121009-0754 EDT
For an AC solenoid remove the armature (plunger), measure the coil inductance at desired excitation frequency, calculate the inductive reactance, ignore the resistive component, and from the inductive reactance and excitation voltage calculate the RMS steady state current. This is an approximation for your question. If you want peak instantaneous current multiply by 1.414, but there are other factors that influence the result, such as turn on point in the AC voltage waveform and core saturation.
For a DC solenoid peak current is the steady state current calculated from applied DC voltage and the coil resistance. Plunger position is not important. This is why a DC solenoid will not burn out if the plunger is stuck in any position. An AC solenoid will burn out if the plunger is stuck in an open position. But an AC solenoid has a greater initial force than a DC solenoid because of the higher initial current.
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