IEC 60974-7-2019 pdf free.Arc welding equipment -Part 7: Torches.
The TORCH insulation shall withstand a test voltage without flashover or breakdown.Coronadischarges are permitted.
LIQUID-COOLED TORCHEs may be tested without cooling liquid.
Conformity shall be checked by the following test:
The TORCH HANDLE is tightly wrapped with a metal foil.The cable and hose assembly is placedin contact with a conductive surface throughout its entire length, for example wrapped arounda metal cylinder or coiled on a flat metal surface.The metal foil and the conductive surfaceare electrically connected.
A test voltage with a peak voltage 20 % higher than the rated ARC STRIKING AND STABILIZINGVOLTAGE is applied for 2 s between the TORCH electrode and the conductive surface.Otherisolated circuits may be connected to the TORCH electrode,the conductive surface or leftisolated as specified by the manufacturer. The equipment manufacturer shall conduct a riskassessment of the other isolated circuitry and respective external parts.
Circuits other than the cutting circuit that leave the plasma cutting TORCH may be electricallyconnected to the electrode or isolated during this test,provided that the external parts of theother circuit have reinforced insulation to protect the operator. Additionally, the equipmentmanufacturer shall conduct an appropriate risk assessment and establish a set of measureswhich give sufficient protection against electric shock under single-fault conditions.
This test voltage is either:
a) high-frequency voltage of pulse width between 0,2 us and 8 us, with a repetition frequency between 50 Hz and 300 Hz; or
b) an AC test voltage with the same peak value of approximately sine waveform at 50 Hz or 60 Hz.The maximum permissible setting of the tripping current shall be 100 mA.The highvoltage transformer shall deliver the prescribed voltage up to the tripping current. Trippingis regarded as a flashover or a breakdown.
MANUAL TORCHEs shall be rated at a minimum of 100 % or 60 % or 35 % duty cycle.
MECHANICALLY GUIDED TORCHEs shall be rated at a minimum of 100 % duty cycle.
FUME EXTRACTION TORCHES shall be rated at the extraction flow rate defined by themanufacturer.
8.2Temperature rise
The temperature rise of MANUAL TORCHES, at any point on the outer surface of the part of theHANDLE gripped by the operator, shall not exceed 30 K.
The temperature rise of cABLE-HOSE ASSEMBLY,at any point on the outer surface, shall notexceed 40 K.
After completion of the tests, the safety and operability of the TORCH shall not be impaired.Conformity shall be checked by the heating test according to 8.3.
8.3Heating test
The TORCHEs shall be loaded with all rated currents at their corresponding rated duty cycles,see 8.1.
The mean value of the DC current shall be taken and the electrode polarity shall be chosen inaccordance with 8.3.2 and 8.3.3.
The temperature shall be measured at the hottest spot on the area of the HANDLE,normallygripped by the operator for MANUAL TORCHES.IEC 60974-7 pdf download.