Solenoid control and safety circuit system and method

A method of operating a contact-start plasma arc torch system, said torch system including a torch actuation switch indicating desired operational states of the torch, a power supply having first and second output terminals and selectively supplying an output voltage therebetween, a plurality of contact start elements, a first one of the plurality of contact start elements being in selective electrical communication with the first output terminal, and a second one of the plurality of contact start elements being in selective electrical communication with the second output terminal, said method comprising:

• monitoring the torch activation switch and determining if the desired operational state of the torch transitions from an off state to an operating state;
• closing a gas control switch to allow the plurality of contact start elements to form a closed electrical circuit between said plurality of contact start elements;
• monitoring the output voltage;
• comparing the output voltage to a low voltage threshold;
• opening the gas control switch and providing a flowing gas to be ionized if the output voltage is less than the low voltage threshold;
• and
• comparing the output voltage to a high voltage threshold after opening the gas control switch and thereafter closing the gas control switch and removing the flowing gas if the output voltage is greater than the high voltage threshold.

A method of operating a contact-start plasma arc torch system, said torch system including a torch activation switch having a first state and a second state, a power supply responsive to the state of the torch actuation switch and selectively providing an output voltage, a solenoid selectively allowing a gas to be ionized to flow into the torch, the method comprising:

• determining the state of the torch actuation switch;
• determining a value indicative of the output voltage;
• determining the position of the solenoid;
• opening the solenoid if the torch actuation switch is in the second state and the solenoid is closed;
• and
• closing the solenoid if the torch actuation switch is in the second state and the solenoid is open and the output voltage is greater than an open circuit threshold.

A contact start plasma-arc torch system for use by a torch operator in connection with a workpiece, the torch system comprising:

• a power source selectively providing an output voltage, and wherein said output voltage transitions from a first value to a second value when a contact start operation is initiated;
• a torch head including an electrode and a tip, said electrode positioned in a circuit path with the power source and receiving the output voltage, said tip being adjacent the electrode;
• a source of gas to be ionized;
• a gas supply line;
• a gas control solenoid associated with the gas supply line, said gas control solenoid being positioned between the source of gas and the torch head and selectively allowing gas from the source of gas to flow into the torch head via the gas supply line;
• a gas monitor circuit providing a gas pressure signal having a parameter indicative of a gas pressure in the gas supply line at a point between the gas control solenoid and the torch head;
• and
• a control circuit monitoring the output voltage and the gas pressure signal, said control circuit setting a time delay period when the output voltage transitions from the first value to the second value and causing the output voltage to reset from the second value to a third value if after the time delay period the gas pressure signal is less than a gas threshold.

A contact start plasma-arc torch system for use by a torch operator in connection with a workpiece, the torch system comprising:

• a power source selectively providing an output voltage;
• a torch head including an electrode and a tip, said electrode positioned in a circuit path with the power source and receiving the output voltage, said tip being adjacent the electrode;
• a source of gas to be ionized;
• a gas supply line;
• a gas control solenoid associated with the gas supply line, said gas control solenoid being positioned between the source of gas and the torch head and selectively allowing gas from the source of gas to flow into the torch head via the gas supply line;
• a gas monitor circuit providing a gas pressure signal having a parameter indicative of a gas pressure in the gas supply line at a point between the gas control solenoid and the torch head;
• and
• a control circuit monitoring a differential voltage selectively established between the electrode and the tip, said differential voltage transitioning from a first value to a second value when a contact start operation is initiated, said control circuit also monitoring the gas pressure signal, said control circuit setting a time delay period when the differential voltage transitions from the first value to the second value and causing the power source to remove the output voltage from the electrode if after the time delay period the gas pressure signal is less than a gas pressure threshold.

A contact start plasma-arc torch for use by a torch operator in connection with a workpiece, the torch system comprising:

• a power source selectively providing an output voltage that transitions from a first value to a second value when a contact start operation is initiated by the torch operator;
• a torch head including an electrode and a tip, said electrode positioned in a circuit path with the power source and receiving the output voltage, said tip being adjacent the electrode;
• and
• a control circuit monitoring a differential voltage between the electrode and the tip, said control circuit causing the output voltage of the power source to transition to a third value if the differential voltage between the electrode and the tip remains less than a contact start threshold after a time period sufficient to allow the contact start operation to complete has elapsed.

A power supply suitable for use in connection with a contact start plasma-arc torch system, said torch system including a torch head having an electrode and a tip, a source of gas to be ionized, a gas supply line supplying gas to the torch head, a gas control switch associated with the gas supply line, said gas control switch being positioned between the source of gas and the torch head and selectively allowing gas from the source of gas to flow into the torch head via the gas supply line, and a gas pressure switch providing a gas pressure signal indicative of a gas pressure in the gas supply line at a point between the gas control solenoid and the torch head, said power supply comprising:

• a power source selectively providing an output voltage to the electrode, and wherein said output voltage transitions from a first value to a second value when a contact start operation is initiated;
• and
• a control circuit monitoring a differential voltage selectively established between the electrode and the tip, said differential voltage transitioning from a first value to a second value when the contact start operation is initiated, said control circuit also monitoring the gas pressure signal, said control circuit setting a time delay period when the differential voltage transitions from the first value to the second value and causing the power source to remove the output voltage from the electrode if after the time delay period the gas pressure signal is less than a gas pressure threshold.