On Load Tap Changer Transformer Electrical Panels

OLTC-Transformer Panels

On load Tap Changer (OLTC) is used with higher capacity transformers where HT side voltage variation is frequent and a nearly constant LT is required. OLTC is fitted with the transformer itself. Multiple tapings from HV windings are brought to the OLTC chamber and contacted to fixed contacts. Moving contacts rotates with the help of rotating mechanism having a spindle. This spindle can be rotated manually as well as electrically with a motor. Motor is connected in such a way that it can rotate in both the directions so as to rotate the OLTC contacts in clockwise and antilock-wise direction. Two push buttons are fitted on the LCP (local control panel) to rotate the motor and hence the OLTC contacts in clockwise and anti-clockwise direction. This movement of contacts thus controls the output LV voltage of the transformer. So rotating of OLTC contacts with spindle or push buttons in this way is a manual process. In case this process of rotating the OLTC contacts and hence controlling the LV side voltage is to be done automatically then a RTCC (Remote Tap Changer Controller) is installed with the transformer HT Panel. The RTCC sends signals to LCP and LCP in turn rotates the motor as per the signals received from the RTCC.