STPM33 SCHEMATIC REVIEW NEEDED

[XTAL7897]

Schematic review needed, considering given standards IEC 610004-2, 610004-3, 610004-4, 610004-5, 610004-6, 610004-11, CISPR 14-1 CLASS A.

I have attached screen shot of my schematic, please go through it and check.

The screen shot contains

• STPM33 IC section,
• Reset and Digital isolator section,
• Control reset section
• CT section,

Please do review it. We are designing it for 115VAC with multiple loads on CT which vary till max 1A load.

Any changes/recommendation are welcomed.

Thank you.!!

 

[Peter BENSCH]

Welcome ​@XTAL7897, to the community!

Thank you for sharing the schematics.

The community can usually help with specific technical questions and design suggestions, but full compliance assessment against those standards is typically the responsibility of the system designer and must be validated at the system level. For your design, the final result will also depend on the PCB layout, protection concept, isolation distances, grounding, filtering, and full-system behaviour.

For detailed compliance support, you might contact the application support team of your local distributor.

The community may not take over the full compliance review, but members will likely be happy to help with individual schematic questions.

Good luck!

Regards
/Peter

[XTAL7897]

Hi Peter,

Thank you for your reply. We are using STPM33 energy metering IC. Can you please review the section of STPM33 we have some doubts in this section? We are using 2 STPM33 IC in our project. We are planning to use 1st STPM33 IC for energy and power measurement of Complete system which works on 115VAC 60Hz and second current input to sense the current consumed by pump. 

We are planning to use second STPM33 to measure currents of inductive and resistive loads.

1. For 1st STPM33: 
   VIP1 is connected to input voltage of system i.e. 115VAC, 60Hz.
   IIP1 pin is connected to secondary winding of CT1(which measures total system current present on 115VAC)
   IIP2 pin is connected to secondary winding of CT2(Which measures the Current of pump)
2. For 2nd STPM33:
   VIP1 is not used.
   IIP1 is connected to the secondary winding of CT3(which measures the current of hearter)
   IIP2 is connected to the secondary winding of CT4(which measures the current of Peri pumps and solenoid valves)
3. If we use this type of circuit is it ok?
4. Please review the reset circuit for STPM33 IC. We are using power reset circuit. Kindly find attached image. We are not getting that instead of power reset can we use EN pin of STPM33 to give reset to STPM33 whenever the IC will stuck?
5. While measuring Voltage and current using STPM33, is it required to connect analog ground of IC to VIP1 negative and IIP1 negative? If we connect analog ground to neutral (VIP1 negative) and IIP1 negative, will galvanic isolation of CT will break?
   
   Kindly find attachment. 

Thank you for your valuable support!

[Peter BENSCH]

Your request for a review is not a request for help with a technical problem, but rather a classic request for an investigation into the device you developed. For such cases, there are companies that offer this kind of support, although it will not be free of charge.

Otherwise, as already suggested, you can contact an authorised distributor of your choice, who will be happy to help you further if the business case is sufficiently interesting.

Hope that helps?

Regards
/Peter