def instoc(Imin, CTR=1, Ki=0.5):
    """
    Instantaneous OverCurrent Pickup Calculator.

    Using a sensetivity factor and the CTR, evaluates the secondary-level pickup
    setting for an instantaneous overcurrent element.

    Parameters
    ----------
    Imin:       float
                The minimum fault current in primary amps.
    CTR:        float, optional
                Current Transformer Ratio, default=1
    Ki:         Sensetivity factor, default=0.5

    Returns
    -------
    Ipu:        float
                The pickup setting for the instantaneous
                overcurrent element as referred to the
                secondary side.
    """
    # Evaluate Overcurrent Pickup Setting
    Ipu = Ki * abs(Imin) / CTR
    return Ipu