ION9000 measurement accuracy and time synchronization

[Stuart_Cheng]

Hi All, I have two inquiries about ION9000

1. Would the measurement accuracy be lower when ION9000 is doing half-cycle true RMS readings? Or the accuracy is as good as the datasheet states?

2. If there are several ION9000 in the network and we use PTP to do the time synchronization, would all the meters sample and update the measurement at the same time?

Thank you.

[DanL · Accepted solution]

1. The ION9000 Power Quality Aggregator (PQA) Module complies to IEC61000-4-30 Class A.

https://www.productinfo.schneider-electric.com/ion9000/viewer?docidentity=PowerQualityAggregatorModu...

The PQA module has six half-cycle voltage RMS outputs that meet the required "+/-0.1% of Udin" (in the range of 10% to 150% of Udin) accuracy spec required for Class A.

https://download.schneider-electric.com/files?p_enDocType=User+guide&p_File_Name=7EN72%E2%80%930185%...

The high-speed powermeter module outputs do not perform the same prescribed measurement alignment algorithm specified and required by the 4-30 standard.

2. Mostly yes. ION9000 meters correctly configured for PTP (Clock source = COMM, etc) will produce synchonized and time-aligned IEC61000-4-30 Class A readings (also all 1-second measurements will be aligned). The alignment time accuracy for Class A is +/- 1cycle.

https://www.productinfo.schneider-electric.com/ion9000/viewer?docidentity=ClockModule-3E8613C1&lang=...

[Stuart_Cheng]

Hi @DanL,

Many thanks for your information. Would like to check if my understanding is correct.

1. When ION9000 is doing half-cycle true RMS reading, we only can say the accuracy of the “voltage” measurement meets the accuracy spec required for IEC 61000-4-30 Class A (+/-0.1%). But other parameters such as frequency and power, we cannot make the same statement (accuracy probably would be lower than the value listed on the datasheet?)
2. It’s clear that if we set up the PTP time synchronization correctly, the alignment time accuracy would be +/- 1cycle when the meters are doing a 1-second measurement. How about when all the meters are doing half-cycle true RMS reading? Would all the meters sample and update the measurement at the same time and what would be the uncertainty?

Thank you.

[DanL]

1. All six of the provided 4-30 Class A One-Cycle-Every-Half-Cycle true RMS, phase-aligned voltage measurements (Urms[½]) provided by the PQA module are designed and tested to meet the required accuracy for IEC 61000-4-30 Class A (+/-0.1% of Udin).
   The other One-Cycle-Every-Half-Cycle parameters originating from other ION modules (such as frequency and power from the HS Power Meter Module) are not designed to nor specified by 4-30 and thus have no official reference. However, because all these parameters are used by the calculations for longer intervals (1Second, 150/180Cycle, and 10minute), we do know that (under steady state) these values are typically just as accurate.
2. The six high-speed phase-aligned voltage measurements (Urms[½]) from the PQA module are specifically designed to be repeatable between time synchronized devices. The other HS values will not provide phase-aligned measurement windows, but will still be synchronized to within +/-1cycle (while using PTP). 

[Stuart_Cheng]

Hi @DanL 

It is much clear now. Many thanks for your help.

best regards