Wesley BCT-6200-6SA - Manual (Page 32)

Curtis 1243
GEN
2 Manual, Rev. B 24
Fig. 13 Ramp restraint
maps for controller with
Field Min set at 3 amps,
Field Max at 18 amps,
and braking current limit
at 300 amps.
BRAKING CURRENT (amperes)
F
IE
LD
C
U
R
R
E
N
T (am
peres)
300 250 200 150 100 50 0
25
20
15
10
5
0
Field Max
= 18 A
Field Min
= 3 A
Brake C/L
= 300 A
Restraint = 25
A
Restraint = 15
A
Restraint = 10
A
Restraint = 3 A
Restraint = 35
A
At zero throttle, the restraint function tries to keep the motor at zero speed,
which helps hold the vehicle from running away down ramps. The higher the
restraint parameter value, the stronger the braking force applied to the motor
and the slower the vehicle will creep down ramps. This creeping speed depends
on the restraint setting, the steepness of the ramp, and the vehicle load weight.
The 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.
The restraint parameter establishes a linear mapping of field current to
braking current, and is adjustable from the programmed minimum field (Field
Min) up to the controller’s full rated field current. As shown in Figure 13, it is
limited by the programmed maximum field (Field Max). Setting the restraint
parameter to a high value will cause strong braking, in an effort to bring the
vehicle speed down to the requested speed. Extremely high values may cause
the vehicle speed to oscillate (“hunt”) while in ramp restraint.
The restraint parameter is tuned as part of the vehicle performance ad-
justment process (Section 5).
M1–M4, BRAKE RATE
The braking rate defines the time it takes the controller to increase from 0%
braking output to 100% braking output (as defined by the corresponding
mode-specific brake current limit) when a new direction is selected. A larger
value represents a longer time and consequently gentler braking. Faster braking
is achieved by adjusting the braking rate to a smaller value. The braking rate
is adjustable from 0.1 second to 3.0 seconds.
Note: The variable braking parameter must be programmed Off for the
braking rate parameter to apply; if variable braking is On, the braking rate will
be determined by throttle position rather than the programmed braking rate.
3 — PROGRAMMABLE PARAMETERS: Braking Parameters