1. An electric-arc trainer for welders, said electric-arc trainer comprising: a welding electrode simulator having a first input to which a supply voltage is applied, and a second input to which a signal is applied to control a simulated electrode-melting rate depending on a running length of an arc gap; a welding power source having a first output connected to said first input of said simulator for applying the supply voltage to said simulator, a second output for ensuring together with said first output that welding current is running, and a third output at which a signal is produced to indicate the current arc gap length; a welding object simulation unit having an input connected to said second output of said welding power source; said welding electrode simulator interacting with said welding object simulation unit to produce a welding arc; a control unit having a first input, a second input, a first output, and a second output; said control unit producing sound signals received by the trainee to indicate if the simulated welding process is being run normally and counting the factors selected from a group including the number of errors made by the trainee, the operating time of the simulated welding process, the total time of the simulated welding process, the time of the simulated welding process without errors, and the weld-on time of the welding electrode simulator, and indicating at least one of said factors; said first input of said control unit being connected to said third output of said welding power source; said first output of said control unit being connected to said second input of said welding electrode simulator, and at which the signal is formed to control the simulated electrode-melting rate, depending on the running length of the arc gap; a unit monitoring parameters of the welding process, having an input to which the signal of the current arc gap length is applied, said input being connected to said third output of said welding power source and an output connected to said second input of said control input, at which output the signals are formed to correspond to the values of respective parameters of the simulated welding process; a helmet connected to said second output of said control unit at which signals are formed to provide feedback sound signals to inform the trainee if the welding process is correct.