What Is This Voltage Transducer  - Page 1
Forum section: electronics / projects

author: bostonman
author_rank: Super Contributor
timestamp: October 02, 2022, 02:27:44 pm
content: I came across one of these:https://www.digikey.com/en/products/detail/cr-magnetics-inc/CR4510-150/2500387I've heard of 'transducers' before, but, from refreshing my mind, they are a device that converts one form to another.This piece seems to take noisy AC and converts it to DC, but I'm uncertain how exactly it's used and its benefits.

author: electr_peter
author_rank: Unknown
timestamp: October 02, 2022, 02:36:08 pm
content: Device is True RMS converter, multimeter of sorts. Input AC on one side and output linearly proportional AC RMS value in DC voltage (or 4-20mA current). Just select a model with required (expected) AC voltage and DC output needed.Useful, because it measures something (in this case TRMS AC) in the same standard output as current sensors, pressure sensors, etc.

author: bostonman
author_rank: Super Contributor
timestamp: October 02, 2022, 02:44:21 pm
content: The one I have is the -150 and I somewhat had an idea of what this device is/does before posting this message, but I still remain a bit confused.It needs 24V DC from a source and I can connect my house 120V AC to the input. It will then output a 0-5V DC voltage that will tell me what the AC is even though the sine wave is (assumed to be) noisy?I assume a more realistic use would be on maybe an AC motor that is causing noise on the AC wave form, this will convert it to something I can read on a D/A chip?If so, I don't see a graph that has input vs. output.

author: electr_peter
author_rank: Unknown
timestamp: October 02, 2022, 03:08:40 pm
content: Think of it as a multimeter - feed in AC signal on the input, it calculates TRMS value and outputs it in terms of DC voltage (rather than LCD display). It simplifies measurement, because DC is easier to measure than changing AC signal.If your equipment needs TRMS signal, it is useful. Most cases relate to various VFD motors and such, where AVG responding multimeters show inaccurate results. See discussions on AVG vs TRMS multimeters.And it is not a miracle, it will not show TRMS for any random signal, just for "normal" bandwidth limited signals like sine, square, triangle, sine with small noise.

author: bdunham7
author_rank: Super Contributor
timestamp: October 02, 2022, 03:40:04 pm
content: This is something that would be used in an industrial process control panel. The DIN rail, 24V supply and availability of models with 4-20mA outputs and 3-phase inputs indicate this.A typical use might be something like a large electrical heating element, perhaps PWM controlled, used in a process where you want the control unit to know the exact power applied to that element at any given time. You would put the unit in the panel along with all of the other DIN-rail units, connect it to the 24V supply, the control unit and across the PWM heating element and you have your input.

author: WattsThat
author_rank: Frequent Contributor
timestamp: October 02, 2022, 09:43:14 pm
content: The TL;DR:The RMS value of an AC waveform does the same amount of work to an equal value DC voltage.The device outputs a 0-10v dc level that is proportional to the RMS voltage on the AC side. Knowing the resistance of the load on the ac side and applying Ohms law, you can calculate the applied power.This is a crude simplification of bdunham7’s more technically accurate usage description.

author: TimFox
author_rank: Super Contributor
timestamp: October 02, 2022, 11:05:18 pm
content: "4-20 mA" is a common industrial specification for transducer outputs, often found on DIN-rail mount devices.Many such devices do not require an external power supply, relying on the minimum 4 mA current of the external two-wire circuit to power the transducing guts.Usually, 0 input is mapped to 4 mA output, and full-scale input is mapped to 20 mA output.If the two-wire circuit is broken, of course, the measured output current falls to 0, which indicates failure.