TROUBLESHOOTING OF XIM POWER SOURCES
FAULT FINDING PROCEDURE
If the power source is not working or if the power source is not working in proper way and you dont know why follow the next procedure:(If you have some prior experience you can skip some of following steps)
1§ Check the incoming line voltage between lines.Proper operation needs 380V+-10% but the machine can operate witg reduced performance in voltage range 300V to 450V between lines. The Machine has under and overvoltage shutdown to protect the machine from failure.You have to follow thw input ac voltage down to primary rectifier because there may be some breaks inside the power source.
2§ Check the dc-link voltage over dc-link capacitors.The link voltage must be 535V+-10V at rated input voltage (380Vac) when the machine is in no load condition.The link voltage drops with increasing load down to 500V at rated load of500A.If the dc-link voltage is good in no-load condition but drops heavily when loading the machine it means that one input line is missing or primary rectifier is broken.
3§ If there is no output when started or if the inteface panel is not working (nothing to see in lcd-panel) check auxiliary voltages on control card.There are four different dc-voltages on control card:
42V dc non-regulated test point at kathode of V65-V66
24V dc regulated test poin at kathode of V72
17V dc regulated test point pin 10/X3 or at N5
3,3V dc regulated test point pin 11/X3 or over C5
The nonregulated 42V voltage varies with load and line voltage but normal operation is possible if the 42V does not vary not more than 15% of nominal.The regulated voltages MUST be within +- 5% of nominal.
If all aux. voltages are zero check the fuse and auxiliary transformer
4§ If the machine do not start when started on pistol trigger (and if dc-link voltage and aux.voltages are ok) make following checks:
a) check the outgoing square-wawe voltage in wire-feeder interface on control card. Thre must be square-wave between pins pin 4/X5 and 5/X5.The positive and negative amplitudes depends on potentiometer settings in wire feeder.
b) check voltage and wire-feed set values on pins 18/X3 (voltge set value) and 17/X3 (wire feed speed set value) ( if it is difficult to measure on connector X3 the other alternative is to measure on pcb board on capasitors C54 voltage set value and C80 wire feed spees set value) on control-card.Correct values are: 0 to 3,5V for votage set value and 0 to 2,7 V for wire feed speed set value.
c) check the start-command on control card on pin 12/X3 (or on R64 on pcb board)
5§ If the machine do not start after checks of previous paragraphs make folowing checks:
a) measure IGBT-gate cotrol pulses first on control card on pins 6/X4 and 7/X4 preferably with oscilloscope or if osciloscope is not available with universal instrument in ac-voltage range.The voltage must be something between 2V and 16Vac.
b) measure the gate-control pulses on primary card Z001 on the primary pins of gate-control transformer.The measurement should be made preferably with oscilloscope by using differential voltage probe.If oscilloscope is not available measurement can be made with universal instrument in ac-voltage range.The voltage should be something between 2Vac and 16Vac.
6§ If the previous checks are ok but the machine do not work check that the inrush current suppression relay is energised (voltage over relay coil over 20V).This relay is on primary card.
7§ If previous cheks are ok but the machine do not work measure voltage over the primary of main transformer.THIS MEASUREMENT MUST BE MADE BY USING OSCILLOSCOPE WITH DIFFERENTIAL VOLTAGE PROBE!!!!!
8§ Next measure the voltage with oscilloscope on the secondary of the main transformer
FIG 1. Essential testing points
SOME ADDITIONAL TESTS
A. DC-link voltage
By measuring dc-link voltage it is possible to find breaks in primary circuitry.In fig 2 there is normal link voltage and in fig 3 there is break in one phase line
FIG 2 .Correct DC-link voltage
Fig 3. DC-link voltage one phase missing.
In this fig 4 there is voltage over low-side igbt.In normal case there is no significant oveshoot. Some ringing after igbt turn-off is normal
C. Voltage over secondary diodes
FIG 5. Voltage over secondary diode in normal operation
D. Main transformer test
Fast check for main transformer is :
1) primary inductance measurement when secondary is open.Corect value 0,8..0,9 mH for500A XIM and 0,95..1,05 mH for350A machine.
2) Primary inductance when extreme ends of transformer seconcary are in short-circuit.CENTER TAP BUSBARS MUST BE TOGETHER BUTNOTCONNECTED TO REAR ENDS OF SECONDARY.Correct value less than 10uH.