Temperature monitoring apparatus

An apparatus to monitor a temperature or temperature characteristic of a vehicle's electrical energy distribution network is disclosed. The apparatus comprises at least one first optical fibre 50, comprising one or more temperature sensing sections, arranged to produce, in response to an optical input signal, an optical output signal indicative of the temperature of the temperature sensing section. One or more of the temperature sensing sections may comprise a fibre bragg grating. The apparatus may comprise optical director components, d1-d8 to direct the optical input signal to, and/or the optical output signal from the plurality of first optical fibres 50. The optical director components may comprise a passive optical splitter or an active optical switch. An optical interrogator 56 may provide the optical input signal to and receive the optical output signal from the temperature sensing sections of the first optical fibre(s) 50 and may determine the temperatures / temperature characteristics. The apparatus may further comprise feeder optical fibre(s) 54. The electrical energy distribution network may be an aircraft electrical energy distribution network comprising a meshed network of nodes n1-n8, links and internode links 111-115 and 11-19 and a management unit UG to control the flow of electrical energy within the network based on the temperature. The management unit may control one or more active nodes using optical control signals transmitted via one or more optical fibres of the temperature monitoring apparatus. Optical director components d1-d8 may be integrated with nodes n1-n8 of the electrical energy distribution network and the first optical fibre(s) 50 may be embedded in links of the electrical energy distribution network. The management unit UG may control the flow of vehicle's electrical energy within the electrical energy distribution network to reduce or prevent overheating.