On the Visaya blog, we share the most popular discussions across social media about the Process Automation Industry. These thematic conversations center around queries, discussions, and ideas that people are keen to contribute to. Today´s insight analyzes the causes of a voltage drop according to professionals across the Instrumentation industry.

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In one scenario, the voltage of a circuit drops and the voltage and wire, also resistant to AC or DC, gradually reduces. Interpreting various causes for such a scenario, Opili Benjamin, the Instrument Commissioning for Hyundai Heavy Industries (Nigeria), believes that if the situation was manageable at the time of installation, this suggests that wire sizing might have been fine to work with. However, a loose termination over time could have caused such a troublesome scenario.

image for Voltage Drop in an Electronic Circuit
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Wayne Wilson, Owner of Wilson’s Industrial Instrumentation Installation Inc. (Louisiana), adds, “As for a change in the load, if one has added some things to the section that someone was using and everything was in control, the power supply needs to be checked without any load applied. Then, you can add devices, while checking that the voltage could have a faulty field device drawing it down.”

Hannes Dreyer, Owner of Natprotech Instrumentation (South Africa), shares his views on the reasons for a voltage drop. He realizes that an ambient temperature and heat caused by various components installed in panels can cause transmitters to fail or become unstable. “This is especially applicable when working with mA and mV transmitters. As such, it’s always important to keep the control panel free from dust and moisture. Moreover, never overheat and overload power supply; stick to the rating,” he explains.

When we hear about a voltage drop, the first thing we think of is the use of faulty components. According to Manjunath Maganahalli, Consultant-Power Consult (Saudi Arabia),  adds that a voltage drop in an electric circuit is caused by faulty components, due to a power supply possibly being grounded at someplace in the circuit, a selection of conductor(wire), whether it is PCB (printed circuit board), track size, or a loose connection in the circuit or an improper soldering.  

image for Voltage Drop in an Electronic Circuit
Courtesy of Total-tech

Hareesh GS, Instrumentation Engineering, CPCRI (India), adds, “This can happen because of faulty active/passive components. If you’re sure that the power supply is perfect, you should concentrate on the circuit/network. Then, find the culprit by isolating them from the +V rail and ground plane, one by one.”

Stressing the fact that overheating is a primary concern for such a situation, Keith Puttick, an Instrument Technician in Newcastle upon Tyne, United Kingdom, emphasizes that a circuit is driven by components that in time overheat and become inefficient, causing a volt drop higher than expected. However, a number of factors require the replacement of the circuit board. “This is an ambiguous question, which is open to debate and depends purely on the circuit board concerned,” he believes.

Parameters and conditions, too, play a major role in this case. According to Srinivas T, Manufacturing Equipment Engineer at FLIR Systems in North Carolina, “The main problem is the length of wires from the device (a transmitter) or voltage source. However, don’t rule out loose, bad connections and grounding problems. It depends on what parameter you’re measuring. If it is a level sensor/transmitter, any field/in system transmitter will be good. This is as long as a 4 to 20MA /frequency transmitter/Fieldbus device is used instead of dc voltage such as 0-10vdc or 1 to 5vdc signals.”

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