ESAB Plasmarc EPP-450 - Page 52

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SECTION 6 TROUBLESHOOTING
REPLACEMENT:
A. Thoroughlycleananythermalcompoundfromtheheatsinkandthemodules.Anyforeignmaterialtrappedbetween
themoduleandheatsink,otherthananappropriatethermalinterface,cancausemoduledamageduetooverheat-
ing.
B. Inspectthethermal(interface)pad,P/N951833,fordamage.Acreaseordeformitycanpreventthemodulefromseat-
ingproperly,impedingtheheattransferfromthemoduletotheheatsink.Theresultcanbemoduledamagedueto
overheating.
Ifathermalpadisnotavailable,aheatsinkcompoundsuchasDowCorning®340HeatSinkCompoundmaybeused.It’s
agoodideatomountallparalleledmoduleslocatedonthesameheatsinkusingthesamethermalinterface.Dierent
interfacescancausethemodulestooperateatdierenttemperaturesresultinginun-equalcurrentsharing.Theimbal-
ancecanshortenmodulelife.
C. Placeathermalpad,andanIGBTmoduleontheheatsink.Carefullyaligntheholesinthethermalpadwiththeheat-
sinkandmoduleholes.Ifheatsinkcompoundisusedinplaceofathermalpad,applyathincoatofeventhicknessto
themetalbottomofthemodule.Athicknessof0.002”–0.003”(0.050mm–0.075mm)isoptimum.Toomuchcom-
poundimpedesheattransferfromthemoduletotheheatsinkresultinginshortmodulelifeduetooverheating.
D. InsertthefourM6mountingbolts,butdonottighten.Leavethemlooseafewturns.Becertainthatthethreadsfrom
themountingboltsdonotbendtheedgesofthethermalpadclearanceholes.Abentthermalpadcanpreventthe
modulefromseatingproperly,impedingtheheattransferfromthemoduletotheheatsink.Theresultcanbemodule
damageduetooverheating.
E. Partiallytightenthefourmountingboltsalittlemorethanngertightintheorder:A-B-C-D.Seegurebelow.
F. Fullytighten,inthesameorderabove,toatorqueof35–44in-lbs(4.0–5.0N-M).Seegurebelow.
G. Installthebusplatesandbusbars.Becarefulthatthesheetsofinsulationseparatingthebusplatesarestillintheir
originalpositions.It’sagoodideatotightenthemountinghardwareonlyaftergettingitallstarted.TorquetheM6
moduleterminalhardwareto35–44in-lbs(4.0–5.0N-M).
H. Removethejumperplugsfromthemodulegateleadplugs,andplugintotheappropriateplugsfromthePWM/Gate
DrivePCBoard.SeeCautionbelow.
I. Replacethetoppanel.
The module gate plugs must be plugged into the PWM/Gate
Drive PC Board whenever the power source is in operation.
Failure to plug them in will result in damage to the module and
possible damage to the torch.
CAUTION
Four-PointMountingType
 Partialtightening-A
-B-C-D
 Fullytightening-A
-B-C-D
A
D
C
B
1
2
3
6 (RED)
7 (WHT)
Key Plug
Position 1 (RED)
1-IBGTCollector,FreeWheeling
Diode(FWD)Anode
2-IGBTEmitter
3-FWDCathode
6-IGBTGate
7-IGBTEmitter
threeleads