ACI A/SCTA2-50 4 to 20 mA Output Analog Current Sensor
The A/SCTA2-50 uses averaging measurement, which assumes a pure sinusoidal waveform with little or no distortion on the monitored conductor. It is the correct and lower-cost choice for resistive and single-speed linear loads such as incandescent lighting, heating elements and across-the-line motors. Where the load is fed by a VFD or a switching supply, ACI directs users to the True RMS A/CTA2-RMS or A/SCTA2-RMS series instead.
Amperage range is field selectable across 0 to 10 / 20 / 50 A, so a single part number covers three spans and stock can be consolidated. Selecting the narrowest range that contains the expected load gives the best resolution, because accuracy is specified as a percentage of the selected range rather than of the maximum.
The output is a 2-wire, loop-powered 4 to 20 mA signal, which needs an external +8.5 to 30 VDC supply. ACI specifies a maximum run of 30 m (98.4 ft) of 2-conductor shielded cable between the sensor and the building management system. Where the controller input expects a voltage signal, ACI publishes 249 Ohm and 499 Ohm precision resistors that convert the loop to 1 to 5 VDC or 2 to 10 VDC at the panel.
The split-core housing opens around an existing conductor, so the A/SCTA2-50 can be fitted to wiring that is already terminated. All power sources must be disconnected and locked out before installation. That makes it the practical choice for retrofit and service work.
Specifications on this page are taken from the ACI 4 mA to 20 mA Output Current Sensor Series data sheet Version 2.0 and User's Manual I0000789 Rev. 10.0.
Best For
- Load trending and basic power monitoring on single-speed linear loads
- LEED documentation and energy project ROI justification
- Continuous amperage feedback to a BMS, PLC or DDC analog input
- Preventative maintenance programs that need measured current, not just on/off status
Warranty
Key Features
Average Measurement
Averaging measurement for pure sinusoidal waveforms. Correct and cost-effective on resistive and single-speed linear loads.
Field-Selectable Ranges
One part number covers 0 to 10 / 20 / 50 A. Pick the narrowest span that contains the expected load for the best resolution.
4 to 20 mA (2-wire, loop powered) Output
Loop-powered 2-wire signal on 2-conductor shielded cable, up to the 30 m (98.4 ft) run ACI specifies. Optional 249 Ohm and 499 Ohm resistors convert to 1 to 5 VDC or 2 to 10 VDC at the panel.
Split-Core Aperture
Opens around an existing conductor for retrofit installation without disconnecting any wiring.
Published Accuracy
+/- 1% of selected range. All current output sensors are calibrated at an ambient room temperature of 71 °F (21.5 °C).
Patented DIN Rail Mounting Foot
Snaps onto 35 mm DIN rail for panel installation. U.S. Patent No. 7,416,421.
Technical Specifications
| ACI Item Number | 142375 |
| Core Style | Split-Core |
| Selectable Amperage Ranges | 0 to 10 / 20 / 50 A |
| Measurement Method | Average |
| AC Waveform | Pure Sinusoidal |
| Output Signal | 4 to 20 mA (2-wire, loop powered) |
| Accuracy | +/- 1% of selected range |
| Operating Frequency Range | 40 Hz to 1000 Hz |
| Response Time | < 600 mS (rise and fall time) |
| Monitored Current Type | AC Current |
| Maximum AC Voltage | 600 VAC |
| Isolation Voltage | 2200 VAC |
| Supply Voltage | +8.5 to 30 VDC (reverse polarity protected); 250 Ohm load (1 to 5 VDC): +13.5 to 30 VDC; 500 Ohm load (2 to 10 VDC): +18.5 to 30 VDC |
| Supply Current | 25 mA minimum |
| Maximum Load Resistance @ 24 VDC | 775 Ohms (formula: (24 VDC - 8.5 VDC) / 0.020 A) |
| Output Signal | Maximum Output | 4 to 20 mA (2-wire, loop powered) | limited to 25 mA |
| Aperture Size | 0.75 in (19.05 mm) |
| DIN Rail Size | 35 mm (U.S. Patent No. 7,416,421) |
| Operating Temperature Range | 5 to 104 °F (-15 to 40 °C) |
| Operating Humidity Range | 0 to 95% RH, non-condensing |
| Storage Temperature | RH Range | 41 to 95 °F (5 to 35 °C) | 40 to 85% RH, non-condensing |
| Enclosure Material | Flammability Rating | PC/ABS (polycarbonate / ABS blend) | UL94-V0 |
| Wiring Connections | 2-position screw terminal block (polarity sensitive) |
| Wire Recommendations | 2-conductor shielded cable |
| Wire Size | 18 to 24 AWG (0.823 mm2 to 0.205 mm2), copper wires only |
| Terminal Block Torque Rating | 4.43 to 5.31 in-lbs (0.5 to 0.6 Nm) |
| Minimum Mounting Distance | 1 in (2.6 cm) from relays, contactors and transformers |
| Calibration Reference | All current output sensors are calibrated at an ambient room temperature of 71 °F (21.5 °C) |
| Agency Approvals | UL/CUL US Listed (UL 508) Industrial Control Equipment, File # E309723, RoHS2, WEEE, UKCA; -RMS versions CE to IEC 61326-1:2012 Class A |
| Product Dimensions (L x W x H) | 2.780 in (70.51 mm) x 3.238 in (82.25 mm) x 1.120 in (28.45 mm) |
| Product Weight | 0.274 lbs (0.124 kg) |
| Warranty | Five (5) Year Limited Warranty |
Not intended for use in life / safety applications or in hazardous / classified locations.
Range Selection and Commissioning
All models with selectable amperage ranges ship with the range selection jumper factory set on the high range; set the jumper to the correct range at commissioning. The selected range is the maximum current that may be applied to the monitored conductor and must not be exceeded. An extra jumper shunt is supplied and may be discarded if not needed; in high-vibration installations ACI recommends using the jumper shunt without the tab.
Output Conversion Resistors (ordered separately)
| ACI Item # | Description |
|---|---|
| 100307 | 249 Ohm, 1/4 W, +/- 1% tolerance, 50 ppm resistor (converts output to 1 to 5 VDC) |
| 100306 | 249 Ohm, 1/4 W, +/- 0.1% tolerance, 50 ppm resistor, recommended for best accuracy (converts output to 1 to 5 VDC) |
| 100469 | 499 Ohm, 1 W, +/- 1% tolerance, 50 ppm resistor (converts output to 2 to 10 VDC) |
Documentation
ACI 4 mA to 20 mA Output Current Sensor Series Data Sheet (Version 2.0)ACI 4 mA to 20 mA Output Current Sensor Series User's Manual (I0000789 Rev. 10.0)Related Products
Frequently Asked Questions
What output signal does the ACI A/SCTA2-50 produce?
The A/SCTA2-50 produces a 4 to 20 mA (2-wire, loop powered) signal. It is loop powered and needs an external +8.5 to 30 VDC supply.
What amperage ranges does the ACI A/SCTA2-50 cover?
The A/SCTA2-50 covers 0 to 10 / 20 / 50 A, selectable in the field. Accuracy is specified as a percentage of the selected range, so choosing the narrowest range that contains the expected load gives the best resolution.
Can the ACI A/SCTA2-50 be used downstream of a variable frequency drive?
No. This sensor uses averaging measurement, which assumes a pure sinusoidal waveform. For VFDs, switching power supplies and other distorted waveforms, ACI directs users to the True RMS A/CTA2-RMS or A/SCTA2-RMS series.
What is the published accuracy of the ACI A/SCTA2-50?
+/- 1% of selected range. All ACI current output sensors are calibrated at an ambient room temperature of 71 °F (21.5 °C).
How is the ACI A/SCTA2-50 converted to a voltage signal?
ACI publishes precision resistors for this: item # 100307 or # 100306 (249 Ohm) convert the loop to 1 to 5 VDC, and item # 100469 (499 Ohm, 1 W) converts it to 2 to 10 VDC. The resistor is ordered separately and installed at the controller input.
ACI Five (5) Year Limited Warranty. This product is covered by Automation Components, Inc.’s Five (5) Year Limited Warranty, published in the front of the ACI Sensors & Transmitters catalog and on the ACI website. Warranty terms are set by the manufacturer and are subject to change without notice.
- Mounting Type:
- Split-Core
- Selectable Range:
- 0-10/20/50A
- Output Signal:
- 4-20 mA
- Measurement:
- Average
- AC Waveform:
- Pure Sinusoidal
- Sensor Power:
- Loop Powered
- Warranty:
- 5-Year Limited
