Ungrad - (Senior Member IEEE) ABB Relays AG. Baden Switzerland

After several years of practical experience with station control systems (SCS) and station monitoring systems (SMS) including control, protection, measurement and even regulation, a comparison can be made between the expectations of the users and the r esults. It is worth noting that these systems have created changes not only in the method controlling, remotely controlling and supervising a substation, but also in the structure of maintenance, of training the operating staff and of studying events, faults, load situations etc.Generally it can be said that these systems allow the storage of much more information concerning fault recording, such as analog and digital values during a fault, distances of the fault, power flow and trends etc.. Furthermore the information concerning the status of the primary equipment enables "maintenance on request instead of a maintenance according to a fixed time schedule, thus saving a lot of time and moneyAt the same time availability is increased. To get the best out of all the available information, training of the operating staff has to be rendered. Some of the standard models are presented.The changes mentioned are demonstrated on existing plants and records.