Generator for electric discharge machining of metallic work pieces by means of an electrode consisting of liquid or solid material

A generator for electric discharge machining of a workpiece with an electrode across a working gap, comprising:

• a principal circuit free from passive output elements and comprising:
• at least two fast electronic switches in circuit between a machining current source and said gap,
• a respective diode in series with each switch, said principal circuit passing machining current working pulses through said gap for respective working pulse durations and with respective working pulse intervals between said working pulses,
• a sensing element operatively connected to said gap and monitoring current strength for each of said working pulses, and
• comparator means connected to said sensing element and acting upon one of said switches in response thereto for terminating a working pulse in response to said sensing element;
• and
• a control circuit for said principal circuit and including:
• a preprogrammed memory storing information representing status of pulses in said gap,
• interrogation means interrogating each of said working pulses a plurality of times during each working pulse duration and comparing a parameter of the interrogated working pulse with a value representing pattern of development of a working pulse, said interrogation means including means for addressing said memory, and
• means connected to said memory and effective upon addressing thereof to control one of said switches and inhibit application of a working pulse to said gap only upon undesired development of said pattern.