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Modeling Motor/MEQ Connections With Disconnects or VFDs

How do I model a circuit that feeds a disconnect or variable frequency drive (VFD), which then feeds a piece of mechanical equipment (MEQ), such as a motor?​

There are three different methods you can use to model connections between MEQ/motors and intermediary devices like a disconnect or VFD in Revit. Each method has its own use case and limitations, detailed below.

Model the Intermediary Device & MEQ as a Single Device​

Model the intermediary device and MEQ as a single device in Revit. This method is the simplest solution, allowing you to easily:

  • circuit both devices,
  • have the OCP and feeder size based upon FLA, MCA, and MOCP settings when needed,
  • and display them accurately on the single-line diagram.

On the single-line diagram, insert the device using the Insert Link, Copy Link, or Generate commands. For the intermediary, create a custom graphic for the device that includes both parts, or use the Add/Modify Graphic command to add a disconnect graphic to the feeder.

Limitations​

  • You may need to set up an accurate model family for the combined device.
  • You may not be able to define all of the necessary information, such as details of the feeder between the intermediary device and MEQ.

Circuit the Devices in Series​

Model the intermediary device as an Electrical Equipment with the Part Type ▾ set to Panelboard or Switchboard. Circuit the intermediary to the panel, then circuit the MEQ to the intermediary. This method is useful when you need to set information for each device independently and for the feeder between the devices.

On the single-line diagram, insert the intermediary device and MEQ as normal using the Insert Link, Copy Link, or Generate commands.

Limitations​

  • The Revit Supply From parameter on the MEQ will show the intermediary device and not the panel actually feeding it.
  • If the OCP and feeder for the MEQ are sized based upon the FLA, MCA, and MOCP settings on the equipment, that configuration will not extend to the intermediary. You will need to size the OCP and feeder for the intermediary manually.
  • In large projects, defining every intermediary device as an Electrical Equipment can bloat the device lists in the Panel Edit and Circuit Edit commands.

Circuit the Devices in Parallel​

Model the intermediary device and MEQ as separate branch circuit devices. Assign them to the same circuit on the panel. This method is useful when you need the intermediary and MEQ to be modeled separately, but also need the Revit Supply From parameter on the MEQ to show the panel feeding it.

On the single-line diagram, follow these steps:

  1. Insert the intermediary device and MEQ using the Insert Link, Copy Link, or Generate commands. They will be inserted downstream of the panel with separate feeders.
  2. Use the Revit Move command to move the MEQ where you want it to be relative to the intermediary.
  3. Redraw the feeder for the MEQ using one of the following methods:
    • Erase the original feeder, then redraw a dummy feeder by running the Circuit Insert command and pressing ESC. The resulting feeder will not be connected to anything in the model, but can be customized before drafting.
    • Redraw the original feeder by running the Feeder Manual Draw command. When you select the MEQ and are prompted to delete existing feeder segments, select . The resulting feeder will include default graphics for the feeder ID and OCP, but can be modified and will be connected to the circuit in the model.

Limitations​

  • You may not be able to define all of the necessary information, such as details of the feeder between the intermediary device and MEQ.
  • If one or both devices have their OCP and feeder sized based upon FLA, MCA, and MOCP settings on the device, those settings may conflict. You will need to reconcile those settings on both devices.
  • When the devices are inserted on the single-line diagram, they will be inserted as parallel devices on the same circuit to reflect their connection in the model. You will need to modify the single-line manually to show how the devices will actually be connected.