An apparatus for determining the operating condition of a shaker system that has a vibration controller for controlling a drive coil via an amplifier and by monitoring an acceleration sensor, a variable field current power supply for controlling a field coil, a variable blower power supply for controlling a cooling apparatus, the drive coil that is set in the static magnetic field generated by the field coil and is driven by electromagnetic force, an armature that transfers the force generated at the drive coil to the test specimen, the cooling apparatus being set to cool the field coil and the drive coil, characterized that it also comprises: at least one temperature sensor at the intake of cooling air of the shaker system; means configured and adapted to calculate the necessary excitation force that is the excitation force presently generated by the shaker system, based on information of drive current of the drive coil and from the field coil necessary to yield the desired vibration for the test specimen under condition that a standard field current is fed to the field coil; means configured and adapted to calculate supposed drive current of the drive coil necessary to generate the necessary excitation force under each supposed field current of the field coil, the supposed field current being supposed to be varied from said standard field current; means configured and adapted to calculate supposed temperatures of the field coil to which each of the supposed field current is fed and supposed temperatures of the drive coil to which each of the supposed drive current is fed under each supposed cooling capability of the cooling apparatus; means configured and adapted to select at least one operating condition that is a combination of the supposed field current and the supposed cooling capability under which the supposed temperatures of the field coil and the drive coil will not exceed limitation and a focused operating feature will be satisfied among multiple combinations of the supposed field current and the supposed cooling capability, the focused operating condition being the minimization or the maximization of a particular system parameter, such as system energy, system efficiency or blower noise; means configured and adapted to output the at least one of the operating conditions. at least one temperature sensor at the intake of cooling air of the shaker system; means configured and adapted to calculate the necessary excitation force that is the excitation force presently generated by the shaker system, based on information of drive current of the drive coil and from the field coil necessary to yield the desired vibration for the test specimen under condition that a standard field current is fed to the field coil; means configured and adapted to calculate supposed drive current of the drive coil necessary to generate the necessary excitation force under each supposed field current of the field coil, the supposed field current being supposed to be varied from said standard field current; means configured and adapted to calculate supposed temperatures of the field coil to which each of the supposed field current is fed and supposed temperatures of the drive coil to which each of the supposed drive current is fed under each supposed cooling capability of the cooling apparatus; means configured and adapted to select at least one operating condition that is a combination of the supposed field current and the supposed cooling capability under which the supposed temperatures of the field coil and the drive coil will not exceed limitation and a focused operating feature will be satisfied among multiple combinations of the supposed field current and the supposed cooling capability, the focused operating condition being the minimization or the maximization of a particular system parameter, such as system energy, system efficiency or blower noise; means configured and adapted to output the at least one of the operating conditions.