Baldor VS1GV21-1B, Installation & Operating Manual, Page: 146 / 204

11-2 Composite Reference Description MN765
Table 11-3 Composite Reference Parameters
Stage P# Description
1 3501 &
3503
Scale Factor - Monitor a parameter number (Variable A or B) and scales the value into percentage of
maximum value for use by the next stage. As an example, P3501=5 Motor Voltage (assume its maximum
is 230V) is monitored and internally 20% is computed for P5= 46 V or 10% for P5=23 V. Likewise, with
P3503=11 then Speed Demand (assume its maximum is 60 Hz) is monitored and 50% is output when
P11=30 Hz or –50% when P11= -30 Hz.
P3501 or P3503 can be can be set to any valid drive parameter number. If either is set to an invalid
parameter number Py=0% or Pb=0%.
P3501 or P3503 only point to a valid parameter number in the active parameter table, never a parameter
outside the active table. Switching parameter tables with the drive enabled causes the Composite
Reference to be redefined by the parameter values in the new active parameter table.
2 & 4 3502,
3504 &
3506
Math Function - These parameters select the mathematical functions to be applied at the second and
fourth stage of the Composite Reference's derivation. Refer to Table 11-1.
3 3505 Operator - This parameter provides the mathematical operation to be performed at the third stage of the
Composite Reference derivation. Refer to Table 11-2.
1 3507 &
3508
These parameters provide a way to scale up or down the percentage calculation of the first stage. They
range from -1000.00 to 1000.00 with default 1.00. Normally, the defaults work so these parameters need
not be changed.
A simple example of their use is: A 5A motor is connected to a 15A (peak) drive. When the motor is at
rated amps only 5/15 or 33.3% is passed on to stage 2, but by setting P3507=3.00, 100% is passed on
allowing full use of the motor’s current.
11.2 Composite Reference Examples
The following table gives examples of the kinds of Composite References that may be developed.
Table 11-4 Examples
Composite Reference Parameters
Description
P3501 P3502 P3503 P3504 P3505 P3506 P3507 P3508
P103 Identity P104 Identity Sum Identity 0.5 0.5
Average of Analog Inputs 1&2:
R
y
= (A
1
+A
2
)/2
P103 Identity P104 Freq Multiply Identity 1.0 1.0
Signal Generator with Magnitude
set by A1 and Frequency by A
2
:
R
y
= A
1
x Freq(A
2
)
P103 Identity P104 Identity Divide Identity 1.0 1.0 Ratio of Analog Inputs 1&2: R
y
= A
1
/A
2
P102 Square P104 Square Difference Square
Root
1.0 1.0
Square Root of Difference of Squares
of Process Error and Analog2:
R
y
= √(|P
e
2
– A
2
2
|)