ION9000T HSTC Settings warning in ION Setup when using PTs

[Nicholas_Brown]

I am under the impression that when setting up the HSTC Magnitude Threshold settings in the ION9000T that we are to only consider the voltage at the meter terminals.  I have an engineer setting up an ION9000T on an MV substation with 2440:120V PTs.  The nominal voltage at the meter is set at 2440V.

When configuring the HSTC settings, assuming that our only consideration is for the 120V that will actually be at the Meter terminals, we were going to leave the Magnitude Threshold at 1000V RMS as configured.  However, ION Setup gives us the following warning:

"Magnitude Threshold is below the programmed voltage nominal of 2440V and may result in excessive logging...."

Any input on if this warning should just be ignored in this instance given that we are using PTs?  Does ION Setup just not consider this situation?  Or, is my understanding of the HSTC Magnitude settings as it relates to PTs incorrect?

Thanks for any help.

[Mehran_Mehrnia]

Hi @Nicholas_Brown 

Power Meter Module which is named as Regular Power Meter module uses scaling factors
to obtain high-accuracy measurements of primary transformer levels.

So, given meter senses PT secondary voltage as 120V, the primary voltage as actual level of field voltage is taken into account based on the configured PT ratio. Therefore, an incorrect nominal value or threshold level, such as 1000V while Primary is 2440V, will cause the meter to enter an incident state, results in excessive logging.

Best Regards,

-Mehran

L3 Expert Advanced metering

[Robert_Lee · Accepted solution]

I think this is an oversight on ION Setup part as it was not expected to use HSTC with PTs as this may interfere with expected transient detection.  In most cases, the ION9000 would be *directly connected* to the voltages so ratio would be 1:1.

I've made changes to the next version to only compare to the *secondary nominal* which is computed as:

Snominal = (Vnomimal * PTSecondary) / PTPrimary

When the PT Primary secondary are 1:1 (ex. 120:120), Snominal will be equal to Vnominal but in cases where the user wants to use PTs, then it will be usually a lot lower (and will be reported as computed secondary nominal).

In your case if say you tried entering 100 for the RMS field it would show the warning as "computed secondary nominal of 120V".

For now, you can likely ignore the warning.

[Nicholas_Brown]

Thank you very much.