DYTRONIC PRIMARY TRANSFER STANDARD

RADIAN RD-22

The RD-22 by Radian Research is a high-accuracy energy reference standard engineered for laboratory and metrology-grade energy measurement.

Built for professionals who demand uncompromising precision, ±0.005% accuracy, and exceptional long-term stability, the RD-22 delivers NIST-traceable performance ideal for national metrology institutes, calibration laboratories, and high-end meter testing applications.

Designed for both standalone use and integrated test environments, the RD-22 sets the gold standard in precision measurement.

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Product Highlights

The RD-22 provides ±0.005% (50 ppm) energy accuracy, delivering a refined accuracy class suited for advanced calibration, metrology, and precision measurement applications. As a single-phase reference standard, it supports high-confidence verification and calibration tasks where minimized uncertainty and consistent performance are essential.

Voltage accuracy is 0.0025% (25 ppm) and direct AC current accuracy is 0.0035% (35 ppm) at TCAL, offering tightly controlled measurement capability across the supported operating ranges. Long-term drift is managed through a stability specification of 3 ppm × √month, maintaining reliable performance over extended periods. For energy measurements, the temperature coefficient is 5 ppm/°C, ensuring predictable behavior with environmental variation.

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FEATURES

Laboratory-Grade Accuracy with the RD-22

Power and Energy accuracy: ±0.005% (50 ppm)
Voltage accuracy: 0.0025% (25 ppm)
Current accuracy: 0.0035% (35 ppm)
DC to AC transfer accuracy: 0.005%
Stability: 3 ppm × √month
Single-phase reference standard

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Trusted by Leading Laboratories and Institutions Worldwide

What Makes the RD-22 a Primary Transfer Standard

True DC to AC transfer. Calibration mode inputs accept external DC voltage and DC current primary references, so the RD-22’s internal reference can be calibrated directly, with ±0.005% DC to AC transfer accuracy.
Dytronic measurement technology. A RADIAN-designed integrating analog to digital converter and a hermetically sealed reference set.
Concentric core current comparator. An electronically compensated, autoranging external current comparator whose shielded inner core is highly insensitive to conductor position.
Repeatability of ±0.00001% (100 parts per billion) for a 15-minute test.

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Which Laboratory Standard Is Right for You?

The RD-22 and the RD-22 Ultra Stable are single-phase primary transfer standards that carry traceability into your lab. The RADIAN RS-933 is a sourcing standard for calibrating in-house. It can’t be shipped to NIST for calibration testing, so an RD-22 is recommended as the transfer standard that carries traceability to it.

Model	Energy accuracy	Best for
RADIAN RD-22	±0.005%	Calibration labs and metrology programs that need a primary transfer standard
RD-22 Ultra Stable	±0.002%	The most demanding metrology and research labs, at 120 V or 240 V and 5 A
RADIAN RS-933	Down to 50 ppm (0.005%)	In-house calibration as a sourcing standard, with an RD-22 carrying traceability

RADIAN RD-22 FAQ

What is the RD-22 operating range?

40 to 600 VAC (autoranging) and 0.2 to 125 A or 0.2 to 200 A (autoranging, by option), at 45 to 65 Hz and any power factor. It is specified at 23 °C ±2 °C, with an extended operating range of 18 °C to 30 °C.

The RADIAN RD-22 on a transparent background.

How accurate is the RD-22 across its range?

±0.005% at key calibration points and for DC to AC transfer, and ±0.01% worst case anywhere across its operating range (any voltage, current or power factor). All accuracies are in percent of reading, not percent of scale.

How often should the RD-22 be recalibrated?

Its recalibration interval is 365 days. RADIAN Calibration Services recalibrates it in our ISO/IEC 17025-accredited lab, with results traceable to the SI through NIST.

A young woman using a RADIAN DC reference standard on a WECO 4330X as a part of RADIAN Calibration Services.

Why would a lab use more than one RD-22?

Averaging several standards reduces measurement uncertainty. Our white paper, Strength in Numbers, explains the approach, and the RADIAN RM-111 can average up to three reference standards in a single test.

How is the RD-22 different from the RD-22 Ultra Stable?

Both are single-phase primary transfer standards built on the same platform. The RD-22 Ultra Stable is rated at ±0.002% energy accuracy, compared with ±0.005% for the RD-22, with an enhanced stability profile for the most demanding labs. The Ultra Stable operates at 120 V or 240 V and 5 A, while the RD-22 autoranges from 40 to 600 V and 0.2 to 125 A or 200 A.