Curtis 1244 User Manual page 91

APPENDIX A: GLOSSARY
Reverse polarity protection
Reverse voltage will damage the controller. Reverse polarity protection is provided
by including a diode in series with the control line as shown in the standard
wiring diagram, Figure 3. When this diode is used, reversing the battery's B+
and B- connections to an otherwise properly wired controller will not allow the
main contactor to be engaged. This protects the controller from being damaged
by the reverse polarity.
Safe commutation region
The safe commutation region includes all the combinations of field current and
armature current that allow proper commutation between the motor's brushes
and the armature. If the motor operates outside this region, arcing and severe
heating and brush wear will occur. The motor manufacturer should be able to
provide curves defining the safe combinations of field and armature current.
We highly recommend that you obtain these curves and use them when tuning
the 1244 controller to a particular motor.
Sequencing delay
Sequencing delay allows the interlock switch to be momentarily opened within
a set time (the sequencing delay), thus preventing inadvertent activation of
HPD or SRO. This feature is useful in applications where the interlock switch
may bounce or be momentarily cycled during operation. The sequencing delay
is programmable from 0 to 3 seconds, with 0 corresponding to no delay—see
Section 3, page 47.
Speed limiting
The maximum speed can be limited in each of the four modes. This is done in
two ways: through the maximum speed parameter (see Section 3, page 27) and
through the minimum field current limit parameter (see Section 3, page 36).
The latter (the Min Field parameter) is the primary means of adjusting vehicle
top speed. Guidelines for adjusting maximum speed are presented in Section
6: Vehicle Performance Adjustment.
Static-return-to-off (SRO)
The SRO feature prevents the vehicle from being started when "in gear" (i.e.,
with a direction already selected). Three types of SRO are available (along with
a "no SRO" option). Selection is made with the programmer—see Section 3,
page 42.
A-9
Curtis 1244 Manual,
Rev. E