GE SX Series Installation And Operation Manual

GE SX Series Installation And Operation Manual Manual pdf 19 page image

DIAGNOSTIC STATUS CODESSX TRANSISTOR CONTROL Page 19Revised May 2003Section 4.4 Controller Mounting GuidelinesIn the design of the GE family of motor controls,performance assumptions were made based on heattransfer between the control and the ambient environment.The vehicle mounting surface acts as a heat sink, whichincreases the effective surface area for heat dissipation. Ifthis assumed heat transfer is not achieved during controlinstallation and operation, GE controllers will fall short oftheir anticipated performance. It should be noted that thecondition of the mounting surface, and the quality of theresulting interface between the control and the vehicle, cansignificantly hinder heat transfer from the control. Thepresence of contaminants, or of air voids created bysurface inconsistencies in either the vehicle or the control,degrade the control’s capacity for heat transfer. Thecontrol’s performance is de-rated proportionally as its ownthermal sensors reduce its operation to protect it fromdamage due to excessive heating.Contained within the software of the GE controls areseveral diagnostic status codes related to controllerthermal performance. Failure to follow these mountingrecommendations increases the likelihood of encounteringthese status codes, through no fault of the control itself,thus voiding controller warranty for units returned solelydue to the presence of these status codes.Careful surface preparation, including adequateapplication of thermal compound, as detailed in thefollowing paragraphs, must be completed during theinstallation of GE controls. There are many techniques forapplying thermal compound, and we have outlined oneapproach below that has shown to apply a consistentthickness of material.Section 4.4.1 Necessary ToolsGE recommends the use of the following components, orequivalent substitutions, during the control installationprocess:a) Thermal compound, (Dow Corning #340),maintained per the manufacturer’srecommendations and free of contaminantsb) 3/32” notched trowel, such as a Krusinadhesive spreader, model 00031c) Calibrated torque wrench (0 – 15 ft-lbs)Section 4.4.2 The GE Control Mounting SurfaceDuring the manufacture of the GE control, the surfaceflatness is maintained at 0.005” per linear inch (not toexceed 0.025” per 10.0 inches). The surface finish of the GEcontrol has an Ra (average roughness) of 64 (microinches),or better. This finish is consistent with cold rolled orextruded aluminum.Care should always be taken in the handling and storage ofcontrollers. The base of the control should be free fromnicks, bumps, protrusions or any other foreign object thatwould prevent the control from sitting flush with the vehiclemounting surface. Examine the base of the control to verifythat it is in good condition and free from damage orcontamination.Section 4.4.3 Vehicle Mounting SurfaceThe quality of the vehicle mounting surface is critical forthe optimum heat transfer between the control and theambient environment. Conduction through the base of thecontrol is the control’s only means of heat rejection. WhileGE controls are highly efficient, a few percent of theelectrical energy will be converted into heat. As previouslymentioned, if this energy is not dissipated through the baseof the control, a thermal protector will reduce theperformance of the control until the temperature stabilizes.For optimal heat transfer from control to vehicle, theflatness of the vehicle mounting surface should beequivalent to the flatness of the control surface (0.005” perlinear inch). Use a straight edge or dial indicator to verifythe mounting surface.The biggest hindrance to heat transfer is the presence ofrust, scale, weld splatter or paint on the vehicle mountingsurface. If any of these items are noted, prepare thesurface per the following guidelines:a) Clean the mounting surface with a rotary wirebrush until the metal surface is exposed.b) Using 80-100 grit emery paper, sand thesurface until the metal shines.c) Flush the surface clean with an appropriateliquid de-greaser or parts cleaner.Section 4.4.4 Application of Thermal CompoundDue to the minute differences in the control mountingsurface and the vehicle mounting surface, small pockets ofair will be created. These air pockets will add to the overallthermal resistance of the interface.To avoid these air pockets and improve thermalconductivity, thermal compound must be applied betweenthe GE control base plate and the vehicle mounting surface.The function of this compound is to conform to surfacediscrepancies, filling gaps and optimizing the metal-to-metal contact of the control and the vehicle.a) Prepare the two mounting surfaces (controland vehicle) as indicated above.b) Using a triangular notched trowel of 3/32”(.09” +/- .01), apply the grease to the vehiclemounting surface.c) Use straight, non-crossing strokes of thetrowel to apply the compound.d) Make multiple vertical passes until a uniformconsistency is achieved.