NOVELTY - Ensuring and monitoring electrolyzer (1) safety and performances in a manufacturing process, comprises: (a) determining a safe single voltage operation range; (b) determining a reference single voltage deviation; (c) measuring the single voltage over time at the terminals (303, 305) of the electrolyzing cell (2); (d) determining the measured single voltage deviation; (e) comparing the measured single voltage of a cell with the safe single voltage operation range and the measured single voltage deviation of a cell; and (f) stopping the manufacturing process.    USE - The method and system are useful for ensuring and monitoring electrolyzer safety and performances in a manufacturing process which uses at least one electrolyzing cell containing at least one cathode and at least one anode (all claimed).    ADVANTAGE - The method efficiently monitors an electrolysis and determines if individual cells are failing or badly performing.    DETAILED DESCRIPTION - Ensuring and monitoring electrolyzer (1) safety and performances in a manufacturing process which uses at least one electrolyzing cell (2) containing at least one cathode (5) and at least one anode (3), comprises: (a) determining a safe single voltage operation range depending on the current and corresponding to a normally working electrolyzing cell (2); (b) determining a reference single voltage deviation depending on the time derivation of the current; (c) measuring the single voltage over time at the terminals (303, 305) of the electrolyzing cell (2); (d) determining the measured single voltage deviation by calculating the time derivative of the measured single voltage; (e) comparing the measured single voltage of a cell with the safe single voltage operation range and the measured single voltage deviation of a cell with the reference voltage deviation and the measured single voltage deviation of a cell with the average voltage deviation of a group of reference cells over time; and (f) stopping the manufacturing process when the measured single voltage is outside the safe single voltage operation range or the difference between the measured single voltage deviation and the reference voltage deviation is outside a predetermined range or a single voltage behavior is different than the average of a group of reference cells. INDEPENDENT CLAIMS are:    (1) a system (201) for ensuring and monitoring electrolyzer safety and performances in the manufacturing process performed in a manufacturing unit which uses at least one electrolyzing cell (2) capable of carrying out the method above, the system (201) comprising: (i) a set of acquisition and transmission units (203), each of the acquisition and transmission units (203) are configured to measure the single voltage at the terminals (303, 305) of each electrolyzing cell (2) over time according to (c) and to transmit the measured voltage; (ii) a treatment device (205) for collecting the single measured voltage transmitted by each of the acquisition and transmission units (203), configured to implement steps (a), (b), (d) and (e) and to transmit the data to relay means; and (iii) a relay unit (223) configured for implementing step (f) with the data is used from the treatment device (205) and for transmitting an order for stopping the manufacturing process;    (2) a computer program product comprising one or more stored sequences of instruction that is accessible to a processor and which, when executed by the processor, causes the processor to carry out the steps of the method above; and    (3) a computer readable medium carrying one or more sequences of instructions of the computer program product.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the system.    Electrolyzer (1)    Electrolyzing cell (2)    System (201)    Transmission units (203)    Optical fibers (204)    Treatment device (205)    Shutdown system (207)    Metal wires (211)    Terminal fuse protection device (213)    Database and data management unit (215)    Intermediate device (221)    Relay unit (223)