Why Go MFDC

Improved and consistent power factor

  • Inductive impedance is eliminated since the diodes on the secondary of the welding transformer provides Direct Current to the weld instead of Alternating Current.

  • Power mains are not distorted since there is no induction.

  • There is no need to purchase expensive Power Factor correction systems for the plant if all welding is done with MFDC inverters.

  • Capacitors in the inverters improves the mains.

Automatic Load Distribution

 

MFDC Loads are evenly distributed over the three phase.

The bank of capacitors that are found on the MFDC system allows for current to draw from the bank as well as from the line thus reducing peak line currents.

 

 

Significant Cost Savings

MFDC Inverter will do more welding with less energy
   

 

MFDC

AC Robot Gun

AC Gun Cable

Electricity cost per kw hour 

£0.06

£0.06

£0.06

Secondary Current 

12000

12000

12000

Turn Ratio 

74

50

15

Welding Cycles 

12

12

12

Power Factor 

99%

85%

95%

Primary Voltage 

415

415

415

 

 

 

 

Cost per weld 

£0.000211

£0.000282

£0.000999

 

Welds per part control 

25

25

25

Parts per hour 

50

50

50

Hours per day 

16

16

16

Days per week 

5

5

5

Weeks per year 

46

46

46

 

Parts per year 

184,000

184,000

184,000

 

Welds per year by control 

4,600,000

4,600,000

4,600,000

 

Electricity cost foe weld per year  

£970.49

£1,298.12

£4.594,33
   

Eliminates the need and maintenance of expensive Kick less cables

Due to higher operating frequencies (400 to 2000Hz),
the welding transformer can be as much as 74% smaller than the traditional AC weld transformer (50 / 60 Hz). 

This allows the user to locate the transformer much closer to the welding gun thus eliminating the use of expensive Kick less cables that need to be maintained and monitored.

Precise welding current

Most precise current control is achieved with MFDC inverters.

MFDC utilizes IGBT's for switching.  These are turned on and off at the rate of 400 to 2000 times per second. 

By controlling both the turn on and turn off, the MFDC can use a deterministic approach to controlling weld current. 

Conventional AC controls utilize SCR's for switching.  These are turned on by the weld control but then remain conducting until the line voltage crosses the zero point during the base frequency line cycle. 

Because of this, conventional AC controls must use a predictive algorithm rather than a deterministic approach.  Also, if an under or over compensation occurs on one of the cycles, the AC control will have to wait until the next period of the base frequency whereas the MFDC need only wait a fraction (1/20th nominal) of that time.

Welding process friendly

MFDC eliminates undesired inter-cycle cooling periods that exist in AC resistance welding processes.  Welding therefore can occur faster which would then reduce heat waste and the problems associated to eliminating that waste.

Welding current time can also be decreased since there is no inter-cycle cooling periods.  This additional benefit would contribute to more energy savings, better production cycle times, reduced wear on welding apparatus, and more…

Flexible welding systems

AC systems need to be sized correctly so that control of welding current is achieved in the area of 70 to 90 percent of maximum current. 

This means for example that a 20K amp welder is suited for welding applications ranging from 14K amps to 18K amps.  Although it is possible to use this welder for applications requiring much less than 14K amps, it does mean working in areas of instability. 

MFDC systems can work from 20 to 90 percent of maximum hence in a similar 20K amp MFDC welder can be used reliably from 4K amps to 18K amps.