New head-mount thermocouple transmitter

An enhanced version of USB-configured thermocouple/millivolt input transmitters with an isolation barrier to protect from surges, reduce noise, and eliminate ground loop errors.

The latest release in Acromag’s new ST130 series of low-cost, temperature transmitters is the Model ST133, an isolated thermocouple/millivolt signal conditioner. This high-performance version of the economy-level ST132 also converts sensor input signals from eight thermocouple types or a ±100mV range and outputs a proportional 4-20mA process control signal. However, the addition of 1500V isolation between the input and output circuit shields equipment from high-voltage surges and transient signals. The isolation also breaks up ground loops and reduces signal noise that could interfere with measurement accuracy. Installing this output loop-powered two-wire transmitter is easy and a USB connection to your PC simplifies set up using free Windows configuration software. Units support mounting in DIN Form B sensor heads or on a DIN rail. They are CE compliant with pending UL/cUL Class 1


“With the new ST133 thermocouple transmitter we can now offer a choice of isolated or non-isolated units to better meet a customer’s price/performance requirements,” says Don Lupo, Acromag’s sales and marketing director. Many end-user and OEM applications still require high isolation to combat and reject the effects of large common mode voltages, electrical noise, surges, and system ground loops. The ST133 bridges the gap between economy units and more expensive high-performance isolated transmitters.

Other features include signal linearization and cold-junction compensation functions. Response times are as low as 30ms. The Windows software helps you quickly configure the transmitter using a USB cable connection to select input type with standard or reverse-acting output, scale I/O ranges, set filtering levels, and choose upscale or downscale operation for sensor faults. Digital calibration eliminates zero/span pots, DIP switches, and pushbuttons for more precise and stable measurements.

A rugged design helps these transmitters operate reliably in harsh industrial environments. Ambient temperature drift is less than 75ppm/°C for long-term stability. The ST133 is shock (50g) and vibration (5g) resistant and includes high-level electrical noise immunity (RFI, EMI, ESD, EFT, and surge protection). And to prevent incorrect wiring, the output/power connection is non-polarized.

For easy installation, Acromag sells a variety of mounting and wiring accessories. A USB isolator further protects equipment from ground loops, electrical noise, and surges during configuration. For convenience, a kit supplies the software, isolator, and USB interface cables. Numerous connection head enclosures are also available from Acromag. Select from stainless steel, aluminum, and cast iron housings with explosion-proof or general-purpose ratings. A DIN rail adapter offers alternative mounting options.

Acromag has designed and manufactured measurement and control products for more than 50 years. They are an AS9100 and ISO 9001-certified international corporation with a world headquarters near Detroit, Michigan and a global network of sales representatives and distributors. Acromag offers a complete line of industrial I/O products including a variety of process instruments, signal conditioners, and distributed fieldbus I/O modules that are available with a 7-year warranty. Industries served include chemical processing, manufacturing, defense, energy, and water services.