A combustion assembly for an electric power plant comprising a combustion chamber , provided with at least a burner assembly , and a fuel supply system for supplying fuel to the combustion chamber ; the fuel supply system comprising at least a feed line provided with: - a manifold supplied with fuel; - at least a connecting pipe , which connects the manifold to the respective burner assembly ; - a connecting element , which connects the connecting pipe to the respective burner assembly and/or the connecting pipe to the respective manifold ; the connecting element being configured to define a quick coupling; wherein the connecting element comprises a male connector and a female connector connectable to each other and shaped so as to define a quick coupling; the combustion assembly being characterized in that the connecting element comprises a security device , configured to avoid accidental uncoupling of the connecting element ; wherein the security device is configured to assume a lock position, wherein uncoupling between male connector and female connector is prevented and to assume an unlock position, wherein uncoupling between male connector and female connector is enabled; the security device comprising a ring arranged externally to the female connector and a lock element , which protrudes from the outer face of the female connector ; the ring having an annular shape and being fitted around the female connector so as to turn about the female connector ; the ring being provided with an annular outer face , with an annular inner face , with an annular rib , which protrudes from the annular inner face substantially at a first external edge of the ring , and with a recess made along a second external edge , opposite to edge ; the security device being configured so as the passage from the lock position to the unlock position is achieved by turning the ring until the recess of the second edge is aligned with the lock element and by moving the ring axially in such a way that the lock element engages the recess . - a manifold supplied with fuel; - at least a connecting pipe , which connects the manifold to the respective burner assembly ; - a connecting element , which connects the connecting pipe to the respective burner assembly and/or the connecting pipe to the respective manifold ; the connecting element being configured to define a quick coupling; wherein the connecting element comprises a male connector and a female connector connectable to each other and shaped so as to define a quick coupling; the combustion assembly being characterized in that the connecting element comprises a security device , configured to avoid accidental uncoupling of the connecting element ; wherein the security device is configured to assume a lock position, wherein uncoupling between male connector and female connector is prevented and to assume an unlock position, wherein uncoupling between male connector and female connector is enabled; the security device comprising a ring arranged externally to the female connector and a lock element , which protrudes from the outer face of the female connector ; the ring having an annular shape and being fitted around the female connector so as to turn about the female connector ; the ring being provided with an annular outer face , with an annular inner face , with an annular rib , which protrudes from the annular inner face substantially at a first external edge of the ring , and with a recess made along a second external edge , opposite to edge ; the security device being configured so as the passage from the lock position to the unlock position is achieved by turning the ring until the recess of the second edge is aligned with the lock element and by moving the ring axially in such a way that the lock element engages the recess . <EOS>