def ct_satratburden(Inom, VArat=None, ANSIv=None, ALF=20):
    """
    Current Transformer (CT) Saturation at Rated Burden Calculator
    
    A function to determine the Saturation at rated burden.
    
    .. math:: V_{saturated}=ALF*\\frac{VA_{rated}}{I_{nominal}}
    
    where:
    
    .. math:: VA_{rated}=I_{nominal}*\\frac{ANSI_{voltage}}{20}
    
    Parameters
    ----------
    Inom:       float
                Nominal Current
    VArat:      float, optional, exclusive
                The apparent power (VA) rating of the CT.
    ANSIv:      float, optional, exclusive
                The ANSI voltage requirement to meet.
    ALF:        float, optional
                Accuracy Limit Factor, default=20.
    
    Returns
    -------
    Vsat:       float
                The saturated voltage.
    """
    if VArat == None and ANSIv == None:
        raise ValueError('VArat or ANSIv must be specified.')
    elif VArat == None:
        VArat = Inom * ANSIv / 20
    Vsat = ALF * VArat / Inom
    return Vsat
