1 Scope
This document specifies additional requirements for single-phase inverter resistance welding transformers with built-in rectifier for DC welding according to ISO 5826.
This document applies to transformers intended primarily for use in welding tongs with an operating frequency of 1 000 Hz and a rated input voltage of 500 V or other voltage values.
If this document has not been amended, the requirements of ISO 5826 also apply.
2 Normative references
The contents of the following documents constitute essential provisions of this document by means of normative references in the text. Where a reference is dated, only the version corresponding to that date applies to this document; where a reference is not dated, the latest version (including all amendment sheets) applies to this document.
ISO669 Resistance welding - Resistance welding equipment - Mechanical and electrical requirements
ISO 5826 Resistance welding equipment - Transformers - General specifications applicable to all transformers
ISO 17677-1 Resistance Welding Vocabulary - Part 1: Spot projection and seam welding
IEC 60417:2002 Graphical symbols for use on equipment
3 Terms and definitions
The terms defined in ISO 669, ISO 5826 and ISO 17677-1 and the following terms and definitions apply to this document.
4 Supply of the transformer-rectifier unit
The rated input voltage shall be supplied by an inverter which shall provide a rated voltage at a frequency of 1000 Hz with a waveform adapted to the characteristics of the transformer-rectifier unit.
5 Type of transformer
The main electrical properties of the transformer-rectifier unit shall be at least as specified in Table 1.
6 Dimensions
The dimensions of the transformer-rectifier unit shall comply with the provisions of Table 2 and are shown in Appendix B.
7 Additional equipment
7.1 Grounding measures
The transformer shall be provided with an earth terminal connected to its housing. The midpoint of the secondary winding shall be connected to the earth terminal by a removable connection.
7.2 Thermal protection
The primary and secondary windings of the rectifier and transformer shall be equipped with a thermal switch. The position of the wiring shall be in accordance with Figure B.1 to Figure B.6.
The colour of the wiring shall be in accordance with the following:
Thermal switch on the primary winding: light blue;
Thermal switch on the secondary winding: black;
Thermal switch on the rectifier: yellow.
Note: Additional requirements are given in ISO 5826.
7.3 Output current induction coils
If the transformer-rectifier unit is equipped with an output current sensing coil, it shall comply with ISO 5826.
7.4 Output voltage transmitter line
If the transformer-rectifier unit is equipped with an output voltage transmitter cable, the wiring markings shall be red and dark blue. The red wire shall be connected to the "10" output terminal and the dark blue wire to the "1" output terminal.
The system should be protected against short-circuits in the transmitter line by suitable means, e.g. by fuses, resistors or positive temperature coefficient thermistors.
If resistors or positive temperature coefficient thermistors are used, a resistance value of 1000 should be used.
8 Rectifier protection
The rectifier should be protected against build-up of welding spatter and other contaminants.
9 Identification
9.1 Primary
The voltage and earth connection terminals shall be clearly marked: U, V and the symbol "" in accordance with IEC 60417:2002.
The connection terminal at the midpoint of the transformer should be marked "MP".
9.2 Outputs
The transformer and the technical documentation shall be marked with the polarity symbols "ten" and "one" for the output terminals in accordance with the requirements of Figures B.1 to B.6.
9.3 Nameplate
The nameplate shall comply with ISO 5826 and the number of this document (GB/T 41136- -2021) shall be marked in column 4 of the marking section.
10 Codenames
The designation shall give information in the following order:
a) Standard number (GB/T 41136- 2021);
b) the type of transformer-rectifier unit (e.g. "H1");
11 Test conditions
11.1 Type test
If this document has not been revised, the type test shall be carried out in accordance with the test methods in ISO 5826 in the following order:
a) General visual inspection (preliminary);
b) insulation resistance (preliminary test);
c) DC no-load voltage, U, no-load input current, I1o;
d) Minimum output current under load;
e) Temperature rise test;
f) Dynamic characteristics;
g) Calibration of current induction coils (where applicable);
h) Insulation resistance ;
i) mechanical strength;
j) transformer-rectifier unit dielectric strength test;
k) cooling circuit;
|) General visual inspection (final).
The reference bandwidth of the instrument for measuring current and voltage systems shall be not less than 100 kHz (3 dB) and the accuracy class shall be 0.5% of the upper limit of the full scale.
For pyrometers, the accuracy class shall be 0.5% of the full scale.
11.2 Example test
The routine test shall consist of a simplified set of tests only:
General visual inspection;
Dielectric strength test;
DC no-load voltage, Uza;
cooling circuit.
11.3 Test procedure
11.3.1 General visual inspection
A visual inspection shall be carried out to assess the visible defects. The visual inspection at the end of the type test procedure shall include measurement of the transformer-rectifier unit dimensions and a report shall be issued. The visual inspection shall include the measurement of the transformer-rectifier unit dimensions and a report.
11.3.2 No-load test
The test shall be carried out in accordance with the requirements of ISO 5826.
11.3.3 Minimum output current under load
The test shall be carried out in accordance with ISO 5826 with a nominal load resistance value of 200μn. The output current I2R shall not be less than the minimum output current under load in Table 1.
11.3.4 Cooling circuit test
The cooling fluid shall not exceed 100 kPa (1 bar) at nominal flow Q for J1, J2, H, N and P units and 160 kPa (1.6 bar) for J3, J4 and S units.
During the type test the cooling circuit should be subjected to a sealing test at a pressure of 1 000 kPa (10 bar) for 10 minutes. This test is not carried out during the routine test.
Passage is determined by a seal and flow check.
11.3.5 Dynamic characteristics of the output
The transformer-rectifier unit shall be capable of withstanding dynamic loads resulting from repetitive welding currents or test currents of not less than three times the secondary continuous output current I2p, in the test arrangement shown in Figure 1.
The load duration shall be 1% and the test time shall be 60 ms.
The number of test cycles shall be 2,500.
The dimensions of a should be measured before and after the test. The deformation of the output terminals should not cause a dimension to change by more than 20%.
11.3.6 Mechanical properties
The transformer shall be fixed between the two plates by means of four M8 or M10 screw holes in the two plates and then the maximum tension of 10 kN shall be reached after 1 min and maintained for a further 1 min. The test shall be repeated on the other two sides of the transformer.
The transformer shall not be permanently deformed or visibly damaged after the test.
Appendix A (informative) relationship between output current and load duration
Appendix B (normative) Transformer dimensions
Bibliography
Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Supply of the transformer-rectifier unit
5 Type of transformer
6 Dimensions
7 Additional equipment
8 Rectifier protection
9 Identification
10 Codenames
11 Test conditions
Appendix A (informative) relationship between output current and load duration
Appendix B (normative) Transformer dimensions
Bibliography
