Specifications

Curtis PMC 1223/33, 1225/35, 1227/37 Manual
A-12
APPENDIX A: GLOSSARY
current limit value as the controller’s power section heats up. Variations of up to
10% of the specified 1-minute current limit rating may be observed in applica-
tions where the controller undergoes significant heating. Attention to controller
heatsinking will minimize this effect.
Temperature data
The temperature displayed in the 1307 programmer’s Test Menu is the instan-
taneous heatsink temperature at that moment, in degrees Celsius.
Thermal protection
Because of their efficiency and thermal design, Curtis PMC controllers should
barely get warm in normal operation. Overheating can occur, however, if the
controller is undersized for its application or otherwise overloaded. If the internal
temperature of the controller exceeds 90°C (194°F), the main current limit
decreases steadily until it is reduced to zero at 105°C (221°F). At the reduced
performance level, the vehicle can be maneuvered out of the way and parked.
NOTE: To prevent loss of braking effort, regenerative current limit is not cut back
in overtemperature conditions.
Full current limit and performance return automatically after the controller
cools down. Although this action is usually not damaging to the controller*, it
does suggest a mismatch. If thermal cutback occurs often in normal vehicle
operation, the controller is probably undersized for the application and a higher
current model should be used.
The controller is similarly protected from undertemperature. Should its
internal temperature fall below -25°C (-13°F), the current limit decreases to
approximately one-half of the set current. When the controller warms up, full
current limit and performance return automatically.
Throttle deadband (neutral deadband)
The throttle deadband is the pot wiper voltage range that the controller interprets
as neutral. The throttle deadband is typically set at 8%. A higher setting increases
the neutral range, which can be useful with throttle assemblies that do not return
reliably to a well-defined neutral point. The throttle deadband parameter is
programmable—see Section 3, page 36.
* Because braking current does not roll off in overtemperature,
motor braking down a steep slope with a heavy load for an
extended period could cause overheating of the MOSFETs.