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EVM430-F6779: Can this EVM be operated with Single Phase supply?

DIPEN SHAH
Intellectual 405 points

Part Number: EVM430-F6779
Other Parts Discussed in Thread: MSP430F6779, MSP430F6736

Namaste Reader,

As per my understanding, the EVM430-F6736 is the recommended EVM for Single Phase E-metering solution while the EVM430-F6779 is the recommended EVM for Three Phase E-metering solution.

In this regards, I have the below 2 queries.

1. Can the EVM430-F6779 be used for Single phase E-metering application? Would this EVM replicate the EVM430-F6736 with no input to the 2nd and 3rd phase inputs?

2. Can the EVM430-F6736 and EVM430-F6779 be used for E-metering application in India where in the 1-phase and 3-phase voltages are 230 V and 240/ 415 V respectively @ 50Hz frequency?

Thanks | Regards,

Dipen

  • 0
    TI__Mastermind 49692 points

    Hello Dipen,

    Thanks for your post and interest in our e-meter devices and EVMs.

    DIPEN SHAH said:
    1. Can the EVM430-F6779 be used for Single phase E-metering application?

    Sure, you could use the MSP430F6779(A) for single-phase applications, but it's more expensive than the MSP430F6736(A) because it has 4 more Sigma Delta ADC channels. Single-phase configurations require 2 or 3 channels, which is why the MSP430F6736(A) is recommended.

    DIPEN SHAH said:
    Would this EVM replicate the EVM430-F6736 with no input to the 2nd and 3rd phase inputs?

    The EVM430-F6779 features two on-board power supplies: a resistor capacitor (RC) power supply, switching power supply. The RC power supply requires that all three phases are connected, but the switching power supply only requires Phase 3. Refer to the schematic in the user's guide for more details.

    DIPEN SHAH said:
    2. Can the EVM430-F6736 and EVM430-F6779 be used for E-metering application in India where in the 1-phase and 3-phase voltages are 230 V and 240/ 415 V respectively @ 50Hz frequency?

    Yes, our EVMs are excellent references for these applications. For RMS voltages higher than 230V, you'll have to adjust the default voltage dividers measuring the RMS voltage to ensure that the input voltage to the SD ADC channel doesn't exceed the max Full-Scale Range (FSR). These designs support 50Hz and 60Hz but are not intended to be used as an end equipment straight out-of-the-box. They are reference designs only.

    The advantage here is that the MSP430F6736(A) and MSP430F6779(A) devices are very similar and code can be ported fairly easily between the two.

    Regards,

    James

    MSP Customer Applications

  • 0 in reply to James Evans
    Intellectual 405 points

    Namaste James,

    Thank you for your prompt reply. The reason for putting up this query on the forum is to understand if I can use the same EVM as a reference design for 1-Phase and 3-Phase designs, instead of the two separate EVM boards. 

    James Evans said:

    The EVM430-F6779 features two on-board power supplies: a resistor capacitor (RC) power supply, switching power supply. The RC power supply requires that all three phases are connected, but the switching power supply only requires Phase 3. Refer to the schematic in the user's guide for more details.

    Okay. So what I understand is that I can use only the Switching Power Supply and Phase 3 of the EVM430-F6779 on this EVM board for 1-Phase designs. Kindly confirm my understanding.

    James Evans said:

    For RMS voltages higher than 230V, you'll have to adjust the default voltage dividers measuring the RMS voltage to ensure that the input voltage to the SD ADC channel doesn't exceed the max Full-Scale Range (FSR).

    Could you kindly share the TI link or some reference material explaining the adjustment of the default voltage dividers? I might be wrong as I say this but, my simple understanding is that there must be some kindly of potentiometer for adjustment of the voltage for FSR measurements. Or is a physical change in resistor required post-calculations?

    James Evans said:

    The advantage here is that the MSP430F6736(A) and MSP430F6779(A) devices are very similar and code can be ported fairly easily between the two.

    This is definitely a big plus to speed up the development. Happy to know this.

    Thanks | Regards,

    Dipen Shah

  • 0 in reply to DIPEN SHAH
    TI__Mastermind 49692 points

    Hello,

    DIPEN SHAH said:
    Okay. So what I understand is that I can use only the Switching Power Supply and Phase 3 of the EVM430-F6779 on this EVM board for 1-Phase designs. Kindly confirm my understanding.

    Yes, that's correct.

    DIPEN SHAH said:
    Could you kindly share the TI link or some reference material explaining the adjustment of the default voltage dividers? I might be wrong as I say this but, my simple understanding is that there must be some kindly of potentiometer for adjustment of the voltage for FSR measurements. Or is a physical change in resistor required post-calculations?

    Please read Section 3.2.1 in the Implementation of a Three-Phase Electronic Watt-Hour Meter Using the MSP430F677x(A) application report. In Figure 5, the resistors R11, R12, and R13 are the upper part of the voltage divider circuit, and resistor R19 is the lower part. If you're unfamiliar with voltage divider circuits, just search for it online to learn more. Basically, the input RMS voltage gets scaled down (ratio of upper resistance over sum of upper and lower resistances) to within the FSR by these resistors. Now, the FSR values given in the datasheet are peak voltages not RMS voltages. Thus, you'll have to convert from RMS to peak by multiplying by sqrt(2). Then, you can select the proper resistances and replace them on the EVM.

    Regards,

    James

    MSP Customer Applications

  • 0 in reply to James Evans
    Intellectual 405 points

    Namaste James,

    Sincerely appreciate your timely inputs on all of my queries. Wishing you continued success!

    Thanks | Regards,

    Dipen Shah

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