On board the prototype of DKZ4, with its original GTO-VVVF sound (using the <a href="//commons.wikimedia.org/wiki/File:RG644-A-M_traction_inverter_sign_on_DKZ4_(20211228132307).jpg" title="File:RG644-A-M traction inverter sign on DKZ4 (20211228132307).jpg">RG644-A-M</a>, also known as ATR-M4180-RG644A, inverter).
<a href="//commons.wikimedia.org/wiki/User:N509FZ" title="User:N509FZ">HXD3D-0080</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>