英语翻译5.It is sometimes desirable or necessary to havemore tha

英语翻译
5.It is sometimes desirable or necessary to have
more than one final control element controlling
a single process.Often,this type of control
strategy requires that two to four Beck drives
each respond to different portions of one 4–20
mA Demand signal from the control system.
This type of operation is called split range
operation.For example,consider the most
common split range scenario—two drives split
ranged for 50% of the 4–20 mA Demand signal
input.Both drives are wired in parallel to receive
the same 4-20 mA signal (note that the total loop
resistance should be 250 Ohms as specified by
the HART® communications protocol.The 250
Ohm R11 resistor (see DCM-2 illustration on page
78) must be removed from one of the two drive
DCM-2 boards to allow HART® communications.
If more than two drives are split ranged,the R11
resistor must be removed from all the DCM-2
boards but one),but each drive’s interpretation
of the signal must be different.One drive must
interpret 4–12 mA as 0–100% Demand,and
one drive must interpret 12–20 mA as 0–100%
Demand.This requires that the drives have
different Demand signal calibrations.
Split-ranging is easily accomplished by
determining the break points (12 mA in the
example above) and using a HART communication
device.
First,navigate to the Configuration menu.
Next,select the Demand Setup submenu.
Change appropriate Demand range limit
accordingly.In the example above,one drive's
upper Demand range (DemRngUpr) would be
changed from 20.00 mA to 12.00 mA; and the
other drive's lower Demand range (DemRngLwr)
would be changed from 4.00 mA to 12.00 mA.
NOTE:Ensure that the L.O.S.(Loss of
Demand input signal) settings of the drives
are appropriate for the new configuration.
This would involve changing the appropriate
Demand LOS limits (DemLimLwr or
DemLimUpr).Typically,these settings are -5%
and 105% of the Demand range.See page 21
for a description of the LOS function.
别用翻译软件复制过来 不对的
1、Control drives are shipped with over-travel
limit switches factory-set for either 101° (11-159,
-209,-309,-409) or 91° (11-169,-269,-369,
-469) of travel unless otherwise specified at
time of order.Limit switches must be set inside
the range of the fixed,non-adjustable,built-in
mechanical stops to prevent stalling of the motor.
Limit switches can be reset to limit travel of the
output shaft to any angle down to a minimum of
60°.Auxiliary switches are set as shown in the
figure at left unless otherwise specified at time of
order.
2、Rotate the drive’s output shaft in the CCW
direction away from the CW travel limit.Note
the direction of rotation of the lobe of the cam.
The correct cam lobe motion is away from the
switch lever with the switch lever on the lower
part of the cam.If not correct,return to step 2
and reset the cam to the proper orientation.

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