The MTT MS3720 is a slim plug-in CT transmitter that reads the AC current output of a current transformer, calculates its true RMS value, and converts it into a standard DC signal that displays, controllers, and data acquisition systems can work with. It is the go-to way to bring motor, feeder, or panel current readings into a monitoring system without exposing that equipment to the high current itself, since the CT keeps the sensed circuit electrically separate.
Both 1A and 5A CT input ranges are available, and current or voltage output options let it match the receiving equipment, with a second isolated output for feeding an independent monitoring or alarm system at the same time. Like the rest of the plug-in transmitter series, the MS3720 clips into its own socket base for fast swap-out during calibration or maintenance without disturbing the field wiring, and flexible AC or DC power plus wall or DIN rail mounting make it easy to fit into an existing panel.
| Input Range | 0-1A AC or 0-5A AC, 50/60Hz |
| Input Resistance | 10mΩ (1A) or 2mΩ (5A) shunt resistor |
| Allowable Current | 120% rated input continuous; up to 10× rated instantaneous (within 3 seconds) |
| Crest Factor | 3 max. |
| Output | 0-20mA or 4-20mA DC current; 10mV to 20V DC voltage; single or dual isolated output |
| Output Load | 750Ω max. (4-20mA single); 550Ω/350Ω max. (dual) |
| Adjustments | ±5% span, front-panel trimmers |
| Accuracy | Better than ±0.25% of span (10%+ input, at 25°C±5°C) |
| Temperature Effect | ±0.2% of span per 10°C change |
| Response Time | 400ms max. (0-90%, step input at 100%) |
| CMRR | 100dB min. (500V AC, 50/60Hz) |
| Isolation | 4-way isolation between input, output 1, output 2, and power |
| Insulation Resistance | 100MΩ min. at 500V DC |
| Power Supply | 100-240V AC (47-63Hz), 24V DC (±10%), or 100-240V DC |
| Power Consumption | 1.2-4.8W (single output); 1.6-6.0W (dual output) |
| Dimensions | W29 × H86 × D125mm (excl. shunt resistor) |
| Weight | 120g max. (main unit), plus 80g max. socket, 5g max. resistor |
| Mounting | Wall or DIN rail mounting |
| Terminals | M3.5 screw terminals, 0.8-1.0 Nm torque |
| Operating Temperature | -5 to 55°C |
| Operating Humidity | 5 to 90% RH, non-condensing |
Frequently Asked Questions
What is the MTT MS3720 used for?
It reads the AC output of a current transformer (CT), calculates the true RMS current, and converts it into a standard DC signal for your display, controller, or data acquisition system — a common way to bring motor, feeder, or panel current readings into a monitoring system safely.
What CT input ranges does the MS3720 support?
Both 1A and 5A CT secondary ranges are available. Tell us your CT’s secondary rating and we can confirm the right input range at order.
Does the MS3720 provide electrical isolation from the CT circuit?
Yes — the output is isolated from the input, so your monitoring system is electrically separated from the current transformer circuit.
Can the MS3720 provide two separate outputs?
Yes — a second isolated output is available, so the current reading can feed a controller and a separate monitoring or alarm system at the same time.
How do I know if the MS3720 is the right model for my application?
Send us your CT’s secondary current rating and the output signal your receiving equipment expects, and we can confirm before you order.
Download MTT MS3720 Slim Plug-In CT Transmitter information here
Spec Sheet: SpecSheet1_MS3720_Rev310_E.pdf
Manual: Manual1_MS3720_Rev190_E.pdf
