GE IC3645SR4W746HL1 Installation And Operation Manual page 7

BASIC OPERATION AND FEATURES
SX TRANSISTOR CONTROL
Page 8
Section 2. FEATURES OF SX FAMILY OF TRANSISTOR MOTOR CONTROLLERS
Section 2.1 Performance
Section 2.1.1 Oscillator Card Features
Section 2.1.1.a Standard Operation
With the accelerator at maximum ohms or volts, the creep speed can be adjusted by Function 2 of the Handset or a trimpot. The
field control section allows the adjustment of the field weakening level in order to set the top speed of the motor. This top speed
function (Minimum Field Current) is enabled when the armature current is less than the value set by Function 24 and the
accelerator input voltage is less than 1 volt. Top Speed can be adjusted by Function 7 of the Handset or a trimpot.
The percent on-time has a range of approximately 0 to 100 percent. The SX controllers operate at a constant frequency and the
percent on-time is controlled by the pulse width of the voltage / current applied to the motor circuits.
Section 2.1.1.b Creep Speed
With the accelerator at maximum ohms or volts (approximately 3.7 to 3.5 VDC), the creep speed can be adjusted by Function 2 of
the Handset. At creep speed, the ON time can decrease to approximately 5%, with the OFF time at approximately 95%. At full
transistor operation, this condition will be reversed (short OFF time, long ON time). This variation of ON and OFF time of the
oscillator varies the voltage applied to the motor, thereby varying the speed of the motor for a given load.
Section 2.1.1.c Control Acceleration and 1A Time
This feature allows for adjustment of the rate of time it takes for the control to accelerate to 100% applied battery voltage to the
motor on hard acceleration. The 1A contactor will automatically close 2.0 seconds after the controlled acceleration stops and
the accelerator input is less than 0.5 volts, or less than 200 ohms. Armature C/A is adjusted by Function 3 from 0.1 to 22 seconds.
Section 2.1.2 Current Limit
This circuit monitors motor current by utilizing sensors in series with the armature and field windings. The information detected
by the sensor is fed back to the card so that current may be limited to a pre-set value. If heavy load currents are detected, this
circuit overrides the oscillator and limits the average current to a value set by Function 4 and Function 8 of the Handset. The C/L
setting is based on the maximum thermal rating of the control. Because of the flyback current through 3REC, the motor current is
usually greater than battery current, except at 100% ON time.
Section 2.1.3 Braking
Section 2.1.3.a Plug Braking
Section 2.1.3.b Regenerative Braking to Zero Speed
November 2002