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  RD-33 Dytronic Three-Phase Reference Standard


CT Admittance Testing

The Tx Auditor can perform admittance testing by injecting a known frequency into the secondary of an in-service transformer and detecting the circuit admittance. Admittance testing can be performed with or without load on the primary. Circuit admittance of any particular current transformer installation is nearly constant throughout the operating range, unless a fault is present. Therefore, if the admittance measurement shows a deviation from normal, it is likely that the transformer or installation is defective. When performing an admittance test, failure is easy to detect, testing time is reduced and increased user safety is accomplished.

Portable Safe Operation

Tx Auditor is packaged in a durable, light weight, high-impact polypropylene case. Locking connectors prevent disconnect during testing eliminating any chance of an open CT which can cause injury to the operator. The Auditor performs a self-analysis procedure at start-up to ensure proper operation and user safety. The unit monitors voltage and current and prevents any scenario that may cause an open CT. From the Transformer Auditor's design concept, engineering and production, our staff works to ensure that your safety is a priority.

Choice of Accuracy Class

The accuracy of the Tx Auditor is provided by the choice of an embedded Radian RD-20 (0.04%) or RD-21 (0.02%) Reference Standard. Select the standard that meets your budget and provides the accuracy necessary to confidently test your transformer installations.

Convenient Clamp to Clamp Ratio Testing

The Tx Auditor has the ability to use a calibrated current clamp for scenarios that do not provide convenient access to directly measure the CT's secondary signal. Multiple clamp inputs for various primary current sensors allow for the user to choose the best sensor for each unique testing application. Testing can be performed without a test switch installed increasing safety and reducing time on-site. In many cases, the need for re-wiring for test or replacing the CT is eliminated further enhancing operator efficiency.


The Tx Auditor™ is designed with Radian's years of leadership and experience in electricity measurement. The result is a technologically advanced and industry-leading solution for testing current and potential transformers while they remain in service.

The Tx Auditor incorporates technologies from our state of the art burden testing module, ultra performance watthour standards and the long-established model 505 transformer analyzer. The Auditor provides functionality and testing capability on-site that, until now, required several pieces of equipment.

Designed with metering professionals in mind the Tx Auditor is light weight, extremely durable and provides unprecedented performance.

Technical Data

Operation Range Specification
Secondary Voltage
V1 - 60 to 600 volts
TX-21 ± 0.02%
TX-20 ± 0.04%
Primary Voltage
(0.02 to 2 V RMS)
(using mV probes)
± 0.04% + High Voltage Sensor Error
Sensor Link - Volt LiteWire
LW-8014, LW-8013, LW-8012
Secondary Current
IS1 - 0.02 to 20 Amps TX-21 ± 0.02%
TX-20 ± 0.04%
(2 to 800 mA)
(using Radian Probes)
± 0.04% + Clamp Error
Primary Current
(0.02 to 3 V RMS)
(using mV probes)
± 0.04% ± 0.1 mA + Clamp Error
3000-48, 3000-36, 3000-24
MR411,MR521, LW2000
(10 to 800 mA)
(using Radian Probes)
± 0.04% ± 0.1 mV + Clamp Error
CT Ratio Range Up to 3000:5 See Clamps Specification
Admittance 1.0mS to 125 mS
± 5% F.S. ± 0.02 MS
0.14 Ohms Insertion Burden
Burden Resistance 0.1 - 8.0 Ohms ±1%
Burden Resistance
Ratio Accuracy For burdens within CT mfg burden specs 2%

Environmental Physical Attributes Battery Input Power
Operating Range: -20° to 50° C, -4 to 122° F Size (LxWxH): 15.14in x 12.13in x 6.81in,
384mm x 308mm x 172mm
Continuous Run Time: 5hrs Battery Charger Input: 100 - 240 VAC
Storage Range: -20 to + 70° C, -4 to 158° F Weight: 24 lbs / 10.8 Kg Standby Time: 43 hrs Aux Power Charger Input: 24 V DC
Humidity: 10 to 95% non-condensing   Charge Time: 3 hrs  

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