DATEL, Inc., Mansfi eld, MA 02048 (USA)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356
Email: sales@datel.com
Internet: www.datel.com
DCA-20PC Series
LED Display, Subminiature
DC Ammeters With
Built-In Shunts
Figure 1. DCA-20PC Series Simplifi ed Schematic
Features
Built-in shunts for digitally measuring dc
currents from 200uA to 20A!
Functionally complete---no additional
components required
Wide power supply inputs:
5 to 40Vdc for 5V/12/24V/28V applications
36-75V option for telecom supplies
8-36Vdc Isolated-supply models for
high-side shunts
20mV internal shunt minimizes power loss
Includes load connections for easy 3- or
4-wire operation
High resolution; Factory calibrated to
0.1% accuracy
Large, easy-to-read, LED display with 0.37"
(9.4mm) high digits
Available with red, blue or green LED displays
Subminiature 1.38" x 0.88" package
DATEL's new DCA-20PC Series are the fi rst digital dc ammeters to include built-in
shunts for measuring dc currents up to 20A. Six ranges provide for precision measure-
ment of dc currents from 200uA to 20A. These ammeters are 100% self-contained; no
calibration or user-supplied components are required---they even include terminal blocks
for your external load circuit, a feature that enables simple 3-wire operation!
Two shunt-confi gurations are offered: grounded-shunt ("low side"), 5-40V-powered
models for cost-sensitive applications, and 8-36V isolated-supply models for high side or
fl oating shunt applications. A versatile power supply design accommodates all popular
supply voltages from 5 to 75Vdc. Reverse-polarity-protected supply inputs ensure trouble
free installation. And, because many dc ammeters are installed in battery backup
applications, power consumption is typically below 1 Watt for 8-36V models, and below
75mW for 5-40V models. To further reduce overall power consumption, the voltage
dropped across its built-in series shunt is only 20mV!
DCA-20PC Series ammeters are housed in subminiature, 1.38" x 0.88" (35mm x
22mm), rugged packages that feature a large, 0.37"/9.4mm high, LED display. A built-in,
high-contrast color fi lter ensures that legibility is not compromised: the display can be
easily read at distances up to 15 feet (5 meters). Available LED-display colors include
brilliant blue, bright green, and standard red.
Built-in shunts, Precision electronics, miniature size, wide power supply inputs, low
power consumption, and no-hassle 3-wire installation make DCA-20PC Series the ideal
choice for all your 200uA to 20A ammeter-applications.
Order online at www.datel.com
A/D
CONVERTER
LED DISPLAY
INPUT
AMPLIFIER
POWER
CONVERTER
TB1
5V
+5V
TB2
POWER
GROUND
SIGNAL
GROUND
Open on isolated-supply models
Applies to isolated-supply models only
V
+V
LOAD (+)
+SHUNT
BUILT-IN
SHUNT
SHUNT
(V)
+
+
+
+
*
*
**
**
EXTERNAL
LOAD
EXTERNAL
DC SUPPLY
1
2
2
3
1
2
1
2
L E D D I S P L A Y , D C A M M E T E R S W I T H B U I L T - I N S H U N T S
DCA-20PC Series
2
DATEL, Inc., Mansfi eld, MA 02048 (USA)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356
Email: sales@datel.com
Internet: www.datel.com
Performance/Functional Specifi cations
Typical at T
A
= +25C, unless otherwise noted.
Input Range:
Full Scale Load Current
1 = 199.9A
2 = 1.999mA
3 = 19.99mA
4 = 199.9mA
5 = 1.999A
6 = 19.99A
Ordering Information
DCA-20PC - 1 - DC1 - R L
Order on-line at www.datel.com
Power:
DC1 = 5-40Vdc, non-isolated power
(available with red LEDs only)
DC4 = +8-36Vdc, isolated power
(available with red, green, or blue LEDs)
LED Color:
BS = Standard Blue
GS = Standard Green
RL = Low-Power Red
Accessories:
DMS-20-CP Panel
Cutout
Punch
Full Scale Load Current
Min.
Typ. Max. Units
DCA-20PC-1
199.9 Adc
DCA-20PC-2
1.999 mAdc
DCA-20PC-3
19.99 mAdc
DCA-20PC-4
199.9 mAdc
DCA-20PC-5
1.999 Adc
DCA-20PC-6
19.99 Adc
Overcurrent Rating( <6 Sec.)
1.5x rated full scale load current
Internal Shunt Resistance
DCA-20PC-1
100 Ohms
DCA-20PC-2
10 Ohms
DCA-20PC-3
1.0 Ohm
DCA-20PC-4
0.1 Ohm
DCA-20PC-5
0.01 Ohm
DCA-20PC-6
0.001 Ohm
Shunt Input to Power Supply Isolation
DCA-20PC-X-DC4 models only
500
Vdc
Performance
Sampling Rate
2.5 samples per second
Accuracy
0.15%FS
Temperature Drift (0 to 60C)
0.2 0.4 Cnts/C
Zero-Current Reading
-001
000 001 Cnts
Operating Supply Voltage (TB2 Terminals 1, 2 and 3)
DCA-20PC-X-DC1-XX
+5.0
+40 Vdc
DCA-20PC-X-DC4-XX
+8
+36 Vdc
Operating Supply Current (TB2 Terminals 1, 2 and 3)
DCA-20PC-X-DC1-XX (@5-40V)
10 15 mAdc
DCA-20PC-X-DC4-XX (@8V)
100 150 mAdc
DCA-20PC-X-DC4-XX (@36V)
25 40 mAdc
TB1& TB2 Terminal Blocks
Wire Size
12-20AWG, (solid)
14-20AWG (stranded) copper wire
Insulation Strip Length
0.250 inches
Screw Tightening Torque
4.4 pound-inches (0.5Nm)
Rated Current
20A with 12AWG solid copper
wire; 15A with 14AWG solid or
standed copper wire
Display
Display Type and Size
3 Digit, 0.37"/9.4mm high, red,
blue, or green LED
Overrange Indication
"1___" for positive current
"1___" for negative current
Display Reading/Decimal Point
Model dependent
Physical/Environmental
Operating Temperature
0
+60 C
Storage Temperature
40
+75 C
Humidity (non-condensing)
0
85 %
Case Material
Polycarbonate
Dimensions
1.38"W x 0.88" x 1.0" nominal
Weight (all models)
0.6 Ounces (17 grams) nominal
The noted full-scale values are the external load currents that the ammeter is
designed to measure. This current enters TB-1 (-SHUNT), passes through the
ammeter's built-in shunt and exits via TB1-2 (+SHUNT). For all models, this
same full-scale load current can also be routed, if the user so chooses, through
TB2-1 and TB2-2 (connection to positive rail of power supply). See detailed
wiring diagrams.
Measuring positive and negative currents (bipolar operation): In applications
where both positive and negative currents must be measured, DATEL recom-
mends using `-DC4' 8-36V isolated supply models. Negative current fl ow is
denoted by the illumination of the display's negative (-) sign; the absence of
a negative sign implies positive current fl ow. Contact DATEL if you have any
questions regarding bipolar operation of DCA-20PC ammeters.
For all models, the application of 1.5 times the rated full-scale load current is
permissible as long as this overcurrent condition does not exceed 6 seconds and
occurs no more than once in a 60 second interval (10% duty cycle).
Breakdown (isolation) voltage applies only to `-DC4' isolated-power models.
Breakdown voltage is tested with TB1-1 tied to TB1-2 (-SHUNT shorted to
+SHUNT), and TB2-1, TB2-2, and TB2-3 all tied together (+V shorted to -V).
500Vdc is then applied between the two shorted terminal-block pairs; the maxi-
mum permissible leakage current is 5uA.
Zero reading is measured with TB1-1 (-SHUNT) shorted to TB1-2 (+SHUNT).
The Operating power supply voltage is applied to TB2-1-2 (+V) and TB2-3 (-V)
on `-DC4' models, and to TB1-1 (-SHUNT) and TB2-2 (+V) on `-DC1' models. On
all models, TB2-1 and TB2-2 are internally tied together (+V). Operating supply
current is the current which powers the meter's analog and digital circuits; it is
measured with zero load-current passing through the ammeter's built-in shunt
(i.e., with the display reading "000" and one decimal point enabled).
On 5-40Vdc powered (`-DC1'), grounded-shunt models, the ammeter's operating
supply current enters TB1-1 (-Shunt) but is not included in the displayed reading
(i.e., it does not pass through the built-in shunt).
A DMS-BZL4 bezel assembly with sealing gasket is
supplied with each ammeter.
L E D D I S P L A Y , D C A M M E T E R S W I T H B U I L T - I N S H U N T S
DCA-20PC Series
3
DATEL, Inc., Mansfi eld, MA 02048 (USA)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356
Email: sales@datel.com
Internet: www.datel.com
1
CAL
DCA-20PC-X-DC1-XX
SHUNT
MUST BE
IN LOW SIDE
TB2-1 AND TB2-2
ARE INTERNALLY
SHORTED
1
2
TB2
1
2
TB1
SHUNT
(V)
+
+
+V
+V
LOAD CURRENT
LOAD
DC SUPPLY
5-40Vdc
+SHUNT
1
2
J3 MUST BE
INSTALLED
(FACTORY SETTING
FOR 5-40Vdc SUPPLIES)
J3
J3
Technical Notes
Figure 2. Low-Side Shunt Connections for "-DC1"
5-40Vdc Non-Isolated Supply Models
Figure 3. Low-Side Shunt Connections for "-DC1" Models Modifi ed for
36-75Vdc Non-Isolated Power (See Technical Note 6)
To ensure safe and reliable operation, DCA-20PC dc ammeters
must be installed and serviced by qualifi ed technical personnel.
DC ammeter applications can expose a user to potentially lethal
currents and voltages. Power and load connections must be made
with all associated power sources de-energized. Contact DATEL if
you have any questions regarding installation or operation of any
of our digital instruments.
However, in some applications, regulations can limit the continuous cur-
rent fl owing in 14AWG solid or stranded copper wire to 15A maximum.
4. High-Side versus Low-Side Shunts: Incorrect shunt connections
are one of the most common problems encountered when applying
digital dc-ammeters. Incorrect shunt connections can cause permanent
damage to the ammeter and its associated equipment.
1
CAL
DCA-20PC-X-DC1-XX
SHUNT
MUST BE
IN LOW SIDE
TB2-1 AND TB2-2
ARE INTERNALLY
SHORTED
REMOVE J3
FOR 36-75Vdc
SUPPLIES
1
2
TB2
1
2
TB1
+
+
LOAD
DC SUPPLY
36-75Vdc
SHUNT
(V)
+V
+V
LOAD CURRENT
+SHUNT
1
2
J3
J3
1. Calibration: DCA-20PC ammeters are factory calibrated using a high-
precision current source. Under normal indoor operating conditions,
periodic recalibration is not necessary. The calibration potentiometer,
located on the back of the ammeter, is a turn type; do not force its
adjustment screw past the two end stops. If recalibration is necessary,
it must be performed by qualifi ed personnel. Calibration is performed
by applying a precision current source to TB1's -SHUNT and +SHUNT
terminals. For best results, use a load current that is approximately 95%
of the ammeter's full-scale rating.
The calibration current source and power supply inputs must be con-
nected per the appropriate model-specifi c wiring diagram shown later
in this data sheet. Using an insulated slotted tool, adjust the calibration
potentiometer until the display is within 1 count of the desired reading.
Please note, the potentiometer provides an adjustment range of approx-
imately 1%. Contact DATEL if additional information is required regard-
ing calibration or setup of DCA-20PC ammeters.
2. Wiring and Fusing: Power supply (TB2) and input (TB1) wiring must
be rated for the electrical and environmental conditions under which the
ammeters will be operated. They must also comply with any regulatory
or application-mandated requirements pertaining to the user's installa-
tion. Connections to DCA-20PC ammeters must be made with all power
sources de-energized. Refer to the Functional Specifi cations section for
detailed wire type and wire gauge information.
DCA-20PC ammeters' power supply and shunt terminals are not inter-
nally fused. Therefore, the supply wires connected to both the meter
and the load must be fused according to the maximum current rating (or
lower) of the wire gauge used, in accordance with applicable regulatory
codes.
Wiring Insulation should be stripped to within +/-10% of the stated
dimensions. All wires must be inserted into the terminal block openings
such that the screw terminal does not pinch any insulation. After fi nal
assembly, inspect all terminal block connections for shorts between
adjacent conductors; this step is particularly important when using
stranded wire.
3. Terminal Block Torque Ratings and Wire Size: It is important to
tighten all TB1 and TB2 screw-terminals to their torque specifi cation
of 4.4 pound-inches (0.5Nm). Proper tightening will minimize thermal/
electrical losses and ensure reliable operation. Under severe operation
conditions (for example, vibration, high continuous load currents, and
wide variations in ambient temperature), 25% over-tightening is permis-
sible. Applications subject to vibration should use stranded wire.
Proper terminal block torque is extremely important on all 20A models
(DCA-20PC-6 part numbers). Loose connections can overheat, thereby
posing a potential fi re hazard to the terminal blocks, the load and supply
wiring, the ammeters themselves, and nearby equipment. 20A models
must use either 14AWG stranded or 12 AWG solid copper wires only.
L E D D I S P L A Y , D C A M M E T E R S W I T H B U I L T - I N S H U N T S
DCA-20PC Series
4
DATEL, Inc., Mansfi eld, MA 02048 (USA)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356
Email: sales@datel.com
Internet: www.datel.com
Figure 4. High-Side Shunt Connections for "-DC4"
8-36Vdc Isolated-Power Models
Figure 5. Using "-DC4" Isolated-Power Models to Maintain Isolation
Between Two Power Supplies
Figure 6. Using "-DC4" Isolated-Power Models
in Low-Side Shunt Applications
Low-side shunts: Applications that employ a single power supply to
power both the load and the ammeter, and the external shunt is located
in the negative side of the supply (commonly referred to as "low side"
or "grounded shunt") should use `-DC1' non-isolated power DCA-20PC
Series ammeters. Figures 2 and 3 depict typical low-side shunt connec-
tions.
High-side shunts: `-DC4' 8-36Vdc isolated-power models must be
used in all applications that employ a single power supply to power
both the load and the ammeter and the shunt is located in the high side
(positive terminal) of the power supply. Figures 4 and 5 depict typical
high-side shunt connections. As shown in Figure 5, `-DC4' isolated-
power models can also be used in applications where one supply
powers the ammeter and a second supply powers the load, but the two
supply-grounds cannot be tied together. `-DC4' models include a built-in
dc/dc converter to provide a minimum 500Vdc isolation between the
shunt (TB1) and power supply (TB2) inputs.
5. Replacing Analog Panel Meters: DCA-20PC ammeters can be used
as replacements for analog panel meters if a suitable dc voltage
is available for powering the ammeter. In retrofi t applications, it is
important to determine the shunt's electrical confi guration (i.e., high or
low side). If any doubt exists as to the shunt's location, use only `-DC4'
isolated-supply models. All rewiring must be performed with the load
and power supply de-energized.
6. Operation With 36 to 75Vdc Power: As shipped, all `-DC1' models'
rated operating supply range is +5 to +40Vdc. However, `-DC1' models
can be user confi gured for 36 to 75Vdc operation by removing (open-
ing) jumper J3. Please note that this modifi cation can only be per-
formed on `-DC1' power models. Also, all `-DC1' models including
those that have been modifi ed for 36-75Vdc operation can only be
connected in low-side, grounded-shunt applications. See Figure 3 for
CAL
1
1
2
3
TB2
1
2
TB1
+
+
V
LOAD
TB2-1 AND TB2-2
ARE INTERNALLY
SHORTED
DCA-20PC-X-DC4-XX
SHUNT IS IN
HIGH SIDE
SHUNT
+V
+V
LOAD CURRENT
+SHUNT
DC SUPPLY
8-36Vdc
CAL
1
1
2
3
TB2
1
2
TB1
+
+
V
LOAD
DC SUPPLY
8-36Vdc
TB2-1 AND TB2-2
ARE INTERNALLY
SHORTED
DCA-20PC-X-DC4-XX
SHUNT IS IN
LOW SIDE
SHUNT
+V
+V
LOAD CURRENT
+SHUNT
CAL
1
1
2
3
TB2
1
2
TB1
+
+
+
V
+V
LOAD
CURRENT
LOAD
DC SUPPLY #1
8-36Vdc
+SHUNT
SHUNT
TB2-1 AND TB2-2
ARE INTERNALLY
SHORTED
DCA-20PC-X-DC4-XX
DC SUPPLY
#2
SHUNT IS IN
HIGH SIDE
L E D D I S P L A Y , D C A M M E T E R S W I T H B U I L T - I N S H U N T S
DCA-20PC Series
5
DATEL, Inc., Mansfi eld, MA 02048 (USA)
Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356
Email: sales@datel.com
Internet: www.datel.com
Step 1.
Step 2.
Step 3.
Step 4.
Panel Installation
All connections and modifi cations must be made after the ammeter is
securely attached to the panel, with all load and supply voltages de-
energized (off).
The installed wire-positions should be such that minimal forces are applied to
TB1, TB2, and the ammeter itself. In high-vibration environments, the use of
wiring strain-reliefs is recommended.
To insure a secure panel-mount installation, DATEL recommends using the
DMS-BZL4 (with sealing gasket) bezel assembly supplied with each ammeter.
Figure 8. Panel Installation
See the Mechanical Specifi cations section for detailed panel cutout and
ammeter dimensions.
Following the four-step sequence shown in Figure 8 below, being careful
not to apply excessive force or twisting motions, insert the ammeter into the
panel opening. When using the DMS-BZL4's sealing gasket, make sure it
is positioned between the ammeter's fl ange and the panel's front surface.
Be sure to use and securely tighten all four screws supplied with the bezel
assembly.
PANEL
PANEL
PANEL
2
1
PANEL
3
4
BEZEL
GASKET
(optional)
detailed wiring information. Any reconfi guration of J3 must be made
prior to connecting the power supply and load to the ammeter.
7. Decimal Points: DCA-20PC ammeters' decimal points are factory
confi gured for the respective full-scale input range. However, the deci-
mal points serve as placeholders only, they have no affect on the
ammeter's displayed accuracy or resolution.
If desired, an alternative decimal point by can be enable by opening the
factory closed solder gap and then closing one of the other two solder
gaps. The closing of SG1, SG2, or SG3 selects DP1 ("1.XXX"), DP2
("1X.XX"), or DP3 ("1XX.X"), respectively.
8. Noisy Power Supplies: Some power supplies contain high-frequency
switching devices that may conduct and/or radiate signifi cant noise
onto the low-level signal developed across the internal shunt. Even
though DCA-20PC ammeters incorporate built-in input fi ltering, some
portion of this noise may be amplifi ed and subsequently measured by
its sensitive input circuitry. The amplifi ed noise introduces errors that
are particularly noticeable at zero load current (i.e., the ammeter may
not display a relatively steady "000" reading).
Connecting an external, unpolarized capacitor across TB1's -SHUNT
and +SHUNT inputs can help reduce noise-related display errors. In
certain situations, the use of twisted pair or shield wiring may be
required. As a general rule, avoid using excessively long leads between
the ammeter and the load.
9. `Power ON' LED: DCA-20PC ammeters include a rear-mounted `Power
On' LED. The bright illumination of this LED indicates that the meter's
1
CAL
DCA-20PC-X-DC1-XX
1
2
TB2
1
2
TB1
SHUNT
(V)
+
+
+V
LOAD CURRENT
LOAD
DC SUPPLY
5-40Vdc
+SHUNT
SHUNT
MUST BE
IN LOW SIDE
1
2
J3
J3
Figure 7. 3-Wire Connections for "-DC1"
5-40Vdc Powered Models
internal power converter is operational. It does not signify that the
ammeter and the external load are connected correctly.
DATEL, Inc. 11 Cabot Boulevard, Mansfi eld, MA 02048-1151
Tel: (508) 339-3000 (800) 233-2765 Fax: (508) 339-6356
Internet: www.datel.com Email: sales@datel.com
DATEL (UK) LTD. Tadley, England Tel: (01256)-880444
DATEL S.A.R.L. Montigny Le Bretonneux, France Tel: 01-34-60-01-01
DATEL GmbH Mnchen, Germany Tel: 89-544334-0
DATEL KK Tokyo, Japan Tel: 3-3779-1031, Osaka Tel: 6-6354-2025
DATEL makes no representation that the use of its products in the circuits described herein, or the use of other technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein do
not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifi cations are subject to change without notice. The DATEL logo is a registered DATEL, Inc. trademark.
DCA-20PC Series
L E D D I S P L A Y , D C A M M E T E R S W I T H B U I L T - I N S H U N T S
DS-0518
B 03/03
Mechanical Specifi cations
ISO 9001
Registered
#2-56 INSERT
0.156 (3.96) DEEP
FRONT VIEW
1.280
(32.51)
0.187
(4.75)
DMS-BZL4 BEZEL
RECOMMENDED DRILL AND PANEL CUTOUT DIMENSIONS
1.826 (46.38)
0.838
(21.29)
1.626 (41.30)
1.07
(27.18)
INTERNAL CORNER RADII:
0.032 (0.81) MAX.
0.093 (2.362) DIAMETER (4 REQUIRED)
ONLY WHEN USING SUPPLIED BEZEL ASSEMBLY
0.116 (2.95)
1.336 (33.93)
0.145 (3.68)
MECHANICAL DIMENSIONS: Inches (mm)
TOLERANCES: 2 PL DEC 0.02 (0.51)
3 PL DEC 0.010 (0.254)
0.80
(20.3)
0.88
(22.4)
1.30
(33.0)
0.040
(1.02)
1.04
(26.4)
0.475
(12.1)
0.040
(1.02)
1.38
(35.1)
1.42
(36.1)
1
CAL
J3
1
2
1
2
TB2
1
2
TB1
CAL
1
1
2
3
TB2
1
2
TB1
FRONT VIEW
ALL MODELS
BACK VIEW
DCA-20PC-X-DC4 MODELS
SHUNT
DP1
DP2
DP3
SG1
SG2
SG3
SG1
SG2
SG3
SHUNT
+SHUNT
+SHUNT
+V
V
+V
+V
+V
BACK VIEW
DCA-20PC-X-DC1 MODELS
PDF 
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