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Feeder Voltage Drop Calculations

This tutorial teaches you how to calculate feeder voltage drop in your project.

The setup required for the voltage drop calculations is the same as for the fault calculation. We recommend you follow the Fault Calculations tutorial first before following this one, even if you are not interested in fault calculations.

Open drawing E-4.2.

Insert the Voltage Drop Schedule​

  1. Run the Insert Voltage Drop Schedule command. The Voltage Drop Current Schedule dialog box will open.
    Ribbon: DM Electrical→Distribution Equipment→  Insert Voltage Drop Schedule
    Pulldown Menu: DM Electrical→Distribution Equipment Schedules→Insert Voltage Drop Schedule

  2. Press the button to close the dialog box.

  3. Follow the prompts at the command line to place the voltage drop schedule on the drawing.

Add Load to a Panel​

You may have noticed that all of the voltage drop values are calculated as 0%. Voltage drop is based upon the load in the system and there are currently no loads defined. In order to see a load, we will add a load.

  1. Run the Panels command. The Panel dialog box will open.
    Ribbon: DM Electrical→Distribution Equipment→  Panels
    Pulldown Menu: DM Electrical→Distribution Equipment→Panels

  2. Go to panel L2. You can do this using the and buttons or the button.

  3. Press the button. The Feeder and Service Calculation Settings dialog box will appear.

  4. Set Metered Demand to 20.

  5. Press the button to close the dialog box.

  6. Press the button to close the dialog box.

  7. Run the Insert Voltage Drop Schedule command. The Voltage Drop Current Schedule dialog box will open.
    Ribbon: DM Electrical→Distribution Equipment→  Insert Voltage Drop Schedule
    Pulldown Menu: DM Electrical→Distribution Equipment Schedules→Insert Voltage Drop Schedule

  8. Press the button.

The voltage drop schedule will be updated in its current location on the drawing. It should display a voltage drop to the panels and transformers.

Voltage Drop Through Transformers​

The voltage drop at transformer T1 is probably very high. That is because the voltage drop through the transformer is included by default. This setting can be changed depending upon how you want to calculate voltage drop through a transformer.

  1. Run the Options→Edit Project List command. The Options dialog box will open.
    Ribbon: DME: Customization→Project Customization→  Options
    Pulldown Menu: DM Electrical→Customization→Options→Edit Project List

  2. In the Distribution Equipment ☰ section, set Voltage drop and transformers ▾ to Ignore transformers.

  3. Press the button to close the dialog box.

  4. Run the Insert Voltage Drop Schedule command. The Voltage Drop Current Schedule dialog box will open.
    Ribbon: DM Electrical→Distribution Equipment→  Insert Voltage Drop Schedule
    Pulldown Menu: DM Electrical→Distribution Equipment Schedules→Insert Voltage Drop Schedule

  5. Press the button.

The voltage drop schedule will be updated in its current location on the drawing. The voltage drop through the transformer should be lower than it was before.

Branch Circuit Voltage Drop​

There are no values displayed for branch circuit voltage drop because there are no light fixtures, receptacles, or equipment in the project. Once those items are inserted and circuited, the voltage drop to them can be calculated. The Branch Circuit Voltage Drop tutorial covers this topic, but it assumes you have followed the preceding tutorials.