Description
The Acromag 651T-0600 is a high-performance, industrial-grade two-wire transmitter designed to convert thermocouple or millivolt input signals into a stable 4-20mA DC output. Part of the 650T series, this device is engineered for precision signal conditioning in rugged environments where isolation and accuracy are paramount.
Product Introduction
The 651T-0600 is an isolated transmitter that provides a professional solution for interfacing temperature sensors with control systems such as PLCs, DCS, or SCADA systems. It features a compact, “flat-pack” design that allows for high-density mounting on DIN rails.
A key characteristic of the 651T-0600 is its Input-to-Output Isolation, which protects sensitive control equipment from ground loops and electrical noise common in industrial motor control centers or plant floors. The unit is field-programmable, allowing users to select different thermocouple types and input ranges via internal switches and potentiometers for zero and span adjustment.
Acromag 651T-0600
Product Parameters (Datasheet)
The following specifications detail the technical and electrical characteristics of the 651T-0600:
| Parameter | Specification |
| Model Number | 651T-0600 |
| Input Type | Thermocouple (J, K, T, E, R, S, B) or Millivolt (±100mV) |
| Output Type | 4 to 20 mA DC (Two-wire loop powered) |
| Isolation | 1500V AC (Input-to-Output) |
| Accuracy | Better than ±0.1% of span |
| Ambient Temperature Drift | ±0.01% per °C (typical) |
| Power Requirement | 12 to 50V DC (Loop-powered) |
| Input Impedance | > 10 Megohms |
| Response Time | 100 milliseconds (typical) |
| Cold Junction Compensation | Automatic, referenced to 0°C |
| Operating Temperature | -25°C to +85°C (-13°F to +185°F) |
| Enclosure | Rugged Lexan, UL94 V-0 (Self-extinguishing) |
Country of Origin
- Origin: United States (USA)
Acromag products are designed and manufactured at their headquarters in Wixom, Michigan, USA. This ensures high standards of quality control and compliance with industrial certifications.
Technical Description & Key Features
The 651T-0600 utilizes advanced analog circuitry to ensure high reliability in mission-critical applications:
- High-Level Isolation: The 1500V AC isolation barrier prevents common-mode voltages from affecting measurement accuracy and ensures the safety of the monitoring equipment.
- RFI/EMI Immunity: The transmitter is built with significant shielding to resist radio frequency and electromagnetic interference, which is essential when installed near variable frequency drives (VFDs) or radio equipment.
- Automatic Cold Junction Compensation (CJC): For thermocouple inputs, the device automatically compensates for ambient temperature variations at the terminal connection, ensuring the output reflects the true temperature at the sensor tip.
- Upscale Burnout Protection: In the event of a sensor failure (broken thermocouple), the transmitter output is driven to its maximum limit (approx. 24mA), providing an immediate diagnostic signal to the control system.
Product Usage Instructions
1. Configuration and Setup
Before installation, the input range and thermocouple type must be set.
- Open the side access panel of the Lexan housing.
- Use the internal DIP switches to select the desired thermocouple type (e.g., Type K).
- Use a millivolt source or a calibrator to adjust the Zero and Span potentiometers for the specific temperature range required (e.g., 0°C to 500°C).
2. Mounting and Wiring
- Snap the unit onto a standard 35mm DIN rail.
- Input Connections: Connect the thermocouple leads to the input terminals. Ensure correct polarity (usually Red is negative in ANSI standards).
- Output Connections: Connect the 4-20mA loop wires. Since it is a two-wire transmitter, the power and signal are carried on the same two wires.
- Shielding: For best results, use shielded twisted-pair wiring and ground the shield at only one point (usually at the power supply end).
3. Maintenance
- Periodically verify the calibration using a thermocouple simulator.
- Ensure the terminal screws remain tight, as loose connections on thermocouple circuits can introduce significant temperature errors due to parasitic junctions.
Recommended Related Acromag Models
- Acromag 652T: The companion transmitter designed for RTD (Resistance Temperature Detector) inputs.
- Acromag 611T: A DC voltage/current input transmitter for general signal isolation.
- Acromag 631T: A specialized frequency-to-current transmitter for flow and speed monitoring.
- Acromag 1500 Series: Higher-density signal conditioners with 4-channel configurations.
- Acromag 250T: Legacy series flat-pack transmitters often replaced by the 651T.
