TIDA-00637: CT Part Number Used in TIDA-00637

TI-CSC

Part Number: TIDA-00637

Hello E2E Experts,

Good day.

I have reviewed the documentation thoroughly, and I just wanted to confirm that in the document titled "Implementation of a Single-Phase Electronic Watt-Hour Meter Using MSP430F6736(A) (Rev. F)" (slaa517f.pdf), there is no mention of the accuracy class of the current transformer that is needed to achieve the Class 0.2 E-Meter rating. However, in "Level 1 and Level 2 Electric Vehicle Service Equipment (EVSE) Reference Design" (tidub87.pdf), which is the document that led me to slaa517.pdf, on page 18, it mentions that "An external 0.05% CT is required to meet the high accuracy specification with the appropriate burden resistor tuning." I just want to confirm that 0.05% is the intended number and not 0.5%. I ask because I have had significant difficulty finding a 2000:1 turn ratio current transformer with a 0.05% accuracy. If possible, can the part number of the current transformer used in the EVM for the single-phase meter be provided as a reference?

Thank you in advance.

Regards,

CSC

over 2 years ago

0 Errol Leon6 over 2 years ago

TI__Expert 5850 points

Hello CSC,

I will look into accuracy number of the CT and get back to you soon.

Best regards,

Errol

0 TI-CSC over 2 years ago in reply to Errol Leon6

TI__Genius 11685 points

Hello Errol,

Good day.

Do we have the accuracy so far? I look forward to your response.

Regards,

CSC

0 Errol Leon6 over 2 years ago in reply to TI-CSC

TI__Expert 5850 points

Hi CSC,

Thank you for your patience, I was able to find the site where we acquired the CTs for the TIDA-010036 and TIDA-010037. TIDA-010037 is a Split-phase metrology reference design for electricity meters that meets ANSI C12.20 Class 0.1 active energy accuracy requirements across 10000:1 input range.

Which is achieved with ADS131M04 and MSP432 metrology library software calibration you can achieve accuracy. Attached below is the link to the CTs:

http://www.shenk.com.cn/proData.aspx?cateid=153&id=353

Best regards,

Errol

0 TI-CSC over 2 years ago in reply to Errol Leon6

TI__Genius 11685 points

Hello Errol,

Good day.

Is it possible to use a different vendor? Are there alternatives? Is the accuracy 0.05% or 0.5%?

Also, I am using the MSP430F6736, so I am curious how applicable is the suggestion of an MSP432 solution.

Regards,

CSC

0 Errol Leon6 over 2 years ago in reply to TI-CSC

TI__Expert 5850 points

Hi CSC,

It is possible to use a different vendor. One alternative you could look at is Vacuumschmelze.

https://vacuumschmelze.com/products/Inductive-Components-and-Cores/Current-Transformers

The accuracy is 0.05% based on your initial inquiry. The MSP432 solution like TIDA-010036/37 are applicable and we have metrology software to implement the calculations.

ADC-ENERGY-METROLOGY-LIB-SW

This could be implemented on the new MSPM0 device family which can be a cost effective replacement MCU for MSP432 which implements the metrology calculations.

Best regards,

Errol

0 TI-CSC over 2 years ago in reply to Errol Leon6

TI__Genius 11685 points

Hello Errol,

Good day.

I would like to highlight my inquiry below:

"Also, I am using the MSP430F6736, so I am curious how applicable is the suggestion of an MSP432 solution."

Regards,

CSC

0 TI-CSC over 2 years ago in reply to TI-CSC

TI__Genius 11685 points

Hello Errol,

The customer is using MSP430F6736AIPZ. However, you mentioned the use of MSP432 or MSPM0 devices.

Here is the question:

Can I use MSP430F6736AIPZ in replacement to MSP432 or MSPM0?

Let me know how.

Regards,

CSC

0 Errol Leon6 over 2 years ago in reply to TI-CSC

TI__Expert 5850 points

Hi CSC,

I have looked at MSP430F6736 and this is an e-meter SoC. This can be replaced with a 2 chip solution using our ADS131M0x and MSPM0. That would be a cost effective solution in place of the MSP430F6736. One example of the 2 chip solution is TIDA-010037 which I have linked below.

https://www.ti.com/tool/TIDA-010237

Depending on the features needed we have a metrology library for basic metrology features working on the MSPM0 and the following library below that has worked on the MSP432.

https://www.ti.com/tool/ADC-ENERGY-METROLOGY-LIB-SW

Best regards,

Errol

0 TI-CSC over 2 years ago in reply to Errol Leon6

TI__Genius 11685 points

Hello Errol,

Good day, and thank you for the additional information.

I have reviewed that BOM extensively, so if you can so kindly identify which line is the Current Transformer in the associated BOM (with the URL www.ti.com/.../tidrjj1) I would greatly appreciate it.

The design guide (www.ti.com/.../tidub87) points to the Single-phase Meter EVM (www.ti.com/.../TIDM-SINGLEPHASEMETER). Which also does not list a CT in its BOM (www.ti.com/.../tidr105). So the question returns, what is the CT that is part of either reference design, and which is used with the TIDM-SINGLEPHASEMETER physical hardware? It does appear to be from ShenK Electronics (http://www.shenk.com.cn/), but the link which was shared before DOES NOT have a 5(100) A/2.5mA 10Ohm current transformer, and the part itself DOES NOT have any part numbering or identifying markings for the specific part.

So I guess my question is now, can you recommend an alternative CT that can be dropped into either one of the two above-mentioned TI designs?

0 Errol Leon6 over 2 years ago in reply to TI-CSC

TI__Expert 5850 points

Hi CSC,

It took a while to find some with the accuracy requirements but have the following sensors:

High Accuracy Solid-Core Current Transformer - AcuCT S77 | Accuenergy

Hemeict - High Precision 0.05 Class Accuracy

top is 0.15% and bottom is 0.05%

Hope this help!

Best regards,

Errol

0 TI-CSC over 2 years ago in reply to Errol Leon6

TI__Genius 11685 points

Thank you Errol for your support.

I will now lock the thread.

Regards,

CSC

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TIDA-00637: CT Part Number Used in TIDA-00637