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    • Introduction
    • General information about the welding circuit
      • Electrical resistance in the welding circuit
        • General
        • Minimum cable cross-section
      • Inductance in the welding circuit
        • Inductance in the welding circuit
        • Inductance for pulsed arcs
        • Measurement of welding circuit resistance and inductance
        • Standard values for possible process interference
      • Magnetic interference of the arc
        • Magnetic arc blow
        • Magnetic arc blow during TWIN welding
        • Demagnetizing with alternating voltage
      • Interference coupling
        • Interference coupling
        • Example: Coupling of two welding circuits in the pulsed arc
        • Measuring the coupling factor
        • Couplings with multiple arcs on one component
    • Structure of the welding circuit
      • Grounding point design
        • General
        • Contact force/surface pressure
        • Separate grounding points
        • Grounding contacts for rotating devices
        • Number of grounding points
      • Notes on welding circuits in manual welding systems
        • Compact welding systems
        • Split welding systems
      • Notes on welding circuits in automated welding systems
        • General
        • Example
        • Further information
      • Welding with multiple arcs on one component
        • General
        • Separating welding circuits
        • Sensor cable for correct voltage measurement
        • Sensor cable for multiple arcs
    • Optimization examples
      • Optimization examples
        • Overview
        • Multiple individual welding systems on one component – before optimization
        • Multiple individual welding systems on one component – after optimization
        • TWIN welding system – before optimization
        • TWIN welding system – after optimization
        • Multiple TWIN welding systems on one component – before optimization
        • Multiple TWIN welding systems on one component – after optimization

    Cable Management Guide Operating instructions

    Introduction
    General information about the welding circuit
    Grounding point design
    Manual welding circuits
    Automated welding circuits
    Multiple arcs on one component
    Optimization examples
    Spare parts

    Introduction

    The influence of the welding circuit cable routing on reproducible welding results is often underestimated.
    Experience shows that errors occur again and again in the system planning, which lead to disruptions in the welding process.
    This cable management guide is intended to assist you in setting up or optimizing welding circuits and their cable arrangements.

    The following points must be considered when planning a welding system:

    1. Keep return lead cables and hosepacks as short as possible – provide only necessary lengths
    2. Ensure good contact at the grounding points
    3. Avoid long current paths in the workpiece
    4. Reduce magnetic and inductive interference:
      • Sufficient distance between two conductors of the same polarity
        Recommendation: > 30 cm
      • If possible, route the welding positive lead and grounding cable together
        or
        Use compensated interconnecting hosepacks
      • Avoid coils and loops in the welding circuit
      • Ensure that as little ferritic material as possible is present in the welding circuit
    5. Separate current paths if several systems are welding at the same time:
      • Do not provide shared grounding rails and grounding cables
      • Avoid crossing the current paths in the workpiece

    Possible setup errors and how to optimize them
    This cable management guide describes possible setup errors and how to optimize them. Details in the "Optimization examples" section starting on page (→)

    Possible setup errors and how to optimize them: e.g., separate current paths

    The influence of the welding circuit cable routing on reproducible welding results is often underestimated.
    Experience shows that errors occur again and again in the system planning, which lead to disruptions in the welding process.
    This cable management guide is intended to assist you in setting up or optimizing welding circuits and their cable arrangements.

    The following points must be considered when planning a welding system:

    1. Keep return lead cables and hosepacks as short as possible – provide only necessary lengths
    2. Ensure good contact at the grounding points
    3. Avoid long current paths in the workpiece
    4. Reduce magnetic and inductive interference:
      • Sufficient distance between two conductors of the same polarity
        Recommendation: > 30 cm
      • If possible, route the welding positive lead and grounding cable together
        or
        Use compensated interconnecting hosepacks
      • Avoid coils and loops in the welding circuit
      • Ensure that as little ferritic material as possible is present in the welding circuit
    5. Separate current paths if several systems are welding at the same time:
      • Do not provide shared grounding rails and grounding cables
      • Avoid crossing the current paths in the workpiece

    Possible setup errors and how to optimize them
    This cable management guide describes possible setup errors and how to optimize them. Details in the "Optimization examples" section starting on page (→)

    Possible setup errors and how to optimize them: e.g., separate current paths

    General information about the welding circuit

    Electrical resistance in the welding circuit

    General

    The welding circuit contains different materials and cross-sections, as well as contact resistances at the coupling points.

    In a series circuit, the resistances add up; large power losses and voltage drops can occur.

    The contact resistances at coupling points vary greatly with the contact force and the surface condition.

    Resistances of the different materials
    depending on length and cross-section

    Resistances of the coupling points
    depending on the contact force

    R1 HP Con

    Interconnecting hosepack

    R C1

    Welding positive lead to power source

    R2 HP

    Torch hosepack

    R C2

    Extension hosepack

    R3 GD

    Return lead cable

    R C3

    Torch hosepack

    R4 WP

    Workpiece, work table

    R C4

    Torch body

     

     

    R C5

    Welding table or clamp

     

     

    R C6

    Welding negative lead to power source

     

     

     

    R

    Total resistance (= sum of all individual resistances)

    1. General information about the welding circuit

    Electrical resistance in the welding circuit

    General

    The welding circuit contains different materials and cross-sections, as well as contact resistances at the coupling points.

    In a series circuit, the resistances add up; large power losses and voltage drops can occur.

    The contact resistances at coupling points vary greatly with the contact force and the surface condition.

    Resistances of the different materials
    depending on length and cross-section

    Resistances of the coupling points
    depending on the contact force

    R1 HP Con

    Interconnecting hosepack

    R C1

    Welding positive lead to power source

    R2 HP

    Torch hosepack

    R C2

    Extension hosepack

    R3 GD

    Return lead cable

    R C3

    Torch hosepack

    R4 WP

    Workpiece, work table

    R C4

    Torch body

     

     

    R C5

    Welding table or clamp

     

     

    R C6

    Welding negative lead to power source

     

     

     

    R

    Total resistance (= sum of all individual resistances)

    1. General information about the welding circuit
    2. Electrical resistance in the welding circuit

    General

    The welding circuit contains different materials and cross-sections, as well as contact resistances at the coupling points.

    In a series circuit, the resistances add up; large power losses and voltage drops can occur.

    The contact resistances at coupling points vary greatly with the contact force and the surface condition.

    Resistances of the different materials
    depending on length and cross-section

    Resistances of the coupling points
    depending on the contact force

    R1 HP Con

    Interconnecting hosepack

    R C1

    Welding positive lead to power source

    R2 HP

    Torch hosepack

    R C2

    Extension hosepack

    R3 GD

    Return lead cable

    R C3

    Torch hosepack

    R4 WP

    Workpiece, work table

    R C4

    Torch body

     

     

    R C5

    Welding table or clamp

     

     

    R C6

    Welding negative lead to power source

     

     

     

    R

    Total resistance (= sum of all individual resistances)

    1. General information about the welding circuit
    2. Electrical resistance in the welding circuit

    Minimum cable cross-section

    The resistance of a current-carrying cable depends on the cross-section, material, and length.
    A high resistance causes a voltage drop and thus a power loss in the welding circuit.

    Adequate dimensioning of the cable cross-sections can counteract this.

    Recommended minimum cable cross-sections for uncooled copper cables and 100% duty cycle:

    Welding current

    Cable length up to 10 m

    Cable length up to 50 m

    150 A

    16 mm²

    25 mm²

    200 A

    25 mm²

    35 mm²

    250 A

    35 mm²

    50 mm²

    300 A

    50 mm²

    70 mm²

    400 A

    70 mm²

    95 mm²

    500 A

    95 mm²

    120 mm²

    600 A

    120 mm²

    2 x 95 mm²

    IMPORTANT! Position and fix components isolated to earth potential to avoid parallel resistances and current flows.

    1. General information about the welding circuit

    Inductance in the welding circuit

    Inductance in the welding circuit

    Every current-carrying conductor generates a magnetic field. If the amperage changes, the changing magnetic field induces a voltage. The voltage counteracts the change in current.
    The inductance corresponds to the resistance to a change in current.

    If the effective area between two conductors increases, the area of the magnetic flux increases and so does the inductance.

    Individual inductances in the welding circuit, which add up to a total inductance

    Inductances

    Calculation of inductances from

    L1

    Inductance of positive pole winding

    N1 

    Number of welding positive lead turns

    L2 

    Inductance of return lead cable winding

    N2 

    Number of welding negative lead turns

    L3 

    Inductance from total area

    A1 

    Welding positive lead winding area

    A2 

    Welding negative lead winding area

     

     

    A3 

    Effective area

     

     

    µr1-µr3

    Permeabilities due to material in the areas

     

     

     

    L

    Total inductance (= sum L1 + L2 + L3)

    The inductance L [µH] increases due to the surrounding materials with their permeability µr and squares with the number of turns N of a conductor.

    With the included area A and the materials µr, the inductance can be approximated using the formula for the ring-shaped air coil µ0:

    N

    Number of turns [1]

    A

    Effective area [m2]

    l

    Conductor length [m]

        

    Magnetic field constant [Vs/Am]
    Physical constant in vacuum (4   x 10-7)

        

    Relative permeability [Vs/Am]
    Magnetizability of a material

    IMPORTANT!
    Do not wind hosepacks and return lead cables!

    1. General information about the welding circuit
    2. Inductance in the welding circuit

    Inductance in the welding circuit

    Every current-carrying conductor generates a magnetic field. If the amperage changes, the changing magnetic field induces a voltage. The voltage counteracts the change in current.
    The inductance corresponds to the resistance to a change in current.

    If the effective area between two conductors increases, the area of the magnetic flux increases and so does the inductance.

    Individual inductances in the welding circuit, which add up to a total inductance

    Inductances

    Calculation of inductances from

    L1

    Inductance of positive pole winding

    N1 

    Number of welding positive lead turns

    L2 

    Inductance of return lead cable winding

    N2 

    Number of welding negative lead turns

    L3 

    Inductance from total area

    A1 

    Welding positive lead winding area

    A2 

    Welding negative lead winding area

     

     

    A3 

    Effective area

     

     

    µr1-µr3

    Permeabilities due to material in the areas

     

     

     

    L

    Total inductance (= sum L1 + L2 + L3)

    The inductance L [µH] increases due to the surrounding materials with their permeability µr and squares with the number of turns N of a conductor.

    With the included area A and the materials µr, the inductance can be approximated using the formula for the ring-shaped air coil µ0:

    N

    Number of turns [1]

    A

    Effective area [m2]

    l

    Conductor length [m]

        

    Magnetic field constant [Vs/Am]
    Physical constant in vacuum (4   x 10-7)

        

    Relative permeability [Vs/Am]
    Magnetizability of a material

    IMPORTANT!
    Do not wind hosepacks and return lead cables!

    1. General information about the welding circuit
    2. Inductance in the welding circuit

    Inductance for pulsed arcs

    When welding with high inductances, rapid current changes can no longer take place at the desired rate of change because the maximum voltage of a power source (= ULimit) is insufficient.
    This is particularly noticeable with pulsed arcs and long hosepacks with high inductances in the welding circuit.

    Low inductance

    High inductance

    Influence of inductance on the current profile of a pulsed arc

    At high inductance, the current actual value Iact does not reach the target current flow Iset due to the limited socket voltage Uclamp.

    High-speed video sequence: Influence of inductance on droplet detachment during pulsed-arc welding

    Sequence A1 - A2:
    desired metal droplet transfer at reduced inductance

    Sequence B1 - B2:
    the pulsed arc pinch force is negatively affected because the current rise ramp is not reached.
    The welding process becomes unstable, droplet detachment is no longer optimal, and a lot of spatter is produced.

    Same settings for sequence A1 - A2 and B1 - B2.

    1. General information about the welding circuit
    2. Inductance in the welding circuit

    Measurement of welding circuit resistance and inductance

    The welding circuit resistance and the welding circuit inductance are determined via the power source in the course of the R/L alignment.

    After positioning the contact tip and starting the R/L alignment, the voltage drop and inductance in the entire welding circuit are determined. The ohmic resistance and the inductance are used to correctly document the arc voltage display and for process control.

    IMPORTANT!
    Always perform an R/L alignment when changing the welding circuit (e.g., change of hosepack)!

    Start R/L alignment:

    1On the power source, select:
    Process parameters / Common / Next page / R/L-check / alignment
    2Follow the instructions in the wizard and perform the appropriate steps
    Screenshot from R/L alignment, TPS 320i - 600i

    NOTE!

    The inductance in the welding circuit varies with the measuring position.

    When the position is changed, the effective area of the welding circuit changes and, as a result, the inductance changes. The conditions for droplet detachment are not constant.

    The power source calculates an instantaneous value of inductance for the pulse, PMC, and CMT welding processes, and the process controllers can better respond to inductance changes.

    Position 1:

    Position 2:

    Different inductance area and welding circuit resistances according to position on longitudinal chassis

    IMPORTANT!
    Compare the R/L alignment at the front and rear ends of a welding position!
    This allows you to assess whether optimization measures are necessary.

    1. General information about the welding circuit
    2. Inductance in the welding circuit

    Standard values for possible process interference

    Standard values of welding circuit resistance R and inductance L for possible process interference:

    Welding process

    R [mOhm]

    L [μH]

    Conventional dip transfer arc *
    LSC *
    LSC ADV. *
    CMT *

    ≤ 50
    ≤ 50
    ≤ 50
    ≤ 50

    ≤ 30
    ≤ 20
    ≤ 60
    ≤ 40

    Pulsed arc *

    ≤ 25

    ≤ 40

    Spray arc **

    ≤ 60

    ≤ 80

    Assumptions:

    *
    Welding current 120 A, filler metal ø 1.2 mm, shielding gas M21
    **
    Spray arc with 300 A, filler metal ø 1.2 mm, shielding gas M21

    NOTE!

    Depending on the power source type, operating point, characteristic property, and interference, the recommendation may differ.

    Spray arc
    The spray arc is most insensitive to high currents due to its almost constant current flow.

    Conventional dip transfer arc
    The short-circuit behavior is event-oriented.

    LSC (Low Spatter Control)
    With its prediction-oriented dip transfer arc strategy, LSC is sensitive to high inductances.
    The disruption of the inductive decay behavior is significantly improved with the aid of an electronic switch in the welding circuit (e.g., hardware, TPS 400i LSC ADV).

    CMT
    Due to the cyclic process adjustment with each forward and backward movement of the wire electrode, CMT is between LSC and LSC ADV.

    Pulsed arc
    Pulsed arc variants are the most sensitive because high pulsed currents require low resistances and low inductances.
    Adjusted PMC multi-arc characteristics with reduced rates of change and reduced current levels can be used as a remedy.

    1. General information about the welding circuit

    Magnetic interference of the arc

    Magnetic arc blow

    If an electrical conductor is in a magnetic field, a resultant force acts on it.
    This is known as the Lorentz force and it depends on the current direction, magnetic field direction, and their orientation to each other.

    Even the smallest magnetic force effects generate a geometric deflection of the arc.
    This undesirable interaction is referred to as "magnetic arc blow".

    MIG/MAG weldability depending on magnetic flux density:

    Very good

    Good

    Average

    Poor

    Impossible

    ≤ 2 mT

    2-4 mT

    4-6 mT

    6-8 mT

    ≥ 8 mT

    ≤ 20 Gauss

    20-40 Gauss

    40-60 Gauss

    60-80 Gauss

    ≥ 80 Gauss

    General measures against arc blow:
    • Use multiple tacking points
    • Shorten the distance between the contact tip and workpiece
    • Increase welding current (= increase arc pressure)
    • Use run-off plates
    • Demagnetization (see also from page (→))

    Magnetized components can deflect an arc and interfere with droplet detachment.
    The current-carrying wire electrode and the arc plasma also generate concentric magnetic fields, which are distorted at component ends and uneven air gaps and also exert a deflecting force on an arc.
    Current-carrying parts of a clamping device retain a residual magnetism (= remanence) if they are made of a ferritic material. Aluminum, copper, and austenitic steels do not retain remanence.

    Force effect on the arc due to magnetic fields:

    I = Welding current [A]
    B = Magnetic flux [mT]
    F = Deflection force [N]
    F = Deflection force [N]

    The strength of the magnetic field in the component depends on the current level, the magnetic conductivity (material), the cross-section, and the number and size of the air gaps in the magnetic circuit.
    Welding over the premagnetized current path can have a negative effect on stability.

    Arc blow away from the ground connection:

    The position of the earthing clamp is crucial for the current flow direction and its magnetic field in the component.
    The electric current always chooses the shortest distance, with the same materials and cross-sections, and determines the arc deflection direction opposite to the earthing clamp.

    NOTE!

    Determination of the force effect on the arc:

    by means of the right-hand rule

    Thumb in welding current direction

    Index finger in the direction of the magnetic field lines

    Middle finger points in force direction

    1. General information about the welding circuit
    2. Magnetic interference of the arc

    Magnetic arc blow

    If an electrical conductor is in a magnetic field, a resultant force acts on it.
    This is known as the Lorentz force and it depends on the current direction, magnetic field direction, and their orientation to each other.

    Even the smallest magnetic force effects generate a geometric deflection of the arc.
    This undesirable interaction is referred to as "magnetic arc blow".

    MIG/MAG weldability depending on magnetic flux density:

    Very good

    Good

    Average

    Poor

    Impossible

    ≤ 2 mT

    2-4 mT

    4-6 mT

    6-8 mT

    ≥ 8 mT

    ≤ 20 Gauss

    20-40 Gauss

    40-60 Gauss

    60-80 Gauss

    ≥ 80 Gauss

    General measures against arc blow:
    • Use multiple tacking points
    • Shorten the distance between the contact tip and workpiece
    • Increase welding current (= increase arc pressure)
    • Use run-off plates
    • Demagnetization (see also from page (→))

    Magnetized components can deflect an arc and interfere with droplet detachment.
    The current-carrying wire electrode and the arc plasma also generate concentric magnetic fields, which are distorted at component ends and uneven air gaps and also exert a deflecting force on an arc.
    Current-carrying parts of a clamping device retain a residual magnetism (= remanence) if they are made of a ferritic material. Aluminum, copper, and austenitic steels do not retain remanence.

    Force effect on the arc due to magnetic fields:

    I = Welding current [A]
    B = Magnetic flux [mT]
    F = Deflection force [N]
    F = Deflection force [N]

    The strength of the magnetic field in the component depends on the current level, the magnetic conductivity (material), the cross-section, and the number and size of the air gaps in the magnetic circuit.
    Welding over the premagnetized current path can have a negative effect on stability.

    Arc blow away from the ground connection:

    The position of the earthing clamp is crucial for the current flow direction and its magnetic field in the component.
    The electric current always chooses the shortest distance, with the same materials and cross-sections, and determines the arc deflection direction opposite to the earthing clamp.

    NOTE!

    Determination of the force effect on the arc:

    by means of the right-hand rule

    Thumb in welding current direction

    Index finger in the direction of the magnetic field lines

    Middle finger points in force direction

    1. General information about the welding circuit
    2. Magnetic interference of the arc

    Magnetic arc blow during TWIN welding

    Two adjacent arcs with the same current direction attract each other.
    The smaller the angle and the shorter the distance between the wire electrodes, the greater the mutual attraction.

    Arc blow during TWIN welding
    I1
    Welding current of leading electrode
    I2
    Welding current of trailing electrode
    B1
    Magnetic flux due to the leading electrode
    B2
    Magnetic flux due to the trailing electrode
    F1
    Deflection force due to the leading electrode
    F2
    Deflection force due to the trailing electrode

    An arc in the pulsed phase exerts a strong magnetic field on the second arc.
    Welding away from ground is advantageous because both arcs are forced forward.

    NOTE!

    Synchronized characteristics with high plasma pressure at high amperage have been developed for TWIN welding.

    1. General information about the welding circuit
    2. Magnetic interference of the arc

    Demagnetizing with alternating voltage

    Demagnetizing components reduces the arc blow and is achieved by means of cyclic remagnetization. Lifting magnets or demagnetizing devices can be used for cyclic remagnetization.
    Applications include in pipeline construction or for components with production- or transport-related residual magnetism.

    Simple alternative if the lifting magnet has no demagnetizing function:
    Use of a TIG AC power source (e.g., iWave AC/DC) + short-circuited grounding cables on the wrapped component while reducing the current amplitude.

    Demagnetizing with iWave AC/DC:

    Demagnetizing with AC alternating field
    Parameterization and measures for a decaying current curve:
    1. Current offset = +10
    2. AC half-wave waveform:
      Positive half-wave = sine
      Negative half-wave = sine
    3. Main parameters:
      DownSlope > 10.0 s
      Final current = 3 A (= minimum)
      Main current = approx. 300 A
    4. Wrap welding power-lead around the component at least 3 times
    5. Press torch trigger in 2-step mode
    1. General information about the welding circuit

    Interference coupling

    Interference coupling

    If several arcs are being used to weld one component or in one welding cell, the routing of the hosepacks and grounding cables is a decisive factor in their mutual interference.

    The following figure shows two parallel grounding cables.
    The red cable (a) has current flowing through it and induces a voltage in the gray cable (b).
    The magnitude of the induced voltage is described by the coupling factor (M).

    Decaying coupling factor due to distance

    The coupling factor is inversely proportional to the distance (d). The greater the distance, the lower the induced voltage.

    A minimum distance of 30 cm is recommended.

    NOTE!

    Routing the return lead cables together in a ferritic channel (e.g., iron rail) strengthens the coupling.

    Avoid routing the return lead cables together in a ferritic channel!

    1. General information about the welding circuit
    2. Interference coupling

    Interference coupling

    If several arcs are being used to weld one component or in one welding cell, the routing of the hosepacks and grounding cables is a decisive factor in their mutual interference.

    The following figure shows two parallel grounding cables.
    The red cable (a) has current flowing through it and induces a voltage in the gray cable (b).
    The magnitude of the induced voltage is described by the coupling factor (M).

    Decaying coupling factor due to distance

    The coupling factor is inversely proportional to the distance (d). The greater the distance, the lower the induced voltage.

    A minimum distance of 30 cm is recommended.

    NOTE!

    Routing the return lead cables together in a ferritic channel (e.g., iron rail) strengthens the coupling.

    Avoid routing the return lead cables together in a ferritic channel!

    1. General information about the welding circuit
    2. Interference coupling

    Example: Coupling of two welding circuits in the pulsed arc

    Disruption of voltage flow U2 due to induced voltages of a second circuit
    I1
    Target welding current power source 1
    I2
    Target welding current power source 2
    U1
    Required voltage welding circuit 1
    U2
    Required voltage welding circuit 2
    Uc
    Coupling voltage

    The figure shows the idealized current waveforms (I) in red and the idealized voltage waveforms (U) in blue of two power sources.
    Power source 1 induces a coupling voltage (Uc) into the welding circuit of power source 2 during welding.

    This coupling voltage adds to or subtracts from the arc voltage and distorts the actual ratios of arc length and droplet detachment and their measured values for the second power source.
    As a result of this interference, a cyclic change in arc length occurs.

    The figure also shows a typical setup with parallel hosepacks and return lead cables, which couple mutually induced voltages. Separating the welding circuits or having a sufficient distance between the current-carrying conductors does away with this magnetic coupling (see also page (→)).

    NOTE!

    Simplest way to check coupling in the event of welding process instabilities:

    Weld with only one arc at a time on the component and compare the welding result.

    Uneven seam progression with interference voltage coupling into the welding circuit:

    Arc length interference due to induced voltages of a second circuit
    Series A: Welding result with coupled arc length interference
    Series B: Welding result taking into account remedial measures

    The arc changes that lead to this undesirable welding result are visible in the high-speed image and also to the naked eye.

    Remedial measures as described in the optimization examples starting on page (→) reduce the arc length disruption.
    A good welding result with a stable arc length is achieved.

     

    1. General information about the welding circuit
    2. Interference coupling

    Measuring the coupling factor

    TPSi power sources can measure the coupling of one or more welding circuits:
    • The ohmic part shows the resistance value of a common grounding cable
    • The percentage corresponds to the inductive coupling

    Start welding circuit coupling:

    1On the power source, select:
    Process parameters / Components & Monitoring / Welding circuit coupling
    2Follow the instructions in the wizard and perform the appropriate steps

    IMPORTANT! The work steps must be performed on both power sources!

    Result of the coupling measurement in mOhm (R_coupling) and % (k_coupling)

    0 mOhm / 0%
    Two completely separate welding circuits

    High mOhm value
    A great deal of static coupling, e.g., through shared grounding cables

    High % value
    A great deal of dynamic coupling, e.g., due to closely positioned, parallel hosepacks or return lead cables of external power sources
    If two return lead cables or hosepacks are routed or wound together in one ferritic rail, this increases the mutual interference and thus the dynamic coupling.

    The evaluation of the measurement results is divided into four ranges. If the measurement results fall within the lower two ranges, the welding circuits on one component should be optimized.

    1. General information about the welding circuit
    2. Interference coupling

    Couplings with multiple arcs on one component

    If several arcs are being used to weld one component, the coupling values of the individual welding circuits in relation to each other should be determined. The individual coupling values add up when all arcs magnetically influence each other.

    Recording the individual current paths and measuring, analyzing, and modifying them in pairs simplifies optimization of the welding circuits.

    Adding the coupled magnetic interference using the example of 4 arcs on one component

    How to perform a coupling measurement:

    1Start the welding circuit coupling on 2 power sources (see page (→))

    The two power sources synchronize during the alignment via the short circuit currents and measure each other reciprocally.
    2Document the measurement results
    3Repeat the coupling measurement with other power source pairs
    4Compare the measurement results

    Structure of the welding circuit

    Grounding point design

    General

    To achieve reproducible welding results, the electric welding circuit must be planned and optimized if necessary.
    In addition to the position and length of the return lead cables, their attachment is also crucial to achieving welding results of consistent quality.

    1. Structure of the welding circuit

    Grounding point design

    General

    To achieve reproducible welding results, the electric welding circuit must be planned and optimized if necessary.
    In addition to the position and length of the return lead cables, their attachment is also crucial to achieving welding results of consistent quality.

    1. Structure of the welding circuit
    2. Grounding point design

    General

    To achieve reproducible welding results, the electric welding circuit must be planned and optimized if necessary.
    In addition to the position and length of the return lead cables, their attachment is also crucial to achieving welding results of consistent quality.

    1. Structure of the welding circuit
    2. Grounding point design

    Contact force/surface pressure

    A high contact force or surface pressure is required to ensure low contact resistances:

    • Avoid ground connections spread over a large area
    • Provide one or more point-shaped current application points

    Screw terminals have the highest contact forces (> 1000 N).

    Frequently used clamping elements and toggle clamps are usually not precisely defined, especially with regard to tolerances.

    Grounding points – rigid variants

    The figure shows point-shaped grounding point variants.
    The pneumatic version with two grounding points has additional spring-loaded clamping cylinders for different forces and diameters.

    Grounding points – rail systems

    The second figure shows sliding grounding contact variants, used on or in rail systems.
    A high surface pressure is also of great importance for these systems. Therefore, it must be ensured that the sliding block cannot lift off.
    In many cases, a circuit is designed with two spring-loaded sliding blocks to stop this happening.
    Dirt deflectors or wiper systems keep the rail free of dust and insulating grease.

    1. Structure of the welding circuit
    2. Grounding point design

    Separate grounding points

    Each welding circuit requires its own grounding point or grounding rail, which must be sufficiently dimensioned.

    IMPORTANT!

    • A clean surface is a prerequisite.
    • Clean oxidized grounding contacts.
    1. Structure of the welding circuit
    2. Grounding point design

    Grounding contacts for rotating devices

    There are variants with sliding grounding contacts for rotating devices and components:

    Grounding points – rotating components

    Important features of grounding contacts for rotating devices:

    • Sufficient contact force
    • A separate grounding contact for each welding circuit
    • Grounding greases with copper or graphite fillers are not recommended!
      (Can be used as an alternative if sufficient contact force cannot be achieved)
    1. Structure of the welding circuit
    2. Grounding point design

    Number of grounding points

    Planning multiple grounding points can significantly reduce the length of the current paths and inductance areas. Shared grounding cables are avoided and current paths are separated.
    To obtain approximately equal resistance values, return lead cables should be of equal length and run parallel to the welding positive hosepack for as long as possible.

    Grounding points – net-shaped routing on the hall floor

    The figure shows the grounding cables routed in a net shape on the hall floor.
    Large longitudinal chassis would have very high resistances and inductances with long drag chains for the hosepack and return lead cable.

    • The power source is mobile and positioned on the boom (a).
    • The carriage of the boom travels on rails (b) in the hall

      Aim:
      To weld the longitudinal seams of the beam (f).
    • The sliding grounding contact (e) on the grounding rail (c) always guarantees a welding circuit (d) with a small area and low resistances and inductances.
    1. Structure of the welding circuit

    Notes on welding circuits in manual welding systems

    Compact welding systems

    In the case of compact welding systems with an integrated wire drive and without an interconnecting hosepack, short torch hosepacks are usually also used.
    Here, the routing of the return lead cable in particular must be taken into account:

    • Keep the return lead cable as short as possible
    • Lay the return lead cable without coils

    This results in:

    • Low inductances < 10 μH
    • Low resistances < 15 mOhm
    • No interfering influencing factors – all desired process current changes can be realized

    NOTE!

    Poorly clamped ground connections or dirty workpiece surfaces have large, changing contact resistances.

    1. Structure of the welding circuit
    2. Notes on welding circuits in manual welding systems

    Compact welding systems

    In the case of compact welding systems with an integrated wire drive and without an interconnecting hosepack, short torch hosepacks are usually also used.
    Here, the routing of the return lead cable in particular must be taken into account:

    • Keep the return lead cable as short as possible
    • Lay the return lead cable without coils

    This results in:

    • Low inductances < 10 μH
    • Low resistances < 15 mOhm
    • No interfering influencing factors – all desired process current changes can be realized

    NOTE!

    Poorly clamped ground connections or dirty workpiece surfaces have large, changing contact resistances.

    1. Structure of the welding circuit
    2. Notes on welding circuits in manual welding systems

    Split welding systems

    In split welding systems, a separate wirefeeder is connected to the power source via an interconnecting hosepack.
    The length of the interconnecting hosepack and its arrangement are decisive factors in the inductance in the welding circuit.

    Winding the interconnecting hosepack on the trolley or, in the worst case, around the gas cylinder multiplies the total inductance in the welding circuit.

    Remedy
    Wind return lead cables and interconnecting hosepacks in opposite directions:

    Opposite winding of interconnecting hosepacks and grounding cables

    The figure shows how the interconnecting hosepack is picked up in the middle and then wound up.

    Compensated interconnecting hosepacks

    With compensated interconnecting hosepacks, the welding positive lead and return lead cable are routed in one hosepack.

    Compensated interconnecting hosepack with both polarities in one hosepack, between power source and wirefeeder

    Almost the entire magnetic field is compensated for by means of an internal "4-strand arrangement".

    In shipbuilding and pipeline construction in particular, this special solution can be a variant for short return lead cables and low inductances.

    1. Structure of the welding circuit

    Notes on welding circuits in automated welding systems

    General

    Especially in automated systems or robot applications, the welding circuit must be planned first in order to exclude or reduce process interference in advance.
    Subsequent planning and also optimization can often only be implemented at great expense.

    The system design should use the same return lead cable lengths and cross-sections for the different grounding points.
    The effective area between the hosepack and the grounding cable determines the inductance and should be kept as small as possible.

    Component or device should be isolated from ground potential to avoid parallel ground currents and voltage potential shifts.

    1. Structure of the welding circuit
    2. Notes on welding circuits in automated welding systems

    General

    Especially in automated systems or robot applications, the welding circuit must be planned first in order to exclude or reduce process interference in advance.
    Subsequent planning and also optimization can often only be implemented at great expense.

    The system design should use the same return lead cable lengths and cross-sections for the different grounding points.
    The effective area between the hosepack and the grounding cable determines the inductance and should be kept as small as possible.

    Component or device should be isolated from ground potential to avoid parallel ground currents and voltage potential shifts.

    1. Structure of the welding circuit
    2. Notes on welding circuits in automated welding systems

    Example

    Systems with one grounding point

    Example – rotating unit with longitudinal chassis

    • One grounding point at the end of the component
    • Very long current path
    • Large area between welding positive and ground results in undesirably large inductance
    • Welding is carried out towards ground, which results in magnetization of the component
    Longitudinal chassis with one grounding point

    Remedy:
    Setup with multiple grounding points

    Longitudinal chassis with two grounding points

    The second figure shows the longitudinal chassis with an additional grounding contact.
    The areas between the welding positive lead and the return lead cable across the component become significantly smaller and also more constant over the travel path.

    1. Structure of the welding circuit
    2. Notes on welding circuits in automated welding systems

    Further information

    • When changing the current path, the different force effect on an arc may require the "away from ground" welding direction in the application.
    • For components with an air gap, provide both halves with a grounding point to avoid magnetic flux across the welding gap.
    • Run the welding positive lead and grounding cable in parallel for as long as possible to achieve mutual compensation.
    • Use equal return lead cable lengths and arrange them in an optimized way.
    • Maintain a sufficient distance from the machine bed or ferritic materials.
    1. Structure of the welding circuit

    Welding with multiple arcs on one component

    General

    Both manual and automated processes can use multiple arcs on a single component, which can lead to magnetic coupling effects.

    1. Structure of the welding circuit
    2. Welding with multiple arcs on one component

    General

    Both manual and automated processes can use multiple arcs on a single component, which can lead to magnetic coupling effects.

    1. Structure of the welding circuit
    2. Welding with multiple arcs on one component

    Separating welding circuits

    If several arcs are being used to weld one component simultaneously, all welding circuits must be separated from each other:

    • Avoid shared grounding points
    • Avoid return lead cables and hosepacks routed in parallel
    • Route current paths of different machines separately
    • Do not run current paths under another arc
    Possible errors in the cable layout and how to optimize them
    A
    Welding system with setup errors (a)
    Crossing current paths
    Shared ground potential
    Current path routed under the second arc (b)
    B
    Correctly set up welding system – power and return lead cables compensate each other (d)
    Separated grounds and non-overlapping current paths (e)

    Result of optimization:

    • Small inductance areas (f) in contrast to large areas (c)
    • Coupling values (A): 15 mOhm / 60%
      Coupling values (B): 0 mOhm / 0%
    1. Structure of the welding circuit
    2. Welding with multiple arcs on one component

    Sensor cable for correct voltage measurement

    Interference voltages from neighboring welding circuits influence the arc length control and lead to instabilities in the welding process (see also from page (→)).

    Remedy:
    Direct voltage measurement by means of sensor cable (c) from component to the next system bus interface (e.g., wirefeeder (b), SplitBox, or SB 60i)

    From this interface, the voltage potential is transmitted to the power source without interference.

    Sensor cable from component to wirefeeder
    (a)
    Power source
    (b)
    Wirefeeder, SplitBox, or SB 60i
    (c)
    Sensor cable
    (d)
    Distance, min. 30 cm
    (e)
    SpeedNet bus communication

    The figure shows the circuit diagram of the sensor interfaces (a) and (b).
    The sensor cable is routed separately from the SpeedNet bus communication (e) but in the same multipole robot cable in the hosepack.

    The physical effects of resistance and inductance due to the welding circuit arrangement do not change, since these are determined by the current-carrying cables (hosepack and return lead cable).
    The measurement of the arc voltage is improved, and interferences in the voltage measurement are eliminated.

    IMPORTANT!
    Improving the hosepack arrangement is always the first optimization choice.

    The distance (d) from the sensor cable to the return lead cable or hosepack should be at least 30 cm, if possible, to avoid coupled voltages in the sensor cable.

    Single-wire welding systems usually do not require a sensor cable.

    1. Structure of the welding circuit
    2. Welding with multiple arcs on one component

    Sensor cable for multiple arcs

    If several arcs are being used to weld one component, the sensor cable brings a significant improvement in the voltage measurement and thus the arc stability, if the hosepack and ground wiring has not been optimally designed.

    Example: Rotary table with the welding area behind a partition wall

    Sensor cable from component to wirefeeder for improved voltage measurement, when hosepack and ground wiring are not designed optimally
    • Two robots weld simultaneously on one component, (e) = partition wall
    • Unfavorable arrangement of return lead cables (-) 1 / (-) 2 and hosepacks (+) 1 / (+) 2
    • The welding circuit of power source 1 couples an induced voltage into the welding circuit of power source 2 – correct measurement of the arc voltage is not possible.
    • One sensor cable (c) per welding circuit at a sufficient distance (d) from the current-carrying cables transmits the arc voltage to the wirefeeder without interference, and from there, shielded to the power source.

    Multiple welding positions require multiple grounding contacts and sensor cables on the device. These must also be arranged with sufficient spacing to avoid coupling.

    Several sensor cables can be routed together in one cable harness, since they do not carry welding current and do not cause mutual coupling.

    With long welding gantries, a sensor cable does not bring any advantages. Therefore, short welding circuit lengths should be planned when designing the system.

    NOTE!

    The sensor cable can be used as a retrofit solution, e.g., for existing systems.

    Ideally, the expected current flow is already taken into account during system planning.

    Optimization examples

    Optimization examples

    Overview

    The following optimization examples are described in the next sections:

    • Several individual welding systems on one component
    • TWIN welding system
      TWIN welding systems are multi-wire welding systems that are isolated from each other and have at least two consumable electrodes in a shared weld pool.
    • Multiple TWIN welding systems on one component
      Two or more TWIN systems on one component multiply the risk of mutual interference.
    1. Optimization examples

    Optimization examples

    Overview

    The following optimization examples are described in the next sections:

    • Several individual welding systems on one component
    • TWIN welding system
      TWIN welding systems are multi-wire welding systems that are isolated from each other and have at least two consumable electrodes in a shared weld pool.
    • Multiple TWIN welding systems on one component
      Two or more TWIN systems on one component multiply the risk of mutual interference.
    1. Optimization examples
    2. Optimization examples

    Overview

    The following optimization examples are described in the next sections:

    • Several individual welding systems on one component
    • TWIN welding system
      TWIN welding systems are multi-wire welding systems that are isolated from each other and have at least two consumable electrodes in a shared weld pool.
    • Multiple TWIN welding systems on one component
      Two or more TWIN systems on one component multiply the risk of mutual interference.
    1. Optimization examples
    2. Optimization examples

    Multiple individual welding systems on one component – before optimization

    Multiple individual welding systems on one component – before optimization
    • Parallel grounds and parallel hosepacks reciprocally couple interference into the welding circuits.
    • Shared ground nodes or grounding rails mean 100% coupling of one circuit into the other.
    • The figure shows transposed return lead cables in the upper sketch, resulting in crossing current paths in the component.
    • When using a ground node, the current path changes from power source 2 via grounding point 1 (shown in the figure in the lower sketch) due to the shorter path or lower resistance.
    1. Optimization examples
    2. Optimization examples

    Multiple individual welding systems on one component – after optimization

    Multiple individual welding systems on one component – after optimization
    • Two separated welding circuits that do not affect each other and have no shared grounding points.
    • The danger of current paths crossing in the workpiece in a known working area is avoided after circuit planning.
    • The inductance areas are significantly reduced, which makes it easier to regulate the target current ramps and thus ensures stable weld droplet detachment.

    The images from before and after optimization are shown in an enlarged view underneath.

    Multiple individual welding systems on one component – before optimization

    Multiple individual welding systems on one component – after optimization

    1. Optimization examples
    2. Optimization examples

    TWIN welding system – before optimization

    TWIN setup before optimization
    • Both power sources stand together on a podium.
    • Return lead cables as well as robot hose packs are arranged in parallel.
    • Both return lead cables are arranged in a shared steel tray.
    • Hosepacks positioned close to one another on the robot.
    • Large effective inductance areas.
    1. Optimization examples
    2. Optimization examples

    TWIN welding system – after optimization

    TWIN setup after optimization
    • Both circuits are separated from each other.
    • In the TWIN welding circuits, the welding positive lead and return lead cables are each routed as parallel as possible to keep the inductance areas low.
    • The hosepacks are separated and routed in drag chains with the greatest possible distance between them.
    • Both return lead cables are routed in separate channels and ideally fastened or clamped directly to the component.
      ==>
      Two recommended variants:
      a) For components with a gap, divide the return lead cables between both halves (lower sketch).
      b) Arrange the earthing clamps so that welding is carried out away from ground (upper sketch).

    The images from before and after optimization are shown in an enlarged view underneath.

    TWIN setup before optimization

    TWIN setup after optimization

    1. Optimization examples
    2. Optimization examples

    Multiple TWIN welding systems on one component – before optimization

    Multi-TWIN system before optimization
    • The concentration of all power sources in one place results in an unfavorable routing of hosepacks and grounding cables together.
    • The parallel arrangement of the hosepacks without sufficient spacing or running them all along steel girders and trays together increase the mutual interference.
    1. Optimization examples
    2. Optimization examples

    Multiple TWIN welding systems on one component – after optimization

    Multi-TWIN system after optimization
    • Separation of the TWIN welding systems with their own welding circuits.
    • Long parallel routing of the hosepack and the associated return lead cable – the inductive effective area is reduced and at the same time the magnetic field in this section is compensated.
    • As soon as the TWIN hosepack splits into two individual hosepacks at the Y-junction, lay the two individual hosepacks as far apart from one another as possible (min. 30 cm).
    • Two separate drag chains or sufficient spacing (min. 30 cm).

    The images from before and after optimization are shown in an enlarged view underneath.

    Multi-TWIN system before optimization

    Multi-TWIN system after optimization