Piezo transducer current consumption
If you're driving the transducer at resonance, the reactive terms will cancel and all you'll be left with is the resistance.

In this case, if the impedance looks like a pure resistance, then Ohm's law applies and the transducer will draw 

$$ I = \frac {E}{Z} = \frac{170V}{50\Omega} = 3.4 \text { amperes}$$

and dissipate 

$$ P= I^2 R = 11.56 \times 50\Omega = 578 \text { watts}$$