IEC 60974-13:2021 pdf download

IEC 60974-13:2021 pdf download.Arc welding equipment – Part 13: Welding current return clamp
6 Designation
The WELDING CURRENT RETURN CLAMP shall be designated by the range of cross-section area of the welding cable intended to be connected. The test current is given in Table 1 based on maximum cross-section area. The WELDING CURRENT RETURN CLAMP shall accept the minimum cross-sectional area as given in Table 1. Minimum cross-sectional area may be reduced to extend the WELDING CURRENT RETURN CLAMP fitting range.
7 Protection against electric shock – Voltage drop
The WELDING CURRENT RETURN CLAMPS in the new condition shall be capable of satisfactorily passing the voltage test. Conformity shall be checked by the following test: Two WELDING CURRENT RETURN CLAMPS are required for this test. Connect each clamp to a cable of maximum cross-sectional area as indicated in Table 1, by using the method of attachment for which the clamps are designed. Attach one clamp to each end of a clean mild steel plate 300 mm × 75 mm × 12 mm. The two clamps shall be positioned so that the centers of the contact points are 260 mm ±20 mm apart. Connect the other end of the cables to a power source to form a circuit. Pass the test current through both clamps and the plate. The voltage is measured on the two cables, at a distance of 10 mm from the cable connections. The voltage drop shall not exceed 0,08 V per 100 A of the test current.
8 Thermal rating
8.1 Temperature rise The temperature rise caused by the current passing through a WELDING CURRENT RETURN CLAMP normally coupled and fitted with an untinned copper welding cable of maximum cross-sectional area as indicated in Table 1 shall not exceed: a) at the hottest spot of the external surface normally gripped by the operator: 40 K; b) at the connection of the welding cable to the WELDING CURRENT RETURN CLAMP : 45 K. NOTE These values are temperature rises in relation to the ambient air temperature (maximum 40 °C). Conformity shall be checked by the following test: Voltage drop set-up given in Clause 7 is used for this test. Before beginning the test, pass the test current through the WELDING CURRENT RETURN CLAMP for a period of 1 h. Allow the WELDING CURRENT RETURN CLAMP to cool to ambient temperature. A DC current equal to the 100 % duty cycle test current given in Table 1 is passed through the WELDING CURRENT RETURN CLAMP until the rate of the temperature rise does not exceed 2 K/h. During the total test time, the DC current shall be kept constant with a tolerance of ± 2 %. 8.2 Resistance to hot objects In the case of insulated WELDING CURRENT RETURN CLAMP , the insulation shall be capable of withstanding hot objects and the effects of a normal amount of weld spatter without being ignited. Conformity shall be checked with a device in accordance with Figure 1.The heated rod in a horizontal position is then applied for 2 min to the insulation. The heated rod shall not penetrate through the insulation and contact live parts. An attempt is made to ignite any gases which may be emitted in the region of the contact point by means of an electric spark or small flame. If the gases are flammable, the burning shall stop as soon as the heated rod is removed.
9 Mechanical requirements
9.1 R ETAINING MEANS A WELDING CURRENT RETURN CLAMP shall be designed to maintain sufficient electrical contact in normal service and to prevent the unintentional separation of the WELDING CURRENT RETURN CLAMP as a result of a longitudinal pull. Where springs are incorporated in the WELDING CURRENT RETURN CLAMP , they shall not constitute part of the current path unless they are permanently by-passed by a fixed conductor capable of carrying the test current given in Table 1. Conformity shall be checked by visual inspection and the following test: A WELDING CURRENT RETURN CLAMP is fitted in accordance with the manufacturer’s instructions, with a welding cable of maximum cross-sectional area 5 m length and its coupling device. The welding cable is folded to form a bundle not exceeding 0,4 m in length. The clamp is attached to a clean mild steel plate 3 mm thick. The steel plate is positioned such that the cable bundle applies a vertical longitudinal force on the clamp for 1 min. Test is passed if the WELDING CURRENT RETURN CLAMP remains attached to the steel plate.