Murata ACA-20RM True-rms-ac ammeters with built-in ct Datasheet

ACA-20RM Series
True-RMS-AC Ammeters with Built-in CT
FEATURES
N
Built-in CTs provide true-rms values of complex
waveforms
N
Perfect for measuring AC current in IT applications
N
Five ranges measure: 0-0.2A, 0-2A, 0-20A, 0-30A
and 0-50A
N
50A models features a split-core CT for easy installation
N
Self-powered from 85-140Vac or 170-264Vac
N
Large, easy-to-read, red LED display with 0.37” digits
N
Reliable single-board construction
N
Digital replacement for analog meters
N
UL and CSA recognized components
Murata Power Solution’s new ACA-20RM Series are the world’s first digital ac-ammeters
to incorporate a built-in current transformer (CT) to directly measure the true-rms value of
complex, non-sinusoidal ac currents from 2 to 50A – no bulky and expensive 5A “donut”
CTs are required! Operation and setup is straightforward: simply pass the load-carrying
wire through the on-board CT, apply power, and the ammeter is fully operational.
Five input ranges measure 0-0.2 amps (0.1mA resolution), 0-2 amps (0.001A resolution),
0-20 amps (0.01A resolution), 0-30 amps (0.1A resolution) or 0-50 amps (0.1A resolution).
The 50A model features an oversized split-core current transformer that easily accommodates wires sizes up to 4 AWG (21.2mm2). Two power supply options are available: 85-140V
(47-63Hz), and 170-264V (47-63Hz).
All models are totally self-contained; no external components are required. Power consumption from a nominal 120V or 220V ac supply is less than 50mA. And, precision autozeroing circuitry, super-stable components, and an rms-to-dc converter circuit combine to
achieve excellent performance when measuring the complex, non-sinusoidal, ac currents
found in today’s computer/telecom equipment.
ACA-20RM Series ammeters feature full-size, 0.37” (9.4mm) high, 3½ digit, bright red
LED-displays and a built-in bezel/filter assembly that features metal fasteners. They are
panel-cutout compatible with MPS’s DMS-20 Series of ac voltage and frequency monitors,
making ACA-20RM ammeters perfect replacements for older, less reliable, analog panel
meters in today’s sophisticated IT instrumentation.
CAL.
+
3½ DIGIT
A/D CONVERTER
–
+V
–V
LED DISPLAY
RMS-to-DC
CONVERTER
(L1)
BUILT-IN
CURRENT
TRANSFORMER
POWER
CONVERTER
A
B
TB1
For full details go to
www.murata-ps.com/rohs
MEASURED AC
LOAD CURRENT
www.murata-ps.com
AC INPUT POWER
Technical enquiries email: [email protected], tel: +1 508 339 3000
MPM_ACA-20RM_B02 Page 1 of 5
ACA-20RM Series
True-RMS-AC Ammeters with Built-in CT
Performance/Functional Specifications
~ Specified full-scale currents are those passing through the ammeter’s built-in
current transformer’s primary load-circuit. See Notes 2 and 3 below for additional model-specific information.
Typical at TA = +25°C, unless otherwise noted.
Min.
Typ.
Max.
Units
ACA-20RM-O-ACX-RL
–
–
199.9
mA
ACA-20RM-1-ACX-RL
–
–
1.999
A
ACA-20RM-2-ACX-RL
–
–
19.99
A
ACA-20RM-4-ACX-RL
–
–
50.0
A
ACA-20RM-5-ACX-RL
–
–
30.0
A
Rated Full-Scale Current ~
1.5 x Rated Full-Scale Current
Overcurrent Rating 
Performance
Sampling Rate
RMS Responding, Crest Factors of 1-5
Temperature Drift (0 to 60 °C)
–
±0.2
±0.4
Cnts/°C
Zero-Current Reading (within
30 sec.)
–001
000
001
Cnts
Dielectric Withstanding Voltage
2000
–
–
Vdc
ACA-20RM-X-AC3-RL
85
120
140
Vac/47-63Hz
ACA-20RM-X-AC4-RL
170
220
264
Vac/47-63Hz
ACA-20RM-X-AC3-XX
–
30
50
mA/47-63Hz
ACA-20RM-X-AC4-XX
–
30
50
mA/47-63Hz
Power Supply Voltage
Power Supply Current 
Power Supply Terminal Block
Wire Size
16-22AWG, Solid and stranded
Insulation Strip Length
0.250 inches
Screw Tightening Torque
3.6 pounds-inches (0.4Nm)
Rated Voltage
310Vac
Display
Display Type and Size
3½ Digit Red LED, 0.37”/9.4mm High
Overrange Indication
“1___”
Decimal Point
Fixed, model dependent
(see full-scale input Current)
Physical/Environmental
Operating Temperature
0
–
+60
°C
Storage Temperature
–40
–
+75
°C
Humidity
–40
–
+95
%
Dimensions (non-condensing)
€ Specified accuracy applies to inputs with crest factors (CF) up to 2.0, where CF
= Vpeak/Vrms. Crest factors of 2 to 5 introduce an additional error of ±3% of full
scale. Ammeters are calibrated with a near full-scale 60Hz sine-wave current
flowing through the ammeter’s built-in CT.
 All specified maximum power supply currents are steady state; larger surge
currents can occur at initial application of line power.
2.5 Samples per second
±0.4%FS ±3 Counts with 60Hz
Sine-Wave Input
Accuracy €
Measurement Type
 The overcurrent rating of 1.5 x the rated full-scale current is a continuous rating
and applies to the current passing through the built in current transformer only,
it does not apply to any external circuit-wiring or external loads. Accuracy is
guaranteed up to the rated current level.
Model dependent, see page 3 & 4
Ordering Information
ACA-20RM- 1 - AC3 - R L - C
Add -C for RoHS
LED Color:
RL = Low-Power Red
Input Range:
Power:
AC3 = [email protected]/60Hz
0 = 199.9mA
AC4 = [email protected]/60Hz
1 = 1.999A
2 = 19.99A
4 = 50.0A (with split-core flying-lead CT)
5 = 30.0A (with flying-lead CT)
Accessories:
DMS-20-CP Panel Cutout Punch
TECHNICAL NOTES
IMPORTANT! To ensure safe and reliable operation, ACA-20RM
ammeters must be installed and serviced by qualified technical
personnel after reading this data sheet in it's entirety. Contact DATEL
if there is any doubt regarding their installation or
operation.
1. Measurement Type: ACA-20RM ac ammeters employ true-rms
input circuitry to measure the stepped-down output of their on-board
current transformers (CT). Stated accuracy is measured using a sinewave input at, or close to, the specified full scale input, at a nominal
line frequency of 60HZ.
2. Calibration: Periodic recalibration of ACA-20RM ammeters is not
required under normal indoor environments. If user calibration is
deemed necessary, it must be performed by qualified technical
personnel since potentially lethal voltages and currents are applied to
the ACA-20RM during the calibration process.
Weight
ACA-20RM-0,1,2-XXX-XX
1.1 ounces (31 grams) nominal
ACA-20RM-4-XXX-XX
2.1 ounces (60 grams) nominal
ACA-20RM-5-XXX-XX
1.5 ounces (43 grams) nominal
www.murata-ps.com
Calibration is performed with approximately 95% of the specified
full-scale current flowing through the ammeter’s built-in CT. A fully
insulated, non-metallic adjusting tool must be used to adjust the
calibration potentiometer, located on the back of the ammeter (see
Mechanical Specifications section).
Technical enquiries email: [email protected], tel: +1 508 339 3000
MPM_ACA-20RM_B02 Page 2 of 5
ACA-20RM Series
True-RMS-AC Ammeters with Built-in CT
The calibration potentiometer has approximately ¾ of a turn of rotation;
do not force its adjustment screw past the end stops. Contact MPS if
additional information is required regarding calibration, setup, or any
other technical issue pertaining to ACA-20RM ac ammeters.
3. Wire Gauges and Fusing: Use only the wires specified under the
Functional Specifications Section when making connections to ACA20RM Series ammeters. All power supply and load wiring must be
adequately rated for the supply voltages and currents they will carry,
and they must comply with all code- or application-mandated requirements pertaining to the user’s installation.
The supply wires connected to ACA-20RM ammeters must be fused
in accordance with applicable regulatory codes. Also, wire insulation should be stripped to within +/-10% of the stated dimensions;
wires should be inserted into TB1 such that the screw terminal does
not pinch their insulation. TB1 can only used for supplying power to
the meter’s internal circuitry; it must not be used to supply current to
external loads.
AC-powered models draw minimal steady-state supply currents (less
than 0.050A) and they can be fused according to the supply wire’s
maximum amperage rating. However, these models can draw higher
surge currents for brief periods (in the microsecond range) when power
is initially applied.
4. AC Supply Polarity and Grounding: The two supply inputs, TB1
‘A’ and ‘B’, on ACA-20RM ammeters are not polarity sensitive, that
is, they have no ‘AC LO’ or ‘AC HI’ designations. Also, ac-powered
ACA-20RM ammeters do not include or require a connection to earth/
chassis ground.
5. Connector Torque Ratings: Be sure to tighten TB1’s screw-terminals
to 3.6 pound-inches (0.4Nm). Proper tightening will ensure reliable
long-term operation.
6. Isolation: The on-board CT (L1) provides a minimum of 2000Vdc isolation between the current-carrying load conductor passing through
its opening and the ammeter’s power source that’s connected to TB1.
Of course, this isolation rating applies only to applications where the
load wire does not connect directly or indirectly to TB1-A or TB1-B
(i.e., where two different ac supplies are involved).
7. Split-Core CT (Clamp-on) Models: 50A models feature a split-core
current transformer that can be clamped around a current-carrying
load conductor without having to disconnect or remove power from
the load’s power source. This live-connection capability can only
be used if the load’s power source is isolated (see technical note 6)
from the ammeter’s own power source that’s connected to TB1.
The ammeter’s ac power supply must always be denergized before
making connections to TB1. Refer to the ‘Panel Installation’ section of
this data sheet for additional information.
WIRING DIAGRAMS
First pass and carefully dress one external load wire through L1, then
connect the AC supply and load wires to TB1 as shown. Ensure all wires
are stripped and properly tightened. For accurate operation, make only
one pass with load wire through the on-board CT (only one primary turn).
For split-core CT models, make sure to fully engage the CT's Locking
mechanism
BACK VIEW
BACK VIEW
A
A
FUSED AC POWER
TB1
FUSED AC POWER
B
TB1
B
TO AC LOAD
L1
L1
TO AC LOAD
FROM AC SUPPLY
Figure 2. Connections for pc-board mounted CT's
FROM AC SUPPLY
Figure 3. Connection for flying lead CT's
www.murata-ps.com
Technical enquiries email: [email protected], tel: +1 508 339 3000
MPM_ACA-20RM_B02 Page 3 of 5
ACA-20RM Series
True-RMS-AC Ammeters with Built-in CT
PANEL INSTALLATIONS
All connections to ACA-20RM Series ammeters must be made after the
ammeter is securely attached to its panel and with all associated load
and supply voltages de-energized (off). However, using extreme caution
and observing all safety measures applicable to the user’s installation,
50A split-core CT models can be connected to energized current-carrying load conductors, but connections to TB1 must always be made with
the ammeter’s power source off.
Using Figure 4 as a guide, carefully insert the bezel/color filter assembly
into the panel opening. From the rear of the panel, install the four round
plastic standoffs over the bezel’s threaded studs. Install the pc-board
assembly then attach and securely tighten all four hex nuts. Use only
the factory-supplied hardware as the use of substitute hardware could
result in an unsafe installation and/or adversely affect the reliability of
the ammeter itself.
The recommended range of panel thickness that can be used with the
supplied hardware is 0.040 inches (1.0mm) to 0.125 inches (3.2mm).
Panel thickness outside of this range will require additional user-supplied
hardware and/or modifications.
Care should be exercised when passing the load-carrying conductor
through the meter’s built-in CT---particularly when larger conductors are
used. The installed wire-positions should be such that minimal mechanical forces are applied to the built-in CT, TB1, or to the ammeter itself. In
high-vibration environments, it is strongly recommended that adequate
strain reliefs be used for all load and supply wiring.
PANEL
3TANDOFF
'ASKET
4HICK
'ASKET
.UT
3TANDOFF
"OARD #UTOUT
"EZEL
!#! 2!# !MMETER
3)$% 6)%7
Figure 4. Panel Installation
BEZEL AND PANEL CUTOUT
RECOMMENDED DRILL AND
PANEL CUTOUT DIMENSIONS
0.187
(4.75)
0.55
(13.97)
FRONT VIEW
1.280
(32.51)
INTERNAL CORNER RADII:
0.032 (0.81) MAX.
1.07
(27.18)
0.116 (2.95)
0.838
(21.29)
1.336 (33.93)
0.145 (3.68)
1.826 (46.38)
1.626 (41.30)
0.093 (2.362) DIAMETER (4 REQUIRED)
www.murata-ps.com
Technical enquiries email: [email protected], tel: +1 508 339 3000
MPM_ACA-20RM_B02 Page 4 of 5
ACA-20RM Series
True-RMS-AC Ammeters with Built-in CT
MECHANICAL SPECIFICATIONS
,%!$%$ 30,)4 #/2% #4 -/$%,3
&2/.4 6)%7
,%!$%$ #4 -/$%,3
&2/.4 6)%7
2.100
(53.34)
2.100
(53.34)
-
-
-
0# "/!2$ -/5.4%$ #4 -/$%,3
&2/.4 6)%7
2.100
(53.34)
-
-
-
1.400
(35.56)
1.400
(35.56)
1.750
(44.45)
"!#+ 6)%7
"!#+ 6)%7
"!#+ 6)%7
CAL
TB1
Lead Length
5.0 (127.0) min.
L1
Lead Length
2.0 (50.5) min.
0.35
(8.9)
Diameter
1.575
(40.00)
0.40
(10.2)
Diameter
3)$% 6)%7
3)$% 6)%7
0.26 (6.6)
Diameter
0.984
(24.99)
3)$% 6)%7
0.250
(6.35)
1.024
(26.01)
0.250
(6.35)
0.250
(6.35)
0.480
(12.19)
0.551
(14.00)
1.00 (2.54)
For 2A and 20A
Models
MECHANICAL DIMENSIONS: Inches (mm)
TOLERANCES:
2 PL DEC ±0.02 (±0.51)
3 PL DEC ±0.010 (±0.254)
0.480
(12.19)
USA:
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A.
Tel: (508) 339-3000 (800) 233-2765 Fax: (508) 339-6356
www.murata-ps.com email: [email protected] ISO 9001 and 14001 REGISTERED
12/23/08
Murata Power Solutions, Inc. 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. Specifications are subject to change without
notice.
© 2008 Murata Power Solutions, Inc.
www.murata-ps.com
Mansfield (MA), Tel: (508) 339-3000, email: [email protected]
Canada:
Toronto, Tel: (866) 740-1232, email: [email protected]
UK:
Milton Keynes, Tel: +44 (0)1908 615232, email: [email protected]
France:
Montigny Le Bretonneux, Tel: +33 (0)1 34 60 01 01, email: [email protected]
Germany:
München, Tel: +49 (0)89-544334-0, email: [email protected]
Japan:
Tokyo, Tel: 3-3779-1031, email: [email protected]
Osaka, Tel: 6-6354-2025, email: [email protected]
China:
Shanghai, Tel: +86 215 027 3678, email: [email protected]
Guangzhou, Tel: +86 208 221 8066, email: [email protected]
Singapore:
Parkway Centre, Tel: +65 6348 9096, email: [email protected]
Technical enquiries email: [email protected], tel: +1 508 339 3000
MPM_ACA-20RM_B02 Page 5 of 5
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