High-Precision Loop Calibrator – UNI-T UT705

Precision Loop Calibration for Industrial Systems

The UNI-T UT705 represents a vital asset for maintaining the accuracy of industrial control loops. In modern manufacturing and processing plants, the 4-20mA current loop remains the industry standard for signal transmission; even a minor deviation can lead to improper valve positioning or incorrect sensor data. The UT705 provides a high-accuracy, portable solution for “loop-tuning,” allowing technicians to simulate field signals and verify the entire control chain from the primary element to the control room.

Advanced Sourcing and Measurement Logic

The UT705 is more than a standard multimeter; it is a dedicated signal generator designed for the rigors of industrial maintenance.

• Simultaneous Source & Measure: The device allows for the measurement of DC current while sourcing a known signal, facilitating the rapid identification of loop errors or high-resistance connections.

• DC Current Sourcing (0-24mA): Provides the ability to simulate a transmitter’s output to verify the response of a controller or PLC input card.

• DC Voltage Sourcing (0-10V): Essential for checking motor speed drives and other voltage-controlled industrial hardware.

• 24V Loop Power Supply: Internal 24V DC supply allows for the powering and testing of 2-wire transmitters in isolation from the main power grid.

Optimized Workflow with Automated Functions

To streamline repetitive calibration tasks, the UT705 includes intelligent automation features:

• Auto Step & Ramp: Automatically increments the output signal in fixed steps (e.g., 25% increments) or as a smooth ramp. This is indispensable for checking the linearity and hysteresis of pneumatic and electronic control valves.

• Percentage Display: View current readings directly as a percentage of the 4-20mA scale (0%, 25%, 50%, 75%, 100%), eliminating the need for manual calculations in the field.

• High-Resolution Interface: A high-contrast, backlit LCD ensures that critical data is readable in the dim light of electrical switchgear rooms or under direct sunlight.

Rugged Industrial Reliability

Housed in a shock-resistant, ergonomic casing, the UT705 is built for the demanding conditions of South African industrial sites. Its robust terminal design protects against accidental overvoltage, while the impact-resistant frame ensures longevity in professional toolkits. Powered by a standard 9V battery with an intelligent power-saving mode, it provides consistent, reliable performance throughout long maintenance shifts.

Key Features & Technical Advantages:

• High-Accuracy Performance (0.02%): Delivers professional-tier precision for critical industrial control parameters.

• 24V Loop Power: Powers 2-wire transmitters directly, simplifying off-line diagnostics and bench testing.

• Simultaneous Source and Measure: Enables comprehensive auditing of loop integrity in a single pass.

• Programmable Signal Output: Includes Auto-Step, Auto-Ramp, and Manual-Step modes for versatile testing.

• HART Resistor Support: Built-in compatibility for working with HART-enabled devices without signal interference.

• Overload Protection: Engineered for safety in high-stakes electrical environments with a rugged terminal layout.

Professional Application Scenarios

• PLC/DCS Loop Auditing: Verifying that analog input channels are correctly scaled and responding to field signals.

• Control Valve Calibration: Using the ramp function to ensure smooth actuator travel and correct “open/close” seat positioning.

• Transmitter Bench-Testing: Providing power and a reference signal to pressure and temperature transmitters during routine service.

• Instrument Scaling: Correcting zero and span errors in industrial instrumentation to meet ISO-9001 quality standards.

• Fault Isolation: Simulating known signals to determine if a fault lies within the field wiring, the instrument, or the control system.

Maintenance and Best Practices

To maintain the professional accuracy of your UNI-T UT705, follow these protocols:

• Terminal Cleaning: Periodically check the input/output terminals for dust or oxidation, which can introduce contact resistance in high-precision current measurements.

• Lead Integrity: Use only high-quality, low-impedance test leads to ensure the accuracy of the 0.02% base measurements is not compromised.

• Battery Replacement: Replace the 9V battery as soon as the low-power indicator appears to maintain a stable internal reference for sourcing signals.

• Recalibration: For ISO-certified facilities, it is recommended to have the unit professionally calibrated annually to verify its high-precision rating.