Abstract: The disclosure relates to a sensor apparatus and a method for measuring the flow rate of a shielding gas in a welding apparatus. The sensor apparatus comprises at least one inlet and at least one outlet in fluid connection with one or more bypass channels and with one or more sensor channels, and at least one input hose and one output hose. The apparatus also comprises one or more thermal mass flow sensors connected to the one or more sensor channels, and a control unit configured to retrieve sensor responses from the one or more thermal mass flow sensors and to determine the flow rate of the shielding gas through the sensor apparatus based on the retrieved sensor response and calibration data, wherein the calibration data comprises one or more characteristic curves comprising gas flow values and sensor response values.

Abstract: The object of the invention is a battery-operated welding and/or cutting device including a frame and at least one battery cell. The frame includes a cooling profile having an outer surface, which is in direct contact with the air surrounding the device. The cooling profile is provided to accommodate at least one battery cell, such that the cooling profile at least partly surrounds the battery cell in order to conduct heat from the battery cell to the cooling profile and, via the outer surface of the cooling profile, away from the device. The object of the invention is also a cooling profile.

Abstract: The present invention concerns a half-bridge inverter and a method for controlling such a welding inverter which has a nominal output power P.sub.n and a nominal operating angular frequency .omega..sub.t, the inverter being comprised of a DC power source (E); of a capacitor configuration comprising at least one capacitor (C.sub.n), the circuit being connected at its first end to one end of the DC power source (E) and at its other end to a point A; of two switching elements (T.sub.1, T.sub.2) connected in series over the DC power supply (E), the switching elements being capable of controlling the pulse width .tau. of the current to the welding load, and thus the power to the welding load, whereby .tau..sub.max determines the nominal power output of the inverter; and of a transformer primary (L.sub.p) connected at its first end to point A and at its second end to the center point of the switching elements (T.sub.1, T.sub.2), and the current switched through the primary has a peak value I.sub.i.

Abstract: The present invention relates to a method for measuring the free wire length in hot-arc or short-arc MIG/MAG welding by making use of the typical behavior of the current or the voltage in the bead short-circuit situation, in which the voltage rises in different ways depending on the free wire length. The phenomenon can be used for measuring the free wire length.

Abstract: An improved D-C to A-C inverter circuit is provided including push-pull sequentially activated thyristor switches connected across a center-tapped D-C voltage source with a saturable reactor connected in series between each thyristor and the center-tap return branch and at least one saturable reactor connected in the center-tap return branch to effectively reduce peak operating voltages.

Abstract: Disclosed is a coupling arrangement of a DC welding apparatus, particularly intended for MIG welding. The coupling comprises a controllable fast DC voltage source, first circuit elements for detecting both load current and load voltage and for generating voltage signals corresponding thereto, second circuit elements for forming a control signal in response to said voltage signals so as to correspond to the values of desired current step and current increase rate in a drop short-circuit instance, and third circuit elements which receive the control signal and effect control of the voltage source in response thereto. Said second circuit elements may include means for receiving a setting signal by which the characteristic values of the current step and the current increase may be set and scaled and the open circuit-voltage of the voltage source can be determined.