Downhole Power Adapter Sub (EPAT) The Downhole Power Adapter Sub (EPAT) is designed to provide high current to the downhole instrument string. The EPAT reduces the damage to the cable by high currents, as well as reduces the loss of the current over the cable. The EPAT provides 180VAC, and a current of 1.8A to the bottom electric imaging instrument. It can also be used in regular instrument strings which operate on 180VAC with a maximum current of 2.3A.