Why You Should Care about Ratio, Burden and Admittance Testing on Transformer-Rated Installations

Why You Should Care about Ratio, Burden and Admittance Testing on Transformer-Rated Installations

Why You Should Care about Ratio, Burden and Admittance Testing on Transformer-Rated Installations 150 150 Probewell
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Keeping transformer-rated installations within the operating range recommended by ANSI plays a critical role in the financial health of both utilities and their customers.

Mariana Napoli | Sales and Marketing Director | Probewell Lab Inc.
Mariana Napoli
Sales & Marketing Director

Current and potential transformers rarely have problems, but they can arise, whether due to magnetization of the CT over time, faulty wiring, a closed CT shunt, corrosion on the switches or a bad meter insertion at the socket. When these problems occur, costs quickly add up, and not just to fix the hardware issue.

[vc_empty_space][vc_message icon_fontawesome=”fa fa-exclamation-circle”]It’s imperative that these types of issues be promptly caught and resolved or the utility could lose several thousands in revenue every month that the problem remains undetected.[/vc_message][vc_empty_space]

Not to mention the hassle when it comes time to announce additional billing for backlogs to the customer, or an upward rate adjustment (sometime up to 300%) in order to rectify the situation.


On the other hand, when assessing an installation in response to a high bill complaint, utility companies could discover that they have been over charging their customers. When this happens, damage control is needed. But even after the utility fixes the problem and negotiates the amount to be reimbursed to the customer, the situation will have eroded trust in the company’s services and tarnished its reputation.


These types of problems can easily be detected when servicing a transformer-rated installation by performing  CT/PT ratio, burden and admittance tests.


Better safe than sorry!


With good planning, you can manage the risks that stem from these challenges. For instance, performing a full assessment, including ratio, burden and admittance tests on transformer-rated installations upon deployment as part of a routine quality assurance check. Then be sure to include it in your yearly maintenance plan, which is already mandatory in some states. To do so, an easy-to-use testing solution that fits seamlessly into your usual maintenance routine is vital…


Probewell | Site Tester | ST-2/XT3

Why the XT Series is up to the task?


  • Ergonomic design
  • Advanced, yet easy to use
  • Uncompromised accuracy

In response to the ever-growing need for efficiency and portability, we proudly introduce the ST-3/XT3, the first socket-type transformer-rated site tester with integrated WiFi technology. it’s well-suited to the task and here’s why:


The portability and accuracy of the ST-3/XT3, paired with the advanced, yet intuitive Probewell Connect application is the best solution when it comes to testing transformer-rated installations.


Run all the required tests from a single measurement device weighting only 4.5 lb.

Probewell | Probewell Connect app | Test | Power Quality (PQ) Power Quality (PQ) 
Probewell | Probewell Connect app | Test | Real-Time Waveform Real-Time Waveform
Probewell | Probewell Connect app | Test | Total Harmonic Distortion Total Harmonic Distortion
Probewell | Probewell Connect app | Test | Phasors Phasors
Probewell | Probewell Connect app | Test | CT Burden CT Burden
Probewell | Probewell Connect app | Test | CT & PT Ratios Test CT & PT Ratios
Probewell | Probewell Connect app | Test | Admittance Admittance


Probewell | ST-3 XT3 Installation Diagram


Control it wirelessly from a laptop or mobile device using the Probewell Connect app.


Probewell | Probewell Connect 2.0 | Power Quality Test | Real-Time Waveform

  • Quick and easy setup
  • Customizable configuration
  • Task automation
  • Validation of test results at a glance
  • Undeniable traceability
  • Data-driven insights
  • Export report as CSV or PDF
Full RMS and line cycle measurement of both secondary and primary currents and voltages 
  • Rooted at its core is high-performance multiphase energy-metering circuitry.

Compatible input voltage 

The ST-3/XT3 series is powered directly from the meter base for quick and easy setup between phase and neutral.
  • From 100 to 480 VAC

Plug & “Play” and read all three phases simultaneously

Connect the CT and PT measurement accessories to the front of the device and test all three phases simultaneously, thereby negating the risk of inaccurate measurements due to current fluctuations.

Uncompromised accuracy

The tester has three built-in current sensors of up to 20 amperes to analyze the secondary current directly at the meter socket.
  • 3 current sensors up to 20 A
  • Typical accuracy of 0.05%
  • Maximum accuracy of 0.1%
[vc_empty_space][vc_message message_box_color=”grey”]Regularly testing their transformer-rated installations as part of their quality assurance program is a good practice for utility companies. Probewell XT Series wireless site testers are perfect for the task: they are portable, easy to use, compatible with multiple forms and offer a wide range of tests that are key to maintaining a healthy electrical installation and keeping customers satisfied.[/vc_message][vc_empty_space]


Main features of the ST-3/XT3 wireless site tester

Single-phase 3S and 4S
Polyphase 5S*, 6S, 8S, 9S, 35S* and 45S*
*Adapter required (included)
Voltage 100 – 600 VAC
Working voltage 100 – 480 VAC +/- 10%
Line frequency 58-62 Hz
Bypass circuit 20 A (max for CT Rated)
Circuit breakers 2 x 1 A (press-to-reset mechanism)
RMS current ±0.1% maximum
RMS voltage ±0.1% maximum
Frequency ±0.1% maximum


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Other advantages of using ultralight XT Series wireless site testers

Probewell | ST-3/XT3 | Managing the Risk | Minimize human error


Manage risk

  • Quickly setup the testing device and speedup the assessment process without ever compromising safety.

Minimize human error

  • Minimize the time spent doing clerical work and other redundant back-office tasks by automating the reporting process.

Best practices

  • Stay “ahead of the game,” saving time and money in the long run. Adopt the ST-3/XT3 as a standard tool for quality assurance.

Probewell Connect

  • The advanced, yet simple solution literally at your fingertips. Create reliable reports in CSV or PDF format and share your findings via email.


Want to know more about our wireless meter tester? Get in touch!

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