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We present results of our study of the long-period eclipsing binary star NNDelphini (hereafter NN Del). The results are based on spectral data obtainedwith the HRS echelle spectrograph of the Southern African Large Telescope(SALT). Our constructed velocity curve is based on 19 spectra obtained between2017 and 2019 years and covers all phases of the binary's orbit. The orbitalperiod, P=99.252 days, was determined from our spectral data and coincides withthe period determined in previous studies, as well as the system eccentricityof $e=0.517$. Calculated velocity amplitudes of both components allow us todetermine the masses of both system components M_1 = 1.320 M_sun and M_2 =1.433 M_sun with the accuracy about of one percent (0.8% and 1.1%),respectively. Luminosities of both components are presented as L_1 = 4.164L_sun and L_2 = 6.221 L_sun, and the effective temperatures of both componentswere directly evaluated (T_eff = 6545~K and T_eff = 6190~K) together with themetallicity of the system [Fe/H] = -0.19 dex and its color excessE(B-V)=0.026~mag. Comparison with evolutionary tracks shows that the system ageis 2.25+/-0.19 Gyr, and both components are on the main sequence and have notyet passed the turn point. Spectral type is F5V for the hotter component andF8V for another one.

Long-period eclipsing binaries: towards the true mass-luminosity relation. II. Absolute parameters of the NN Del system