# Boundary Conditions: Electric Potential

## Function:

Applies an electric potential.

## Application:

Line, Surface.

## Description:

The electric potential is a scalar value. The definition of the electric potential can be done in five difference ways: Forced, Ground, Floating, Loaded, and Transient.
- Forced: Enter values to define the Amplitude (A) and Phase (P) of the forcing function. In a harmonic problem with losses, the forcing function is in the form A × sin (ω × t + P). In a harmonic problem without losses, the forcing function is in the form A × sin (ω × t). In the case of a static problem, the potential is set to A.
- Ground: Defines a zero potential (or reference potential). It is equivalent to a Forced potential with A = 0.
- Floating: The electric potential has the same value over the selected region. An Identifier, i.e. an integer between 0 and 9, allows defining up to 10 different floating potentials in the model.
- Loaded: Same as Floating, with the addition of an external electric load connected to that region. The load is defined with a Resistance value (R) and a capacitance value (C). The external load is connected to the model on one side, and to the ground on the other. The impedance od the load is R + 1/ (j × ω x C).
- Transient: Same as Forced, but the excitation function is time-dependend (good only for Transient analyses). Please see the ATILA User's Manual for details about the various waveforms (sine, raised cosine, step, pulse, external). The External waveform (user-defined) is not implemented yet.

## Remarks:

The electric potential is expressed in volts.

## Illustration:

## ATILA Equivalent:

- For a Ground condition, the ATILA equivalent is a boundary condition (after the END command) in the format -N 4 0, where N takes the values of all the nodes where the condition was applied.
- For a Forced condition, the ATILA equivalent is a line in the EXCITATIONS section in the form M ELECPOT RE IM, where M is one of the nodes of the region where the condition was applied, and RE = P × cos (P) and IM = P × sin (P) are the real and imaginary parts of the forcing function. Additionally conditions are placed after the END command in the form N 4 M, where M is the number of the excitation node and N takes the value of all the other nodes of the region.
- For a FLoating condition, the condition is written after the END command, in the form -N 4 -M, where N and M are both numbers of nodes of the region where the condition was applied.
- For a Loaded condition, it is the same than floating. In addition, the IMPEDANCE command is written, and, at the bottom of the file, a list of resistance and reactance values is written for all frequencies of the harmonic problem.
- For a Transient condition, the same format than for forced is adopted. The difference is that RE and IM have different meaning depending on the time-dependent waveform. Please refer to the ATILA User's Manual for more details.

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