Load Bank Test; Test Welding - Kemppi Minarc Evo 150 Service Manual

Service manual Minarc Evo 150 and 180

4.5.1. Load bank test

CC (MMA and TIG machines) curve's secondary voltage can be calculated when a certain current is set:
 I 
U , 0
MMA mode:
2 2
 I 
U , 0 04
TIG mode:
2 2
Voltage has to be set for the nominal curve to get the correct output power. E.g. when making a PTC test
the correct values must be used to meet the duty cycle specified in technical specification.
Most useful tests to be made with a load bank are to check maximum and minimum current and panel
display values.
The following example uses 140A so the correct voltage can be calculated using the equation below:

I 140 A
2
  
U I , 0 04 20
2 2
   
140 A , 0 04 20 25
Output voltage should be 25,6V.
Example: Minarc Evo 150 MMA mode load bank test, welding current 140A and output voltage 25,6V

Turn the machines main switch OFF

Connect machine to the load bank and check that there is no load added.

Turn the machines main switch ON,

Adjust machine current to desired level (this example uses 140A)

Add some load to get the inverter operate, be fast in switching because arcing may exist
between the connection surfaces of the switch

Measure load voltage by a DMM

Add or decrease load to get the desired voltage
If using active load bank, instead of increasing or decreasing load, it is only necessary to select MMA
nominal curve and then set the test current value on the machine. The Load follows automatically the
current value and the output voltage will be correct.

4.5.2. Test welding

Test welding is important for having final and reliable information, if the maintenance / repair has been
made successfully.
In some cases a load bank test alone does not give the absolute truth if the machine is functioning
properly or not. Test welding will show if the power source and control panel are working together in a
natural state.
While carrying out test welding, it is useful to test at different current settings to see if the current is right
and ignition good.
Pay attention especially to the features that were the original reason for the maintenance work.
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Kemppi Oy

04 20
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10
6 , V
Version 1.3 30.9.2015