Basic function principles
The EL2212 uses the principle of pulse width modulation with an inductive switching load in order, in three phases, to
- switch the load with increased excitation current in the switch-on phase, "Boost-on phase"
- hold the load with a holding current significantly below the excitation current
- switch the load off in the switch-off phase with counter current if necessary, “Boost-off phase”
By means of the overexcitation, both the response time and the release time resulting from the mechanical inertia of the actuator as well as the delaying influences of the electromagnetic excitation are reduced.
The reduced holding current results in less dissipated heat being produced in the load, while the magnetic energy contained in the inductive actuator is considerably reduced. Hence, the switch-off can take place faster. The relationship is square, i.e. if the holding current is 50% of the rated current, energy only needs to be dissipated from 25% when switching off.
 | Selection of the actuator Against the background of Ohm's law, V = I x R, and the limitations of use of the EL2212 (see the following table and technical data), the actuator is to be selected according to internal resistance and rated operating voltage in such a way that a temporal acceleration of switching is made possible by the overexcitation.
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