Transformer protection system with hydraulic temp. loading simulator - uses one or several mutually separated closed hydraulic systems each having at least two sensors

摘要

A transformer protection system uses a hydraulic simulator for temperature loading. It is supplied to transformers supplying LV systems. The hydraulic simulator is used to model the temperature conditions of critical parts of the transformer, such as the windings, in relation to the loading and cooling factors, so as to test utilise the installed transformer capacity. One, or several, mutually separated, closed hydraulic systems are used, each of which has at least two sensors. One sensor is in thermal contact with the transformer oil, while the second sensor is directly or indirectly heated by the expanding liquid in a membrane (6) so that the membrane acts on the electrical switching mechanism when a predetermined, adjustable threshold value is reached. The switching mechanism can be single-pole or multi-pole and provided with working or cooperating contacts, switch-over or blocking contacts, and so connected into the protection circuit of the transformer, that load-shedding or switch-off the transformer is brought about.