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Can the ION Meter calculate Total demand distortion (TDD) ?

Issue

The ION meters calculate Total harmonic distortion by default and the user would like to calculate Total demand distortion (TDD) instead.

Product line

ION 7550/7650 PM8000 ION 8650/8600 ION7330/ION7350

Environment
ION Setup 3.0

Resolution
Total demand distortion as defined in the IEEE 519 standard is he total root-sum-square harmonic current distortion, in percent of the maximum demand load current and can be calculated using the following formula :

The IL above is peak or maximum demand load current at the fundamental frequency component measured at the point of common coupling (PCC) derived from the 15 minute or 30 minute billing KVA. With the load already in the system, you can calculate IL as the average of the maximum demand current for the preceding 12 months. for a new installation, you can estimate IL by using predicted load profiles.

One can either setup the ION meter to record the maximum demand current or we can input a calculated value as following:
  1. Navigate the ION meter in advanced mode ( ctrl + alt + left click)
  2. Select the maximum modules folder and then insert a new maximum module
  3. The source should be the sliding demand current input as shown below.
  4. Change the output register’s name to make it easier to link and then create maximum modules for I b/ I c current demand accordingly.
  5. Navigate to harmonic measurements module and then link the Max Demand input to the output of the maximum module created in step 2.
  6. In the setup tab, change the display mode to “MAGNITUDE OUTPUTS DISPLAYED AS PERCENTAGES “ and the THD display mode to Percentages.
If the IL is to be calculated, one can input a constant using an arithmetic module as following:
  1. Navigate to arithmetic modules and insert a new module
  2. Link Source1 to I a mean from the sliding demand window modules.
  3. In the setup tab, change formula one to the constant calculated in Amps
  4. Change the Output register’s name to make it easier to link.
  5. Navigate to harmonic measurements module and then link the Max Demand input to the output of the arithmetic module created created in step 2
  6. In the setup tab, change the display mode to “MAGNITUDE OUTPUTS DISPLAYED AS PERCENTAGES “ and the THD display mode to Percentages
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