Three phase Voltage measurement using zmpt101b

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1

Hey so I am building a three phase voltage measurement circuit . I could measure three phase voltage using ZMPT101B module. Now I do know that zmpt101b is for single phase and max voltage of 250V on the module . Here we have 220V between L1 and Neutral and 420V between L1 and L2. So I would be connecting Phase on module to L1 and Ground on module to Neutral.

Also I noticed in the datasheet ZMPT101B Datasheet that i can just change the input voltage resistor R1 and sampling resistor R2 on the module I can measure 420V.

While i still have to run the calculations these were initial thoughts

So just wanted to check if my reasoning is proper.

2

In a three phase connection, there is an L3.

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3

Ya here it is 220V between phase to phase and 420 between phase to neutral so will the zmpt101b suit this particular application.

4

The transformer is good for 1000V, so there are other reasons why the module is limited to 250V. Simply changing resistors might be dangerous.

5

Here we have 420V between L1 and Neutral and 220-240V between L1 and L2

That makes no sense.

In a symmetrical three-phase four-wire wye system, the three phase conductors have the same voltage to the system neutral. The voltage between line conductors is V LL = sqrt(3) V LN

The sensor can safely measure the voltages between neutral and any of the lines is a standard three phase system.

Please post a link to an official document describing the system you are talking about.

6

You have got that the wrong way round.

https://en.wikipedia.org/wiki/Three-phase_electric_power

In a symmetrical three-phase four-wire wye system, the three phase conductors have the same voltage to the system neutral. The voltage between line conductors is √3 times the phase conductor to neutral voltage:
{isplaystyle V_{ext{LL}}={qrt {3}}V_{ext{LN}}.}

7

My mistake when posting sorry about that have edited it

8

Three phase what? Three phase Delta or Three Phase WYE? What do you have? Do you want to measure 3 phase voltage line to line or line to a neutral?

Ron

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Three phase line to neutral

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When you edit out mistakes in the original post , it makes subsequent posts mentioning your mistake look wrong.

It spoils the whole flow of the topic.

I'm glad I quoted you in my earlier post.

11

So a 3 phase why. So if you want to know the voltage I would use 3 ZMPT 101B transformers all Line to Neutral.

Should this be a commercial application I would go with a commercial voltage transducer like this or similar. When measuring AC voltages you have a choice. Average Responding RMS Indicating which I linked to or True RMS Responding RMS Indicating like this. The ZMPT flavors give you an average response when you write your code. Assuming a perfect sine wave a ZMPT is fine.

Ron

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