HOT-SPOT DETECTION IN ELECTRICAL DEVICES

An electrical device including a surface which may be exposed to heat derived from operation of the electrical device such that the temperature of the surface increases during operation. The surface includes a temperature sensor including first and second electrodes separated by a layer of control material. The material properties and/or configuration of the control material are selected such that the electrical conductivity of the control material increases with increasing temperature so that electrical current is able to pass between the first and second electrodes once the temperature of any part of the control material has reached or exceeded a predetermined temperature. The temperature sensor extends over substantially the whole of the surface. A system including the electrical device and a method of controlling the electrical device is also disclosed.