Timeline for Lead resistance of 3 wire RTD100
Current License: CC BY-SA 4.0
19 events
| when toggle format | what | by | license | comment | |
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| Sep 17, 2020 at 11:33 | comment | added | user16324 | Compensate by increasing the excitation voltage by about RW3/R1, i.e. not very much. | |
| Sep 17, 2020 at 11:31 | comment | added | Andy aka | @powermachines the conventional way is to add a fourth wire from the red circled point marked "C" and measure that voltage and use it to compensate for the line attenuation. It's called ratiometric compensation (or words to that effect). | |
| Sep 17, 2020 at 10:55 | comment | added | power machines | @Andyaka is there any thing i can do to minimize the effects of RW3 on gain | |
| Sep 17, 2020 at 10:44 | vote | accept | power machines | ||
| Sep 17, 2020 at 10:44 | comment | added | power machines | @Andyaka i realized my mistake in interpretation of circuit ,thanks for help | |
| Sep 17, 2020 at 10:30 | comment | added | power machines | Okay i will think about it, sorry for confusion | |
| Sep 17, 2020 at 10:29 | comment | added | Andy aka | Circuit 2 is the same as your original circuit. Just think about it and then remove it because it's clearly adding confusion to all parties because it uses different reference names for the bridge components. | |
| Sep 17, 2020 at 10:22 | comment | added | power machines | in my question in circuit 2 how does it cancels the lead resistance i am not able to understand that as the output Voltage is taken from point A and B both the wire resistance is in series with RTD then how lead resistance is getting cancelled?@ BrianDrummond | |
| Sep 17, 2020 at 10:14 | comment | added | user16324 | Note the bottom of the bridge is the junction of RW3 and R4 in Andy's circuit. Now R3 is really R3+RW2, and R4 is really R4 + RW1. So RW1 cancels RW2. Your new circuit is the same apart from references : R2+RW2 balance RTD + RW1. | |
| Sep 17, 2020 at 10:10 | comment | added | power machines | @BrianDrummond in circuit 2 how the lead resistance is getting cancelled as both the wire resistance is in series with RTD unlike in the case of Circuit 1 where R3 is in series with RW2 and equally, R4 is in series with RW1 | |
| Sep 17, 2020 at 10:05 | comment | added | power machines | @Andy aka added a new circuit in that wire resistance is only added with RTD as the output voltage is taken from Point A and B, then how the lead resistance is getting cancelled? | |
| Sep 17, 2020 at 10:04 | comment | added | user16324 | No. With a 2 wire RTD both gain AND balance will be affected. | |
| Sep 17, 2020 at 9:35 | comment | added | power machines | i have read about 3 wire rtd that it is used to cancel the lead resistance like if the third wire only affects the gain of circuit so is it better if i use a 2 wire RTD as the gain will not be affected?@Andy aka | |
| Sep 17, 2020 at 9:28 | history | edited | Andy aka | CC BY-SA 4.0 |
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| Sep 17, 2020 at 9:27 | comment | added | Andy aka | I've added some more information. | |
| Sep 17, 2020 at 9:23 | history | edited | Andy aka | CC BY-SA 4.0 |
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| Sep 17, 2020 at 9:21 | comment | added | power machines | but how lead resistance is cancelled ?@Andy aka | |
| Sep 17, 2020 at 9:09 | history | edited | Andy aka | CC BY-SA 4.0 |
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| Sep 17, 2020 at 9:02 | history | answered | Andy aka | CC BY-SA 4.0 |