Discrepancy in current readings between PowerTag and PQ Meter

[Stuart_Cheng]

Hi All,

I am experiencing a discrepancy in current readings on the VSD (ATV212HD15N4).

In standby mode, the PowerTag (A9MEM1570) reports higher current values compared to Hioki instruments.

Standby Mode Comparisons:

• PowerTag: 2–4 A
• Hioki Clamp Meter: 0.8–0.9 A
• Hioki PQ Analyzer: ~0.95 A

When switched to bypass (CB directly to contactor), the PowerTag reading drops to 0 A, indicating the abnormal readings are related to the VSD.

However, opposite results were observed in operation mode; the PowerTag shows lower current values than the Hioki meters.

Operation Mode Comparisons:

• PowerTag: 16–19 A
• Hioki Clamp Meter: 23–24 A
• Hioki PQ Analyzer: 23–24 A

Does anyone have similar experiences and know how to explain this situation? Thank you.

[Thierry_Baudard]

Hi @Stuart_Cheng

A PowerTag is designed to be installed only on a 50/60 Hz electrical network, within the voltage range specified in the product documentation.

A variable speed drive adjusts both frequency and voltage to control motor speed. As a result, it is very likely that PowerTag measurements will be inaccurate if the PowerTag is measuring currents on the output side of the drive (although I do not know whether this applies to your installation).

I would also like to emphasize that, as stated in the PowerTag instruction sheet for reference A9MEM1570 (doc QGH70), a PowerTag must never be installed downstream of a variable speed drive, as this may cause excessive overheating, potentially leading to its destruction.

[Stuart_Cheng]

Hi @Thierry_Baudard,

Thanks for your reply and apologize for not making it clear earlier. We installed PowerTag upstream of the VSD, but still encountered an issue, which is the strange part.

[Charles_Murison · Accepted solution]

Hello @Stuart_Cheng ,

If you are still having strange behavior, please reach out to your local technical support to start a case to troubleshoot.

Regards,

Charles