5.0 CONFIGURATION
The
factory setup (FS) option procedure is used to configure the
509 for a specific application. For optional configuration procedures,
see Section 5.3.
The unit may be configured using the push-on jumpers already
positioned on the pin-forest. Pin-forest designations are illustrated
in Figure 5-4.
5.1
GLOSSARY
The
following terms and their definitions appear throughout the
following procedures:
|
DP1
|
Decimal
point 1.999 |
|
DP2
|
Decimal
point 19.99
|
|
DP3
|
Decimal
point 199.9
|
|
DRHZ
|
Dummy
right-hand zero
|
|
|
|
|
G
or S
|
Gain
expressed in counts per square root of mA
|
|
I1
or I3
|
Lowest
input current in mA
|
|
I2
or I4
|
Highest
input current in mA
|
|
|
|
|
R1
or R3
|
Reading
in displayed counts at input current I1 or
I3 |
|
R2
or R4
|
Reading
in displayed counts at input current I2 or
I4 |
5.2
FS PROCEDURE IMPLEMENTATION
Install decimal point and Dummy Right Hand Zero (DRHZ) jumpers
as shown in Figure 5-4. All four jumper pins must be installed
for the display to function properly.
Figure 5-1. Jumper Locations
5.3 COMPONENT ACCESS/ UNIT CALIBRATION
The unit is calibrated at the factory in accordance with
the relationship:
READING = 250 square root of Is-4.000
where
Is is signal current in milliamperes. When Is=20
mA, READING is 1000 counts. Due to the nature of the square root
calculation, readings taken for input currents below 4.016 mA
are extremely sensitive to ZERO pot adjustment. A zero adjust
range of +0.2, -0.1 mA is provided.
5.4 FIELD ADJUSTMENT PROCEDURE
Without
calibrated test equipment, proper zero adjustment can only be
approximated. Field adjustment is best made using a precision
calibrator as shown in Fig. 5.2. SPAN adjustment is set nominally
to 1000 counts at 20.000 mA. This range may be adjusted to vary
from 200 to 2000 counts. Although the SPAN adjustment is independent
of ZERO setting, displayed readings will appear to interact
because of the nonlinear response characteristic.
To set the scale and offset to any other value follow the instructions
below. Note that the transmitter output value at ZERO input
should not be used as a calibration point due to logical error.
This error is the result of the meter's search for the square
root of negative numbers.
- Verify
initial offset and span calibration as follows:
Input
~ 20.000 mA, record READING (R2) in table 5.2;
Adjust input to provide square root of READING (R2)
square root of 10 = R1, record input;
| Compute
M = |
(R2/R1)2
|
| Compute
Z = |
(M
x I1) - I2
M - 1
|
| Compute
G = |
R2
square root of I 2 - Z
|
- To
obtain a new setting of span and offset, compute the expected
reading for the new "ZERO" current (near 4.016 mA
but not at READING = 0). Use the values determined in step
1; i.e., compute the following values given the specified
parameters:
| New
SPAN = S |
New
ZERO = X |
G
= Sensitivity calculated in step 1. |
| R4
= S x sq. rt of (I4 - X) |
R3
= G x sq. rt. of (I3 - X) |
R5
= S x sq.rt. of (I3 - X) |
With the specified input, adjust the ZERO pot to obtain R3.
Set the input to the specified full scale and adjust the SPAN
pot to obtain the reading R4.
- After
these adjustments are made, return the current to I3
and verify that the calibration currents used produce the
specified SPAN and OFFSET (R5) readings.
An example
of this procedure is shown in Table 5-3.
Table 5.2
Table
5.3
5.5 TOOLS AND EQUIPMENT
#2
Phillips screwdriver
Jewelers' slotted screwdriver
Precision milliampere power source
or
10 V power supply, 4 1/2 digit DMM with milliampere range and
10 kOhm rheostat
Figure 5-2. 509-2 and 509-3 Case
Access
OR
Figure 5-3. Calibration Setup
- Remove
4 Phillips-head screws from the top of the 509 case, and lift
main unit from case (Figure 5-1).
- Select
the desired jumper configuration and install push-on jumpers
in locations indicated in Figure 5-4.
- Pull
off two sealing plugs that cover 509 span and zero potentiometer
screw heads.
- Set up
509 in calibration configuration (Figure 5-2).
|
