def relative_ageing_rate(WHST):
    """ Calculate the relative ageing rate of the transformer for a given
    Winding Hotspot Temperature As per AS60076.7 Eq. (2)
    Applies to non-thermally upgraded paper only
    """
    try:
        V = 2 ** ((WHST - 98.0) / 6)
    except OverflowError:
        V = 10000000.0
    return V
