NEN EN 60974-1 : 1991

Foreword
1 Scope
2 Normative references
3 Definitions
4 Environmental conditions
5 Test conditions
   5.1 Type tests
   5.2 Routine tests
6 Protection against electric shock
   6.1 Insulation
       6.1.1 Clearances
       6.1.2 Creepage distances
       6.1.3 Insulation resistance
       6.1.4 Dielectric strength
   6.2 Protection against electric shock in normal
       service (direct contact)
       6.2.1 Protection provided by the enclosure
       6.2.2 Capacitors
       6.2.3 Automatic discharge of input capacitors
   6.3 Protection against electric shock in case of a
       fault condition (indirect contact)
       6.3.1 Isolation of the input circuit and the
             welding circuit
       6.3.2 Insulation between windings of the
             input circuit and the welding circuit
       6.3.3 Internal conductors and connections
       6.3.4 Movable coils and cores
       6.3.5 Additional requirements for plasma
             cutting systems
7 Thermal requirements
   7.1 Heating test
       7.1.1 Tolerances of the test parameters
       7.1.2 Duration of the heating test
   7.2 Temperature measurement
       7.2.1 Surface temperature sensor
       7.2.2 Resistance
       7.2.3 Embedded temperature sensor
       7.2.4 Determination of the ambient air
             temperature
       7.2.5 Recording of temperatures
   7.3 Limits of temperature rise
       7.3.1 Windings, commutators and slip-rings
       7.3.2 External surfaces
   7.4 Loading test
   7.5 Commutators and slip-rings
8 Abnormal operation
   8.1 Stalled fan
   8.2 Short-circuit
   8.3 Overload
9 Thermal protection
   9.1 Construction
   9.2 Location
   9.3 Operation
   9.4 Resetting
   9.5 Operating capacity
   9.6 Indication
10 Connection to the input supply
   10.1 Supply voltage
   10.2 Power supply
   10.3 Means of connection
   10.4 Input supply terminals
        10.4.1 Marking of terminals
        10.4.2 Continuity of the protective circuit
   10.5 Cable anchorage
   10.6 Inlet openings
   10.7 Input supply on/off switching device
   10.8 Supply cables
   10.9 Supply coupling device (attachment plug)
11 Output
   11.1 Rated no-load voltage (U[0])
        11.1.1 Rated no-load voltage for use in
               environments with increased hazard of
               electric shock
        11.1.2 Rated no-load voltage for use in
               environments without increased hazard
               of electric shock
        11.1.3 Rated no-load voltage for the use with
               mechanically held torches with
               increased protection for the operator
        11.1.4 Rated no-load voltage for special
               processes e.g. plasma cutting
   11.2 Type test values for the conventional load
        voltage
        11.2.1 Manual metal arc welding with covered
               electrodes
        11.2.2 Tungsten inert gas and plasma arc
               welding
        11.2.3 Metal insert/active gas and
               selfshielded flux cored arc welding
        11.2.4 Submerged arc welding
        11.2.5 Plasma cutting
        11.2.6 Plasma gouging
    11.3 Mechanical switching devices used to adjust
         output
    11.4 Output connections
         11.4.1 Protection against unintentional contact
         11.4.2 Location of socket outlets
         11.4.3 Outlet openings
         11.4.4 Three-phase a.c. multi-operator welding
                transformer
         11.4.5 Marking
         11.4.6 Connections for plasma cutting torches
    11.5 Power supply to external devices
    11.6 Auxiliary power output
12 Control circuits
13 Hazard reducing device
   13.1 Voltage reducing device
   13.2 Switching device for a.c. to d.c.
   13.3 Connection of a hazard reducing device
   13.4 Interference with operation of a hazard reducing
        device
   13.5 Indication of satisfactory operation
   13.6 Fail to a safe condition
14 Mechanical requirements
   14.1 Enclosure
   14.2 Impact resistance of handles, push buttons etc
   14.3 Handling means
   14.4 Drop withstand
   14.5 Tilting stability
15 Rating plate
   15.1 Description
   15.2 Contents
   15.3 Tolerances
   15.4 Direction of rotation
16 Adjustment of the output
   16.1 Type of adjustment
   16.2 Marking of the adjusting device
   16.3 Indication of current or voltage control
17 Instructions and markings
   17.1 Instructions
   17.2 Markings
Annex A (informative) Nominal voltages of supply systems
Annex B (informative) Example of a combination dielectric
                      test
Annex C (normative) Unbalanced load in case of a.c. tungsten
                    inert-gas welding power sources
Annex D (informative) Extrapolation of temperature to time of
                      shutdown
Annex E (normative) Construction of input supply terminals
Annex F (informative) Cross-reference to non-SI units
Annex G (informative) Suitability of input supply for the
                      measurement of the true value of the
                      supply current
Annex H (informative) Plotting of static characteristics
Annex I (normative) Examples of a 10 Nm impact test
Annex J (normative) Thickness of sheet metal for
                    enclosures
Annex K (informative) Examples of rating plates
Annex L (informative) Graphical symbols for arc welding equipment
Figures
Tables

Applies to power sources for arc welding and allied processes designed for industrial and professional use, and supplied by a voltage not exceeding that specified or driven by mechanical means.