2 9 J U N E 2 0 1 2 D R A F T
APPENDIX A: GLOSSARY
Curtis 1207B Manual
A-9
Reset
Almost all faults require a cycling of the KSI or brake input to reset the control-
ler and enable operation; see Fault recovery for exceptions.
Sequencing delay
Sequencing delay allows the brake to be cycled within a set time (the sequencing
delay), in order to prevent inadvertent activation of HPD or SRO. This feature
is useful in applications where the brake switch may bounce or be momentarily
cycled during operation. The delay can be set with the handheld programmer
from 0 to 3 seconds, where 0 corresponds to no delay.
Shunt field control
The shunt field of a compound motor can be directly controlled by using the
shunt winding driver (if the current requirement meets the contactor driver
specifications). The shunt is activated while a direction is selected, as long as
the controller is not in plug braking mode. A programmable delay is available
for the shunt drive. This delays the shunt turn-on until some time after the
reversing contactors have shuttled. The delay can be set with the handheld
programmer from 0 to 0.5 seconds, where 0 corresponds to no delay.
Smooth, stepless operation
Like all Curtis 1200 Series controllers, the 1207B allows superior operator
control of the vehicle’s drive motor speed. The amount of current delivered to
the motor is set by varying the “on” time (duty cycle) of the controller’s power
MOSFET transistors. This technique—pulse width modulation (PWM)—per
-
mits silent, stepless operation.
Speed settings
The maximum speed setting defines the upper-limit speed as a percentage of
PWM output at full throttle. The maximum speed settings in Mode 1 and
in Mode 2 are independently adjustable via the handheld programmer; the
maximum creep speed and the maximum emergency reverse speed are similarly
adjustable.
Static-return-to-off (SRO)
The SRO feature prevents the vehicle from being started when “in gear.” SRO
checks the sequencing of brake input—or of KSI
and brake input—relative to a
direction input. The brake input must come on before a direction is selected. If
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