Thermal fuse LS 90
The LS 90 fuse is intended for use in, e.g. boiler houses that use oil as their energy source. There are two LS 90 circuits: for controlling the oil burner and for alarm signaling. In case of fire, the fuse cuts off the control circuit of the oil burner, thus stopping oil feed to the plant. At the same time, the other circuit sets the alarm off.
LS 90 consists of two parts: a contact block and a fuse block. Metal in the fuse block melts at 90°C, the contact block triggering into its alternative state.
Note: never install the LS 90 in a place where the temperature rises above 40°C under normal conditions. The metal used in the fuse softens at that temperature, in the result of aging and may cause a false alarm.