import math


def inst_top_oil_rise_at_load(dTOi, dTOult, t, k11, Tau):
    """ Calculate the instanous top oil rise at a given time period
    """
    # As per AS60076.7 Eq. (2)
    dTO = dTOult + (dTOi - dTOult) * math.exp((-t) / (k11 * Tau))

    return dTO