ACA-20RM-ALM Datasheet, PDF (2/5 Pages) Murata Power Solutions Inc. – True-rms-AC Ammeters with Alarm Function

ACA-20RM-ALM Series
True-rms-AC Ammeters with Alarm Function
Performance/Functional Specifications
Typical at TA = +25°C, unless otherwise noted.
Rated Full-Scale Current ~
ACA-20RM-4-ACX-RL-ALM
ACA-20RM-5-ACX-RL-ALM
Overcurrent Rating 
Performance
Sampling Rate
Accuracy €
Measurement Type
Temperature Drift (0 to 60 °C)
Zero-Current Reading (within
30 sec.)
Dielectric Withstanding Voltage
Power Supply Voltage
ACA-20RM-X-AC3-RL-ALM
ACA-20RM-X-AC4-RL-ALM
Power Supply Current 
ACA-20RM-X-AC3-RL-ALM
ACA-20RM-X-AC4-RL-ALM
Alarm Function
Display indication
Settable range
ACA-20RM-4-ACX-RL-ALM
ACA-20RM-5-ACX-RL-ALM
Power Supply Terminal Block
Wire Size
Insulation Strip Length
Screw Tightening Torque
Rated Voltage
Display
Display Type and Size
Overrange Indication
Decimal Point
Physical/Environmental
Operating Temperature
Storage Temperature
Humidity (non-condensing)
Dimensions
Weight
ACA-20RM-4-XXX-XX-ALM
ACA-20RM-5-XXX-XX-ALM
Min. Typ. Max.
Units
— — 50.0 Amperes
— — 30.0 Amperes
1.5 x Rated Full-Scale Current
2.5 Samples per second
±0.4%FS ±3 Counts with 60Hz
Sine-Wave Input
rms Responding, Crest Factors of 1-5
— ±0.2 ±0.4 Counts/ºC
–001 000 001
Counts
2000 — —
Vdc
85 120
170 220
140 Vac/47-63Hz
264 Vac/47-63Hz
— 30
— 30
50 mA/47-63Hz
50 mA/47-63Hz
Flashing Display with actual current
reading and display intensity change
13 45 50
8 24 30
Amps
Amps
16-22AWG, Solid or stranded
0.250 inches
3.6 pounds-inches (0.4Nm)
310Vac
3½ Digit Red LED, 0.37”/9.4mm High
“1___”
Fixed, model dependent
(see full-scale input current)
0 — +60
°C
–40 — +75
°C
0 — 85
%
Model dependent, see page 4 & 5
1.5 Ounces (43 grams) nominal
2.1 Ounces (60 grams) nominal
~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 ad-
ditional model-specific information.
 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.
€ 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.
Ordering Information
ACA-20RM-4-AC3-RL-ALM-C
ACA-20RM-4-AC4-RL-ALM-C
ACA-20RM-5-AC3-RL-ALM-C
ACA-20RM-5-AC4-RL-ALM-C
50.0A Range (split-core CT), 85-140Vac power
50.0A Range (split core CT), 170-264Vac power
30.0A Range, 85-140Vac power
30.0A Range, 170-264Vac power
TECHNICAL NOTES
IMPORTANT! To ensure safe and reliable operation, ACA-20RM-
ALM ammeters must be installed and serviced by qualified
technical personnel. Contact Murata Power Solutions if there is
any doubt regarding ammeter setup, installation, or operation.
1. Measurement Type: ACA-20RM-ALM ac ammeters employ a
true-rms input circuit to measure current flowing through L1. Stated
accuracy specifications are measured using a sine-wave current
at, or close to, the ammeter’s full-scale input range, at nominal line
frequency of 60Hz.
2. Calibration (Potentiometer R7): Periodic recalibration of ACA-
20RM-ALM ammeters is not required under normal, indoor operating
environments. If user calibration is necessary, it must be performed
by qualified technical personnel. Calibration is performed with poten-
tially lethal voltages applied to the ACA-20RM-ALM and its associated
wiring. A plastic, fully-insulated adjusting tool must be used to access
the calibration potentiometer R7 located on the back of the ammeter
(see ‘Mechanical Specifications’ section). Contact MPS if additional
information is required regarding calibration, setup, or any other
technical issue pertaining to ACA-20RM-ALM ammeters.
3. Overcurrent Alarm Setup and Adjustment (Potentiometer R3):
ACA-20RM-ALM ammeters feature a user-settable, overcurrent visual
alarm indication which can be used to alert operators that a load cir-
cuit breaker or fuse is approaching an overload condition. When the
load current sensed by L1 exceeds this preset level, the ammeter’s
LED display will flash from normal intensity to dim intensity at rate of
approximately 1.5 times per second.
As shown in Figure 3, the alarm circuit consists of jumper JP1, and
adjustment potentiometer R3. As shipped, R3 is factory set to trip
when the load current is approximately 24 Amps for 30A models, and
approximately 45 Amps for 50A models. When R3 is set to its maxi-
mum clockwise position, the alarm indication will not activate until the
load current flowing through L1 exceeds the maximum rating of the
ammeter, i.e., above 30.0A, or above 50.0A, depending on the model.
www.murata-ps.com
Technical enquiries email: [e-mail], tel: [phone]
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