One of the quality of power supply is the quality of voltage received by consumers. The amount of voltage received by the electricity consumer is not the same, this is because of the impedance of the network. Therefore, Voltage Drop is always present on every part of the power system, from source to customer. Fall The voltage is directly proportional to the magnitude of the current and the phase angle, ie the current flowing through the power system. One of the fixtures to keep the service voltage within limits allowed, the distribution transformer is equipped with Off Load Tap Changer on the high voltage side. Based on SPLN NO 1: 1995 ie voltage variation or tolerance of service voltage is +5% and - 10%. So Rasamala penyulang said Good because the value is still under the provisions of 4,648% and tap position used is tap 2.