Curtis MultiMode 1214-8 Manual page 29

Curtis 1214-/15-/19-8 Manual
Contactor drivers and circuits
The controller can accommodate three external contactors: forward, reverse, and
main. Some vehicles may have no main contactor, or the main contactor may be
wired directly to the KSI or brake signal, bypassing the controller.
Various protections provided for the contactor drivers ensure that the
contactors operate correctly; see "Fault detection" below.
Creep speed at first throttle
Creep speed is activated when a direction is first selected. The output maintains
creep speed until the throttle is rotated out of the throttle deadband (typically
10% of throttle). Creep speed is adjustable from 0 to 25% of the controller duty
factor. This adjustment can be made electronically via the handheld programmer.
Current limiting
Curtis controllers limit the motor current to a preset maximum. This feature
protects the controller from damage that might result if the current were limited
only by motor demand. PWM output to the power section is reduced smoothly
until the motor current falls below the set limit level.
In addition to protecting the controller, the current limit feature also
protects the rest of the system. By eliminating high current surges during vehicle
acceleration, stress on the motor and batteries is reduced and their efficiency
enhanced. Similarly, there is less wear and tear on the vehicle drivetrain.
The main current limit, plug current limit, ramp start current limit, emer-
gency reverse current limit, and optional neutral brake plug current limit are all
adjustable via the handheld programmer.
Three of these current limits—main, plug, and ramp start—are indepen-
dently adjustable in Mode 1 and Mode 2.
Current multiplication
During acceleration and during reduced speed operation, the Curtis controller
allows more current to flow into the motor than flows out of the battery. The
controller acts like a dc transformer, taking in low current and high voltage (the
full battery voltage) and putting out high current and low voltage. The battery
needs to supply only a fraction of the current that would be required if a resistive
APPENDIX A: FEATURES & FUNCTIONS
A-2