ACI A/MSCTA-40 Mini Analog Current Sensor
The A/MSCTA-40 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.
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/MSCTA-40 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 MSCTA-40 & MSCTE-40 Series data sheet and User's Guide I0000984.
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.
Fixed 0 to 40 A Range
A single 0 to 40 A sensor amperage range with no jumper to set, and accuracy specified across the full range rather than a selected sub-range.
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
+/- 0.75% FS (+/- 0.3 A) above 2 A. All current output sensors are calibrated at an ambient room temperature of 71 °F (21.5 °C).
Cable Tie Anchor and Mounting Foot
Secures to the monitored cable with a cable tie, or mounts with the attachable foot using one Tek screw or directly on 35 mm DIN rail.
Technical Specifications
| ACI Item Number | 151890 |
| Core Style | Split-Core |
| Sensor Amperage Range | 0 to 40 A |
| Measurement Method | Average |
| AC Waveform | Pure Sinusoidal |
| Output Signal | 4 to 20 mA (2-wire, loop powered) |
| Accuracy | +/- 0.75% FS (+/- 0.3 A) above 2 A |
| 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 | 775 Ohms @ 24 VDC |
| Response Time | < 600 mS (rise and fall times) |
| Operating Temperature Range | -22 to 140 °F (-30 to 60 °C) |
| Monitored Current Type | AC Current |
| Maximum AC Voltage | 600 VAC |
| Isolation Voltage | 2200 VAC |
| Operating Frequency Range | 50/60 Hz |
| Aperture Size | 0.20 in (5.0 mm) x 0.49 in (12.5 mm) |
| Monitored Wire Size | Fits 10 AWG to 14 AWG THHN insulated wire |
| DIN Rail Size | 35 mm |
| Operating Humidity Range | 10 to 95% RH, non-condensing |
| Storage Temperature | RH Range | -40 to 158 °F (-40 to 70 °C) | 10 to 95% RH, non-condensing |
| Enclosure Material | Flammability Rating | PC/ABS (polycarbonate / ABS blend) | UL94-V0 |
| Wiring Connections | 2-position screw terminal block (polarity sensitive) |
| Wire Size | 16 to 22 AWG (1.31 mm2 to 0.33 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 |
| Product Dimensions (L x W x H) | 1.93 in (48.99 mm) x 1.31 in (33.17 mm) x 2.18 in (55.37 mm) |
| Product Weight | 0.165 lbs (0.075 kg) |
| Agency Approvals | UL/CUL US Listed (UL 508) Industrial Control Equipment, File # E309723, CE, RoHS, UKCA, FCC, CAN ICES-3 / NMB-3 |
| Warranty | Five (5) Year Limited Warranty |
Not intended for use in life / safety applications or in hazardous / classified locations.
Accuracy Specifications
| Accuracy | Current | Operating Temperature | Frequency |
|---|---|---|---|
| +/- 0.75% FS (+/- 0.3 A) | Greater than 2 A | 5 to 140 °F (-15 to 60 °C) | 60 Hz |
| +/- 0.75% FS (+/- 0.3 A) | Greater than 2 A | 32 to 140 °F (0 to 60 °C) | 50 Hz |
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 MSCTA-40 & MSCTE-40 Series Analog Output Current Sensor Data SheetACI MSCTA-40 & MSCTE-40 Series Analog Output Current Sensor User's Guide (I0000984)Related Products
Frequently Asked Questions
What output signal does the ACI A/MSCTA-40 produce?
The A/MSCTA-40 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/MSCTA-40 cover?
The A/MSCTA-40 has a fixed sensor amperage range of 0 to 40 A.
Can the ACI A/MSCTA-40 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/MSCTA-40?
+/- 0.75% FS (+/- 0.3 A) above 2 A. All ACI current output sensors are calibrated at an ambient room temperature of 71 °F (21.5 °C).
How is the ACI A/MSCTA-40 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
- Amp Range:
- 0-40A
- Output Signal:
- 4-20 mA
- Measurement:
- Average
- AC Waveform:
- Pure Sinusoidal
- Sensor Power:
- Loop Powered
- Warranty:
- 5-Year Limited
