar se vale a pena trazer o equipamento de teste para mais perto do sistema que será testado e medido, se o sistema for robusto suficiente para ficar perto do DUT (Device under test), você pode reduzir (e muito) o comprimento dos cabos, diminuindo n?o só os valores, mas também outras quest?es como ruídos.