Magnetek DSD 412 - Page 77

DRIVE SETUP
77
2. Stopping Distance
The internal S-Curve velocity generator of
the Magnetek DSD 412 drive is digital in
nature and is therefore very repeatable. The
Accel/Decel time is fixed per the selected
rate adjustment setting. The time setting
represents the total acceleration time from
zero to rated speed (or vice-versa), and is
independent of any S-Curve selection. The
starting and stopping distance from and to
any other digitally pre-set speed can be pre-
calculated and will also be repeatable.
The distance traveled during deceleration to
zero or to a lower leveling speed will be:
S = Tsec x DeltaFPM/RatedFPM x
(LevelingFPM/5 + DeltaFPM/10) (inches)
Where DeltaFPM is the change in steady
state running speed in feet per minute
However there is fixed delay and an
uncertainty of actual time to recognize and
start obeying a logic command to start the
deceleration cycle. The fixed delay is 0.01
seconds and the uncertainty is 0.018
seconds maximum. During this time the
elevator will still be moving at running
speed, creating an uncertainty in the actual
stopping distance.
This delay plus uncertainty distance will be:
Serror ≤ RunningFPM x 0.028 x 12/60 =
RunningFPM x 0.0056 (inches)
So the total maximum stopping distance or
deceleration distance to leveling speed will
be:
Stotal ≤ Tsec x DeltaFPM/RatedFPM x
(LevelingFPM/5 + DeltaFPM/10) +
RunningFPM x 0.0056 (inches)
For multi-floor runs, the slow-down vane
switch must be at least that distance from
the landing or the floor may be missed.
For single floor runs, the acceleration
distance may be calculated similar to above,
without the uncertainty error. The slow-
down vane switch for the next landing must
be at least that far away from the beginning
of the run. The single floor target running
speed and/or accel/decel times must be
adjusted to meet the above criteria
conditions or the landing may be missed.
Note that if minimum flight time is desired a
different deceleration rate may be selected
to optimize the result. A longer decel time
can result in a faster flight time since less
time is spent at leveling speed. A second
set of accel/decel parameters may be
activated by use of the optional Ramp Rate
Select contacts.
An optimizing procedure would be:
1. Set the Accel Time and percent jerk for
ride quality.
2. For short runs, (i.e. where the distance
from the starting floor to the vane switch
is less than the distance from the vane
switch to the stopping floor) set the
target speed so that the accel distance
is less than the distance from the start to
the vane switch.
3. Set the Decel Time so that the stopping
distance is just a little less than the
distance from the vane switch to the
stopping floor.
4. For multi floor runs set the speed to
contract speed and set the decel time so
that the decel distance is just slightly
less than the distance from the vane
switch to the target floor. Other options
certainly exist.
Drive & Field Enable
The Drive & Field Enable contact input
enables the drive to run and also acts as a
command to fully energize the motor field.
Closing Drive & Field Enable in advance of
the Hardware Run, or Run-Up / Run-Down,
command will allow time for the motor field
to become fully energized for a minimum of
starting delays. When the Drive & Field
Enable circuit is open, the motor field circuit
will be energized at the stand-by current
level. If Field Enable remains ON for more
than 5 minutes without running the drive, an
F403 will occur and the Full Field condition
will be turned OFF.
RUN w/ DIRECTION & RUN-UP / RUN-
DOWN