MTT MS3003 Terminal Block Type Millivolt Isolator

We had an enquiry from a customer running a weighing system on their production line. The load cell output was only a few millivolts, and the reading at the control room kept drifting depending on which cable route it took through the plant. They wanted to know if there is a way to clean up the millivolt signal before it reaches the PLC.

This looks simple, but millivolt signals are actually one of the most fragile signal types to wire on an industrial site. At that level, even a small amount of electrical noise from a VSD, a welding set, or just a long cable run can swamp the real signal. Ground loops between the sensor and the control panel add further error on top of that. Converting to a stronger, standard signal as close to the source as possible is far more reliable than trying to fix the reading downstream.

For this, we would normally recommend the MTT MS3003, a terminal block type millivolt isolator. It takes a low millivolt input, down to a 5mV span, and converts it into a standard 4 to 20mA current or DC voltage output, fully isolated between input, output, and power supply. Because it is isolated, it breaks the ground loop and rejects common-mode noise picked up along the cable run. It mounts on DIN rail, so it can sit right in the junction box near the load cell or sensor, and it has field-adjustable zero and span so technicians can calibrate it on site without pulling the unit out of service.

Before we quote, we would normally check the exact millivolt span from the customer’s sensor, the output signal their PLC or DCS expects, and the supply voltage available at the panel, since the MS3003 comes in both 24V DC and 12V DC versions. Hope this helps — feel free to reach out with your site details and we can confirm the right model together.