TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The electrical conductor is completely or partially engaged through the end plate. The contacting plate has a projection facing the side of the end plate and extends along the end plate. The projection is at least partially engaged into a first cavity of the end plate. The electrical conductor contacts with the contacting plate within the cavity on the projection. The electrical conductor and the contacting plate are cohesively connected, preferably by a welding connection or a soldered connection. The contacting plate has an extension to form the electrical conductor by parallelly protruding on a planar surface of the end plate. The projection is designed as flexible tab. The contacting plate is formed as a metal sheet. The planar surface perpendicular to the plane of the contacting plate has specific material thickness of 0.1-8 mm, preferably 0.5-1 mm. The contacting plate and the end plate are arranged with a sealing assembly having a second cavity (24) on the end plate and a sealing ring (25) partially captured in the second cavity. One of the end plate facing the front side of the contacting plate is formed on at least area of the seal assembly such that the sealing ring is arranged in a plan parallel to the surface plane of the contacting plate to displace the end plate relative to the contacting plate n the contacting plate. The end plate and the contacting plate mutually face a contact area which is formed during operation of the system, when the end plate is arranged perpendicular along the planar surface and the contacting plate aligned along the pressing direction such that the pressing force acting along the pressing direction is primarily introduced through the contact areas and not through the sealing assembly. The end plate and the contacting plate are provided with an opening to pass a medium, preferably at least one of process gas, reaction product and coolant. The sealing assembly seals the opening. The contacting plate and the separator plate half are cohesively connected to one another, preferably by the welded connection or an adhesive connection. At least 80%, preferably at least 90% of the end plate facing the front side of the contacting plate is planar. The contacting plate has a channel to guide the coolant and placed facing rear surface of the separator plate half. The contacting plate is formed as a stamped portion embossed with second deformation. The second deformation on at one of the separator plate half facing the rear surface of the contacting plate forms the channel. The contacting plate facing an inner side (2b) of the end plate has at least one third deformation which is formed such that the at least one third deformation accommodate the second deformation, when the end plate and the contacting plate are pressed. The separator plate half facing away from the rear side of the contacting plate has the channel to guiding the medium, preferably process gas or reaction product, at least one opening to pass the medium, preferably a passage for the coolant, and a bead to seal the opening. The bead has an intermediate space, and an opening arranged corresponding to the opening of the separator plate half. The separator plate half is arranged on the surface area of the contacting plate. The separator plate half and the separator plate are substantially equal. Multiple separator plates are lying between the stack end plates and two end plates adjacent to stack end plate and. The electrochemical system is a fuel cell system, an electrochemical compressor or an electrolyzer.