Patent ID: 8662106

Claim:
A hydraulic trip unit for a valve unit in a prime mover plant, the trip unit comprising monitoring passages which are grouped together in a hydraulic block and are interconnected forming a 2-out-of-3 circuit, of which each monitoring passage is provided with a solenoid valve unit; a power oil line connection which is provided on the hydraulic block and from which an emergency oil passage and an auxiliary emergency oil passage extend inside the hydraulic block, of which the emergency oil passage can be connected to the valve unit and the auxiliary emergency oil passage is connected via connecting lines to a solenoid valve unit, wherein a first connecting line feeds a first and third solenoid valve unit, a second connecting line feeds a second and the first solenoid valve unit, and a third connecting line feeds the third and second solenoid valve unit, the auxiliary emergency oil passage and the emergency oil passage are separated from a drain by a plate-type drain valve in such a way that the auxiliary emergency oil passage and the emergency oil passage adjoin the plate-type drain valve with opposite directions of action on a plate of the plate-type drain valve in each case, the plate-type drain valve includes a centrally located leakage orifice which always fluidly connects the auxiliary emergency oil passage to the drain.