AC Ratio Transformers

An AC ratio transformer is a high-precision inductive device, often used as an inductive voltage divider, that produces an output AC signal in a defined ratio to the input. It uses precision transformer windings and selected taps or decade switches to divide AC voltage with excellent stability and accuracy. Rather than generating or amplifying a signal, it precisely scales an existing AC input so engineers can compare, verify, and calibrate instruments against a known ratio standard.

These devices achieve high accuracy through precision inductive design, stable winding geometry, and excellent linearity over their operating range. Compared with resistive methods, they can offer very low phase error and strong ratio stability across frequency. In multi-decade models, carefully engineered switching arrangements help preserve accuracy while changing settings. The result is a metrology-grade ratio standard suitable for traceable calibration work.

Typical applications include calibration laboratories, national metrology institutes, transformer test setups, AC bridge circuits, resolver and transducer testing, and other environments where a precise AC voltage or current ratio must be established or verified. They are used to calibrate electrical measurement instruments, validate ratio accuracy in transformers and sensors, and support specialised research and industrial measurement tasks.

A decade ratio transformer is an adjustable ratio standard with multiple selectable taps or decade switches, allowing very fine ratio setting across a broad range. It is ideal for simulation and precision calibration. An AC ratio isolation transformer is normally a fixed-ratio device, typically 1:1, sometimes with a centre tap for 0.5 ratio output. Its role is to provide accurate isolation, phase inversion, or balanced output in AC measurement circuits while minimising loading effects.

The 1372 series provides a more automated calibration workflow by combining a precision ratio transformer reference with computer-based control and data handling. This allows users to step through ratio points, run repeatable procedures, and capture calibration results with less manual intervention. It improves efficiency, reduces the chance of operator error, and supports more consistent documentation in laboratory environments.

Yes. These high-precision AC ratio transformers are typically supplied with calibration data and certificates traceable to recognised national standards. This supports confidence in the stated performance and helps users meet internal quality and accreditation requirements.

Yes. Although they are designed for long-term stability, periodic recalibration is recommended to confirm that performance remains within specification over time. Maintenance needs are generally low because these are largely passive devices, but good handling practices, protection from humidity and shock, and proper care of mechanical switches are important for preserving accuracy.

The 1372A is a complete calibrator package that includes the precision AC ratio reference transformer. The 1372B provides the same calibration and automation functionality but is supplied without the reference transformer. This gives users the option to use an existing standard if they already have one.

Choose a decade ratio transformer if you need adjustable high-resolution ratio settings for simulation and calibration. Choose an AC ratio isolation transformer if your priority is accurate 1:1 isolation, signal inversion, or balanced output in a measurement circuit. Choose the 1372 series calibrator if you need an integrated, automated solution for frequent calibration work and improved workflow efficiency.