The performance of the Clapham SVC after a control retrofit is describ
ed. The replacement of an analogue with digital control was completed
in 1995. The retrofit was accomplished well within the ten days of all
otted shut down time. With the original control system ac system volta
ge unbalance caused by untransposed lines had to be balanced by manual
adjustment. The primary improvement provided with the new control is
automatic and continuous voltage balancing.