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Page 25
Revised 7/95 DFS-1 Manual
POWERTEC Ind. Corp.©
As a Speed Reference input ( ...01h), Analog
input #1 sets the speed of the controlled motor
directly if the DFS-1 is set up in Master Mode
(parameter #5 - VL2 VL1).
If the DFS-1 is in SLAVE mode, Analog Input
#1, when set to ...01h will act as a Ratio SETPOINT.
The External Torque Limits are used to set limits
on the motor current which are below the current
limit level. When parameter #5 VL4 VL3 is set to 00
01h, or 00 02h, Analog Input #1 may be set to ...03h
or ...04h respectively to supply the torque limiting
reference.
The External Horsepower Limit sets the maxi-
mum horsepower produced by the drive. Horsepower
is the PRODUCT of speed and torque. When motor
speed is low, motor current is high, and when speed
is high, current is low. The drive increases speed until
sufficient load is developed and the product of load
and speed equals the setpoint. After that is achieved,
increasing load reduces speed, and decreasing load
increases speed.
18. ANALOG INPUT #1 SIGNAL
CONDITIONING
USE PARAMETER #17 TO SELECT THE FORM
OF THE SIGNAL AT ANALOG INPUT #1.
RANGE OF VALUES: 0000 0000h to 0000 001Fh
0 TO 32 (decimal)
Default Value: 0000 0001h 1 (decimal)
Six types of signals will be accepted by Analog
Input #1. Parameter #18 selects the form of signal to
be processed.
The six types of signals are:
0000 0000h -10VDC to +10VDC
bipolar voltage input with zero
center value
0000 0001h 0 to +10VDC
unipolar voltage signal
0000 0002h 0 to +5VDC
unipolar voltage signal
0000 0003h 1 to +5VDC
unipolar voltage signal
0000 0004h 0 to 20mA
unipolar current signal
0000 0005h 4 to 20mA
unipolar current signal
0000 0006h to 0000 001Fh
Undefined - Reserved for
future use
If an undefined mode (...06 through ...1F) is
selected, Analog Input #1 will be inoperative.
Choosing the incorrect signal conditioning for
the actual input signal will result in erratic operation.
19. ANALOG INPUT #1 LOW
ENGINEERING UNITS (EGU)
USE PARAMETER #17 TO SELECT THE
THRESHOLD OF ANALOG INPUT #1 EFFECT.
RANGE OF VALUES: FFFE 7961h to 0001 869Fh
-99,999 to +99,999(dec.)
Default Value: 0000 0000h 0 (decimal)
(See Parameter 14 for the definition
and purpose of EGU)
Parameter #19 sets the threshold level for
effectiveness of Analog Input #1 at the lowest signal
level.
Assume that the maximum speed of the 1750
RPM motor is set to 12500 EGU’s in parameter #14
(representing, perhaps, 125.00 RPM on an extruder
screw) and the Analog input is set for a Speed
Reference Input of 0 to +10VDC. The default value
of parameter 19 is 0. This means that when 0VDC is
present at Analog Input #1, the result will be zero
speed.
Now, if we want to set a minimum speed on this
system, we can set a value of 500 in parameter #19.
This means that when 0VDC is present at Analog
Input #1, the motor will run at a speed of 500/12500
or 4 percent (70 rpm) of the maximum speed of the
motor. (see also parameter #20).