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Description
Weight: 4.5 lbs | Size: 6.9″ X 7.4″
Probewell’s socket-type wireless field testers are the baseline for utilities looking to minimize risk while enhancing their productivity and profitability on the go.
Test the Power Quality test, the CT & PT Ratios, the CT Burden or Admittance and thoroughly assess electrical installations, securely records, and easily share critical actionable insights needed to make nothing less than evidence-based decisions.
All the while minimizing risks, enhancing team productivity and time management.
- Revolutionary Design
- Advanced, yet simple to use
- WiFi Technology
- Offers all the required tests
- Uncompromised Accuracy
Control it from a laptop or cell phone
- Customized configuration
- Task Automation
- Validation of test results at a glance
- Export report as CSV or PDF
Verification Process
Speed up the process without ever compromising safety
The ST-3/XT3 is a sophisticated yet rugged tool, simple to use and controlled remotely thanks to the integrated Wifi and the Probewell Connect application. The application is offered free of charge and can be installed on your laptop, tablet or cell phone.
Above all, the Probewell Connect user interface gives you access to a complete range of tests to securely test the quality of your CT rated installations.

ST-3/XT3 accessories
Documentation:
- Quick-Start Guide and User Guide
- Factory calibration report
Hardware included:
- 5 spares removable twist tabs
- Adapter for 5S, 35S and 45S
- Update Cable
(not included)

Uncompromised precision
Three current sensors analyse with a typical accuracy of 0.05%.
How Does It Work?
Embedded within the ST-3/XT3, is a high performance multiphase energy metering circuitry.
Thereby allowing a full RMS and line cycle measurement of both secondary (at the meter base) and primary (with accessories) currents and voltages.
In short, the ST3/XT3 offers elaborate test modes that can leverage such measurements to assess the Power Quality on the secondary side or perform complete transformer ratio analysis
Lightning Quick Setup!
The Form selector switch and removable twist tabs enable a toolless configuration to match any transformer rated meter base form.
Consequently, you will be able to test sites with any of these CT rated meter forms:
Single-Phase: 3S and 4S
Polyphase: 5S, 6S, 8S, 9S, 35S and 45S
Fitzall™: Classe TC
Setting-up your test has never been easier; you’ll be testing in no time.
Integrated WiFi Technology
Wirelessly efficient
Moreover, by maximizing both your device’s camera and GPS, many manual operations are shortcut to save you valuable time.


No network, not a problem!
In other word, its robustness, compact size and ease of operation make it an indispensable tool for testing sites in remote areas.
Leverage crucial digital insights!
Export and share test results as a PDF or CSV file.

Further more, you can quickly export all your testing data in PDF or CSV format to facilitate integration with your local systems for future analysis.
Click the links below to download a sample file:
Several other tests are also available, get a sample upon request.
How to retrieve the test reports:
Compatible Forms Supported by the ST-3/XT3 Site tester
Transformer |
1S |
2S |
3S |
4S |
5S |
6S |
8S |
9S |
12S |
14S |
15S |
16S |
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35S |
36S |
25S |
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45S |
46S |
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Site tester |
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Self-Contained |
CT-Rated |
Self-Contained |
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Compatible Meters | |
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Single-Phase | 3S and 4S |
Polyphase | 5S*, 6S, 8S, 9S, 35S* and 45S* *Adapter required (included) |
Compatible devices | |
Operating systems | IOS®, Android®, Windows® |
INPUT | |
Voltage | 100 – 600VAC |
Working Voltage | 100 – 480VAC +/- 10% |
Line Frequency | 58-62Hz |
Bypass Circuit | 20A (max for CT Rated) |
Circuit Breakers | 2 x 1A (press-to-reset mechanism) |
COMMUNICATION | |
Wireless | 802.11b/g Access Point Only |
I/O Port | Full duplex for wired updates only |
Update | USB Cable |
MULTIFUNCTION MEASUREMENTS ACCURACY | |
RMS Current | ±0.05% maximum |
RMS Voltage | ±0.05% maximum |
Frequency | ±0.05% maximum |
environment | |
Operation Temperature | -4° to 140°F (-20° to 60°C) |
Storage Temperature | -4° to 140°F (-20° to 60°C) |
Humidity | 0% to 95% (non condensing) |
Physical Dimensions | |
Test Socket (Diam. x L) | 6.5” x 7.4” |
Weight | |
Test Socket | 4.5 lb |
Warranty | |
Parts and Labor | 2-years limited*** |
SUPPORTED TESTS | |
Power Quality Analysis | Vrms, Irms, Frequency |
Active Power (W) | |
Reactive Power (VAR) | |
Apparent Power (VA) | |
Power Factor | |
Vrms Factor | |
Vrms THD, Irms THD | |
Current Phase Angle | |
Voltage Phase Angle | |
Phase Sequence Detection | |
Waveform Viewer | 80ms of data per channel |
CT Burden | 0.1, 0.2, 0.5, 1.0, 2.0, 4.0, 8.0 |
Admittance | |
SUPPORTED TEST (WITH ACCESSORIES) | |
CT primary to secondary ratio | |
CT primary –˃ secondary phase | |
PT primary to secondary ratio | |
PT primary –˃ secondary phase | |
INCLUDED | |
Deluxe Double Carrying bag | Update cable |
User’s manual | 5 Removable Twist Tabs Plus 5 spares |
Quick Start Guide | Calibration report |
5S, 35S, 45S adapter |
(Click to expand!)