Latching relays are electromagnetically operated devices. The E290 range from ABB can be used to realise a simple, energy saving and efficient lighting control system. These devices are mainly used in private houses, factory premises and commercial and public buildings as well as in industrial plants. As a rule, latching relays controlled by means of impulse buttons are installed where it is necessary for lighting to be operated from at least three different places. Each time a command is initiated (by means of an impulse button), an electrical pulse is applied to the coil of the latching relay. The coil in the device is briefly energised and activated. That short pulse to the coil leads to the mechanical latch of the internal main contacts. The internal switching mechanism enables us to achieve a safe and reliable interlock (in the same way as a ballpoint pen). Each pulse that is sent to the magnetic coil system switches the device to its previous position where it is held mechanically until the next control pulse is received. The devices are designed for rated currents 16 and 32A. Through the combinable accessories the main modules can be used in nearly all market applications.