The measurement of pressure had once been a monopoly of Bourdon tube pressure gauges, and if you wanted to check the pressure at any location in a fluid power circuit, you had to go right to the source to install a pressure gauge at the location you wished to measure. The invention of test points and micro-bore hoses allowed for some distance between point of measure and point of reading, but reliable and accurate readings were still limited.
The proliferation of electronics into fluid power has changed the way we can measure pressure, and has enabled versatility not enjoyed previously. Pressure transducers are solid state, meaning there are no mechanical moving parts, instead using something called a strain gauge which changes in resistance when warped out of shape by pressure. Their solid-state nature means they are very reliable, often lasting millions of cycles.
Pressure transducers require a power source to give their output signal, usually a 24-V input. Their outputs are typically one of the standard control signals, such as 0-10 V or 4-20 mA et al. This signal can be fed into a PLC for feedback of closed loop control, such as servo-pump pressure control, or the transducer signal can simply plug into a digital display.
Transducers are typically male-threaded and plumbed into any location where you wish to measure pressure. When used in conjunction with a PLC, the basic plug-in type with a M12 or DIN connector is all that is needed. The transducer must be chosen for the appropriate pressure range it will measure, especially if you wish it to be accurate. For example, if you are measuring around 100 psi with a 0-10 V transducer, using a 1000-psi transducer will only ever read 1 V, leaving the rest of the pressure range unused.
Pressure transducers are also available with on-board electronics, including displays and switches. One device, for example, can display the pressure, provide a handful of switch’s outputs with configurable switch-back points, and also provide its analog output for a PLC to use as well. With the cost of electronics at an all-time low, they’re not as expensive as you would think, either.
I fully agree with the article, not only pressure but temperature transducers as well are becoming more of the norm in critical applications. Please also keep in mind that the transducers are available in many electrical terminations such as DIN, cable, M12, Integral Deustch as well as different sensing elements such as ceramic and thin film. PVS Sensors in South Carolina offers many versions of the transducers.
Hi Reader,
Would like to add bit More to the article with short 5 years of experience in this industry. The input supply voltage can be between 8 – 32v based up on the application and product offering. Also, there are sensors available which takes 5 v as in out and give 10% to 90% of the supply as output based up on pressure.
There are many companies which as providing similar solution for various segments like Hydraulics, Penumatics, Water applications and others
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Thanks and have a great day ahead!