GE SX Series Installation And Operation Manual

GE SX Series Installation And Operation Manual Manual pdf 7 page image

BASIC OPERATION AND FEATURESSX TRANSISTOR CONTROL Page 7RevisedMay 2003time of vehicle development. This setting must not bechanged by field personnel, without the permission of theOEM.Section 2.1.4.b Speed LimitsThis feature provides a means to control speed by limitingmotor volts utilizing three "adjustable speed limits. Thismotor volt limit regulates top speed of the transistorcontroller, but actual truck speed will vary at any set pointdepending on the loading of the vehicle. Each speed limitcan be adjustable with the Handset using Functions 11, 12,and 13.Section 2.1.5 Ramp OperationSection 2.1.5a Ramp StartThis feature provides maximum control torque to restart avehicle on an incline. The memory for this function is thedirectional switch. When stopping on an incline, thedirectional switch must be left in its original or neutralposition to allow the control to initiate full power whenrestarted. The accelerator potentiometer input willmodulate ramp start current.Section 2.1.5b Anti-RollbackThis feature provides retarding torque to limit rollbackspeed in the non-travel direction when the ACC pedal isreleased when stopping on a grade, or when the brakepedal is released when starting on a grade. This featureforces the vehicle to roll very slowly down the grade whenaccelerator or brake is released. Because the vehicle cangain significant speed during roll-back, the torque neededto re-start on the ramp is lower than an unrestricted roll-back speed.Section 2.1.6 On-Board Coil Drivers & Internal CoilSuppressionCoil drivers for the LINE contactor and fan motor are on-board the control card. This contactor must have a coilrated for the vehicle battery volts, and the fan should alsobe rated for battery volts.Section 2.2 System Protective OverrideSection 2.2.1 Static Return to Off (SRO)This inherent feature of the control is designed to requirethe driver to return the directional lever to the neutralposition anytime he leaves the vehicle and returns.Additionally, if the seat switch or key switch is opened, thecontrol shuts off and cannot be restarted until thedirectional lever is returned to neutral. A time delay ofapproximately 2 seconds is built into the seat switch inputto allow momentary opening of the seat switch, if a bump isencountered.Section 2.2.2 Accelerator Volts Hold OffThis feature checks the voltage level at the acceleratorinput whenever the key switch or seat switch is activated.If, at start up, the voltage is less than 1.8 volts, the controlwill not operate. This feature assures that the control iscalling for low speed operation at start up.Section 2.2.3 Pulse Monitor Trip (PMT)The PMT design contains three features which shut down,or lock out, control operation if a fault conditions occursthat would cause a disruption of normal vehicle operation: Look ahead Look again Automatic look again and resetThe PMT circuit will not allow the control to start under thefollowing conditions: The control monitors both armature and field FET's atstart-up and during running. The control will not allow the line contactor to close atstart-up, or will drop it out during running, if either thearmature or field FET's are defective, so as to causeuncontrolled truck movement.Section 2.2.4 Thermal Protector (TP)This temperature sensitive device is internal to the powertransistor (Q1) module. If the transistor's temperaturebegins to exceed the design limits, the thermal protectorwill lower the maximum current limit, and maintain thetransistors within their temperature limits. Even at areduced current limit, the vehicle will normally be able toreach sufficient speed. As the control cools, the thermalprotector will automatically reset, returning the control tofull power.Section 2.2.5 Low VoltageBatteries under load, particularly if undersized or morethan 80 percent discharged, will produce low voltages atthe control terminals. The SX control is designed for usedown to 50 percent of a nominal battery voltage of 36-84volts, and 75 percent of a nominal battery voltage of 24volts. Lower battery voltage may cause the control tooperate improperly, however, the resulting PMT shouldopen the Line contactor, in the event of a failure.