ACI ECMCS25-A ECM Adjustable Trip Point Current Switch
An adjustable current switch lets the installer set the trip threshold in the field, which is what makes it suitable for condition monitoring rather than simple on/off proof. Because the ECMCS25-A trip point can be placed between the loaded and unloaded current of a driven load, it can distinguish a motor that is running normally from one that is running but has lost its belt, is slipping, has a locked rotor, or is otherwise running under- or over-loaded. ACI lists overload, underload, broken belt, belt slippage, locked rotor and equipment failure as the supported applications for adjustable current switches.
The split-core housing opens around an existing conductor, so the ECMCS25-A can be fitted to wiring that is already terminated. ACI directs that the switch be installed on the line side of the power feeding the monitored equipment, and that all power sources be disconnected and locked out before the device is installed. That is what makes split-core the standard choice for retrofit work and for service vehicles, where one part covers most jobs.
Electronically commutated motors draw a small standby current whenever they are powered but not spinning, unlike a PSC motor which draws nothing at rest. A conventional current switch will read that standby draw as a running motor. The ECMCS25-A has a trip range of 0.075 to 0.5 A specifically so the threshold can be set above the standby current and below the running current. ACI publishes a separate TRIP ADJUST TOOL (item # 149977) that gives a visual indication of output state during commissioning.
Specifications on this page are taken from the ACI ECMCS Current Switch data sheet.
Best For
- Belt-loss, belt-slip and locked-rotor detection where the trip point must sit between loaded and unloaded current
- Preventative maintenance scheduling driven by measured load change
- Motor, pump, fan and compressor run status feedback to a BMS, PLC or DDC controller
- Proof-of-operation and run-status interlocks on air handlers and hydronic equipment
- Runtime accumulation and basic load trending from dry-contact closures
- Lighting circuit status and usage logging
Warranty
Key Features
Field-Adjustable Trip Point
Trip threshold is set in the field anywhere from 0.075 to 0.5 A, with 10% hysteresis typical, so the switch can be tuned to the actual load rather than a factory default.
Self-Powered by Induction
Power is induced from the monitored conductor. There is no 24 V supply to run, no transformer to size and no separate power wiring to install.
Split-Core Aperture
Opens around an existing conductor for retrofit installation without disconnecting any wiring.
Normally-Open (N/O) Dry Contact
Rated 0.1 A (100 mA) continuous @ 30 VAC/VDC, wired to a 2-position screw terminal block that is not polarity sensitive. Contact resistance is under 10 Ohms tripped and over 1 Meg Ohm open.
Built for ECM Standby Current
The 0.075 to 0.5 A trip range sits between the standby draw of a powered ECM and its running current, which a conventional current switch cannot resolve.
Calibration Tool Available
ACI item # 149977 TRIP ADJUST TOOL gives a visual indication of output switch state during commissioning, ordered separately.
Technical Specifications
| ACI Item Number | 149979 |
| Core Style | Split-Core |
| Trip Point Style | Adjustable Trip Point |
| Trip Point | 0.075 to 0.5 A |
| Amperage Range | 0 to 25 A |
| Contact Type | Normally-Open (N/O) |
| Contact Rating | 0.1 A (100 mA) continuous @ 30 VAC/VDC |
| Hysteresis | 10% of trip point, typical |
| Operating Frequency Range | 50/60 Hz |
| Monitored Current Type | AC Current |
| Maximum AC Voltage | 600 VAC |
| Isolation Voltage | 600 VAC |
| Sensor Power | Induced from the monitored conductor (insulated conductors only) |
| Response Time | < 5 seconds typical |
| Contact On Resistance | Off Resistance | < 10 Ohms (tripped) | > 1 Meg Ohm (open) |
| 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 Temperature Range | 32 to 140 °F (0 to 60 °C) |
| Operating Humidity Range | 10 to 90% RH, non-condensing |
| Recommended Storage Temperature | RH | -40 to 158 °F (-40 to 70 °C) | 10 to 90% RH, non-condensing |
| Enclosure Material | Flammability Rating | PC/ABS (polycarbonate / ABS blend) | UL94-V0 |
| Wiring Connections | 2-position screw terminal block (not 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 |
| Application Limitation | Not intended to monitor status in VFD motor applications |
| Agency Approvals | UL/CUL US Listed (UL 916) Energy Management Equipment, File # E334792, CE, UKCA, RoHS, WEEE, CAN ICES-3 / NMB-3 |
| 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 | 0.14 lbs (0.065 kg) |
| Warranty | Five (5) Year Limited Warranty |
Not intended for use in life / safety applications or in hazardous / classified locations.
Documentation
ACI ECMCS Current Switch Data SheetRelated Products
Frequently Asked Questions
What is the trip point of the ACI ECMCS25-A?
The ECMCS25-A trip point is 0.075 to 0.5 A. It is adjustable in the field over that range, with 10% hysteresis typical.
Does the ACI ECMCS25-A need external power?
No. Power is induced from the conductor being monitored, so no 24 VAC or 24 VDC supply, transformer or power wiring is required. The two terminals carry the dry contact output only.
Is the ACI ECMCS25-A solid-core or split-core?
The ECMCS25-A is split-core. Split-core units open around an existing conductor and install without disconnecting any wiring, which is why they are used in retrofit work.
What is the contact rating of the ACI ECMCS25-A?
The status contact is Normally-Open (N/O) rated 0.1 A (100 mA) continuous @ 30 VAC/VDC. Contact resistance is under 10 Ohms when tripped and over 1 Meg Ohm when open.
Can the ECMCS25-A be used on a VFD-driven motor?
No. ACI states the ECM switch is not intended to monitor status in VFD motor applications. It is designed for the standby-current profile of electronically commutated motors.
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
- Setpoint:
- Adjustable Trip
- Contact Type:
- Normally Open
- Amp Range:
- 0-25A
- Trip Point:
- 0.075-0.5A
- Contact Rating:
- 0.1 A (100 mA) @ 30 VAC/VDC
- Contact Termination:
- Terminal Strip
- Sensor Power:
- Self-Powered
- Motor Type:
- ECM
- Warranty:
- 5-Year Limited
