NLS XL-1 User manual

Non-Linear Systems
XL-1
Current Loop Meter
INSTRUCTIONS
OVERVIEW
The XL-1 is a digital current loop meter
with a unique feature that requires no
power supply for its operation. All the
power it needs is derived from the
current being measured. With field-
programmable scaling and offset
capability, you will find a variety of
applications in 4-20mA and 10-50mA
current loops. The display is 3⅟₂digits
with a 0.6-inch LCD display.
SPECIFICATIONS
Display: 0 to ± 1999 digits, 0.6-inch LCD
Accuracy: ± 0.1% rdg ± 1 digit
Decimal Location: May be positioned
by a Solder Blob for any of three
positions: X . X . X . X
Polarity: Automatic
Update Rate: 3 rdg/sec, nominal
Power: None required. The meter
derives the power it needs from the
current being measured.
Operating Temperature: 0°C to +45°C
Maximum Input Current: 50 mA
Minimum Input Current: 4 mA
Voltage Drop Across Meter:
•With SB4 closed (0.015Ɪ+2.5)
volts ±2%*
•With SB4 open (0.030Ɪ+2.5)
volts ±2%*
*Ɪis the loop current in mA
Input Z: 20 mA loop = 30 Ω
50 mA loop = 15 Ω
Overload Indication: With inputs
exceeding full scale Positive: +1,
Negative: -1
Weight: 3 ounces (85.05g)
MOUNTING DATA
A rectangular panel cutout is recom-
mended for mounting the instruments.
The recommended dimensions are:
92 mm (3.622 in)
43 mm (1.693 in)
The meters will also fit the DIN/NEMA
standard cutout, 92 mm x 45 mm (3.622
in x 1.772 in) and the widely used 99.7
mm x 42.72mm (3.925 in x 1.682 in)
cutout.
Any panel thickness from 1.524 mm
(0.060 in) to 4.57 mm (0.18 in) may be
used.
Figure 1. Case Dimensions
To mount the meter: insert the meter
from the front of the panel through the
cutout. Fit the mounting clips (2) in the
slots on the top and bottom of the meter
case. The foot of the clip should face
forward. Thread screw (2) into clips &
tighten the screw against the rear
surface of the panel to fasten the meter
in place.
CONNECTIONS
For all applications, the positive input
lead (current going into the meter) must
be connected to terminal 1. The
negative lead should be connected to
terminal 2. In applications where it is
necessary to reduce the voltage drop
across the meter, SB4 may be installed,
see Chart below.
Positive Terminal 1
Negative Terminal 2
Voltage Drop Across Meter
With 50 mA Current
SB4 OPEN
SB4 CLOSED
4.13 Volts
3.37 Volts
DECIMAL POINT POSITION
If a decimal display is desired, install a
solder blob on SB1, SB2 or SB3
depending upon which decimal point is
to be illuminated.
Dec. Location: X . X . X . X
Solder Blob: SB1 SB2 SB3
If decimal point is not desired, omit blobs.
CALIBRATION
Unless special factory calibration is
ordered, the XL-1 meters are factory
calibrated so that at 4 mA input causes
a display of 000 and a 20 mA input
causes a display of 100. If a different
calibration is required, proceed as
follows:
1. Calculate A, the counts per mA, from
the equation A=C-c/Ɪ-i where i is the
smaller of two currents in milliamperes,
Ɪis the larger current, c is the number
of counts displayed corresponding to i
and C is the number of counts corres-
ponding to Ɪ.

2. Set switches S1 and S2, the coarse
scale adjustments, as shown below.
The location of these switches is
shown in Figure 2.
A = COUNTS/mA_____
SB4 closed
SB4 open
S1
S2
0 - 24
0 - 49
On
Off
25 - 39
50 - 79
Off
Off
40 - 63
80 - 125
Off
On
3. Calculate B, the offset counts, from
the equation B=Ɪc-iC/Ɪ-i. For most
applications, B can be negative or
positive.
Switches
S5
S6
Negative Offset
On
Off
Positive Offset
Off
On
Figure 2. Component Location
4. Set switches S3 and S4, the coarse
offset adjustments as shown below.
B=Offset (Counts)
S3
S4
0 to -700
On
Off
-700 to -1000
Off
Off
-1000 to -1500
Off
On
5. Apply 4 mA current between
terminals 1 (+) and 2 (-) to obtain a
meter display.
6. Adjust the ZERO potentiometer
(Figure 2) until the display equals the
desired reading.
7. Set the loop current to 20 mA and
adjust the SCALE potentiometer until
the display equals the desired reading.
8. Repeat steps 5 & 6 until meter
displays the readings desired.
9. Step 8 completes the calibration.
However, the meter should be checked
at tow or three widely spaced inputs to
insure its proper functioning.
Sample Computation
Input
Display
4mA
000
20mA
100
Ɪ= 4mA; Ɪ= 20mA; c = 000; C = 100
100-0 100
A = ----------- = --------- = 6.25
counts/mA 20-4 16
(20 X 0) – (4 X 100) 400
B = ----------------------------- = -------
20 -4 16
= -25 counts offset
The Table in step 2 shows that switch
S1 should be set to ON, and S2 should
be set to OFF. The Table in step 4
shows that switch S3 should be set to
ON and S4 should be set to OFF. The
table in step 3 shows that switch S5
should be ON and S6 should be OFF.
Specifications Subject to Change
Without Notice
Thank you for choosing Non-Linear
Systems. Should you have any
questions please call, email or visit our
website at nonlinearsystems.com.
Non-Linear Systems
Originator of the Digital Voltmeter
San Diego, CA
619-521-2161
[e-mail]
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