Curtis 1244 Manual, Rev. E
37
3 — PROGRAMMABLE PARAMETERS: Current Limit Parameters
FIELD MAx
e maximum field current limit parameter defines the maximum allowed
current in the motor’s field winding. Its setting will determine the motor’s
maximum torque during both drive and braking, and will limit the power
dissipation in the field winding itself. e Field Max parameter is adjustable
from 7.5 amps to the controller’s full rated field current limit, in 0.5 amp incre-
ments. Recommendations for adjusting the Field Max parameter are provided
in Section6: Vehicle Performance Adjustment.
RESTRAINT
Because the 1244 controller is configured to provide throttle braking, overspeed
will cause the controller to create a braking current and thus limit or “restrain”
the overspeed condition. e restraint parameter, in combination with throttle
braking percent parameter, determines how strongly the controller will attempt
to limit the vehicle speed to the existing throttle setting. is function works
at all throttle settings, including zero throttle. It is applicable when throttle is
reduced or when the vehicle begins to travel downhill.
e restraint parameter is adjustable from 1 to 10. Setting the parame-
ter to a high value will cause strong braking, in an eort to bring the vehicle
speed down to the requested speed. Setting the restraint value to 1 will result
in minimal regen braking.
At zero throttle, the restraint function will also attempt to keep the motor
at zero speed. is will help hold the vehicle from running away down ramps
when braking to neutral is completed and the mechanical or electromagnetic
brake has not engaged. e higher the restraint parameter value, the stronger the
braking force applied to the motor and the slower the vehicle will creep down
the ramp. is creeping speed will depend on the restraint setting, the steepness
of the ramp, and the vehicle load. e restraint feature can never hold a vehicle
perfectly stationary on a ramp and is not intended to replace a mechanical or
electromagnetic brake for this purpose. e throttle braking percent parameter
is not active in this situation, and the controller will supply up to the maximum
programmed regen current limit. Recommendations for adjusting the restraint
parameter are provided in Section 6: Vehicle Performance Adjustment.
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