User Manual

18
Curtis 1268 Manual, Rev. D
FLD BRAKE MAX
The field brake max parameter sets the maximum value of field current per-
mitted during field braking when
FLD BRAKE is On. The field current defined by
FLD BRAKE MAX overrides the standard field map current below the speed defined
by
FLD BRAKE SPD.
When an EM brake is used, the amount of field current programmed by
FLD BRAKE MAX is applied for the max amount of time specified by EMB DELAY (see
Output Driver parameters) prior to locking the EM brake. A high value of
FLD
BRAKE MAX
helps to ensure the vehicle uses sufficient braking to slow to a stop
before locking the EM brake.
When the auxiliary output is used for a WalkAway relay
™ instead of an
EM brake, lower
FLD BRAKE MAX values are useful in providing softer braking
near zero speed. Setting the value too low may render the controller incapable
of sensing vehicle rollback. However, even though the anti-rollback function
may not be activated, the plug braking generated by the field current will still
act to slow the vehicle.
FLD BRAKE RATE
The field brake rate parameter defines how quickly the field current rises during
field braking when
FLD BRAKE is On, and is adjustable from 0 to 6. This index
value defines the time for the field current to rise to the programmed
FLD BRAKE
MAX, as shown in the examples below. The higher the setting, the faster the rise.
(In these examples,
FLD BRAKE MAX = 50.0 amps.)
INDEX FIELD CURRENT RANGE TIME OF RISE
1 0.0 – 50.0 A 3.2 seconds
6 0.0 – 50.0 A 0.5 seconds
When an EM brake is used, the field current rises until it reaches FLD BRAKE
MAX, maintains that current for the duration of EMB DELAY, at the end of which
the EM brake driver turns off, causing the brake to engage—if it has not already
been applied due to the vehicle having stopped or started to roll back.
3 — PROGRAMMABLE PARAMETERS: Acceleration Parameters
STRONGER
BRAKING