ION IEEE 519 program questions

[conradvr_hexeis]

I have been looking at the IEEE 510 ION code for the ION7650 and have a few questions about some of the formulas used.  I haven't looked at the ION7400 or ION9000 code yet.

Q1.  The framework requires the manual entry of Fault Current Isc and Demand Current IL.  The ION code calculates the Isc/IL ratio using these entries.  The code also calculates Isc/IL Actual using 3 parts of code.

Part 1: There are three Demand modules to calculate the Demand Phase Current. 

Part 2: These are connected to three Maximum modules to calculate the three Peak Demand Phase Currents 

Part 3: The code then calculates Isc/IL Actual = Isc / SUM of the 3 Peak Demand Currents.   

Question: Why are the Phase Current summed? Shouldn't the formula be Isc/IL Actual = Isc / Maximum of the 3 Peak Currents?

Q2.  The code sets IEEE519_I_Dmd = Manually entered Demand IL / 3.  It then uses the IEEE519_I_Dmd  as the input Max Demand to the three Current Harmonics Measurement Modules, meaning the Harmonic % values are a % of IL/3 and not a % of IL.

Question: Why are they using IL/3 and not IL as the Max Demand value input?

[Bojan]

As Isc represents 3-phase short-circuit current within a LV installation, my guess is that SUM of the 3 Peak Demand Currents represents the best approximation of maximum demand load current at PCC under normal load operating conditions, even those Peaks may not be coincidental. 

[DanL]

When you use the word "code" (in several places in your question), are you ONLY referring to user-customizable framework logic in a custom, non-shipping framework developed for the ION7650 (pre 2014), or are you instead referring to PME, software report, or other software "code"?

For what it's worth: The ION7400 and ION9000 framework logic was completely updated and refactored for IEEE519:2014

In either case, I strongly recommend using with configuration wizard as part of ION Setup for configuring ION meters (and especially in regards to IEEE519 configuration)

[conradvr_hexeis]

Hi @DanL ,

Correct, I was looking at the ION Framework using Designer, we call this the code.  Also confirming we use ION Setup to configure these modules.  The reason I am looking at the ION Modules is the V & I harmonics data in the IEEE 519 report didn't look correct.

I have powered up an ION9000 on the test bench and had a look at its ION Framework and it is programed as I expected.  The differences are summarized below: 

1. The ION7650 Actual Isc/IL is approximately 1/3x actual.

-- The Actual_IDmdMax should be maximum of the 3 Phase Demands not the SUM.

-- This value is no longer calculated in the ION9000

2. The Current TDD is about 3x actual

-- The Max Demand input to the three Harmonics Measurement Modules should be the entered IL and not IL/3

- The ION9000 uses the IL as entered

3. The Current Individual harmonics as a % of max Demand are 3x actual

-- The Max Demand input to the three Harmonics Measurement Modules should be the entered IL and not IL/3 

- The ION9000 uses the IL as entered

Can you please confirm these findings, as if they are correct the TDD, I Harmonic% and Actual Isc/IL data generated by the ION7650 is significantly incorrect.  To rectify this issue, the formulas in the Arithmetic Module (screenshot below) can be updated, leaving all the other modules as is.

[Bojan · Accepted solution]

On another note to your discussion what is better approximation for ION7650 IEEE519:2014 IL parameter - Average or Maximum of the 3 Peak Demand Currents, what should be the IEEE519:2022 IL as entered value and how to get it?
 

 

[conradvr_hexeis]

Hi @Bojan, generally IL will be calculated as the mean/average of the monthly maximum demand over the last 12 months.   Ideally you need to get access to 12 months of Demand Current data.  On sites that don't have this data we generally use the 15/30-minute interval kWh and/or kVA data from private or Utility meters.  If you can't get this data, here we use the monthly power bills as they detail monthly maximum Demand kVA and we convert this into Maximum Demand Current, add up the last 12 months and divide by 12 to use for IL.

Given the site's phase loads should be balanced, using the 3 phase average or the maximum of the 3 phases will yield a similar IL value.