TTRU1 handheld transformer turns ratiometer

Handheld, battery-operated transformer turns ratiometer

A handheld transformer turns ratiometer with optional Go/No Go and short-circuit impedance measurement capabilities

Highly accurate in a wide temperature range, ensuring adaptability to diverse working conditions

Configurable vector lists for testing efficiency

Go/No Go open-circuit, short-circuit, and inductance tests for a prompt diagnosis

Short-circuit impedance measurements conveniently bundled with a ratiometer

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About the product

The TTRU1 is the latest handheld transformer turns ratiometer from Megger. In addition to routine polarity validation and turns ratio tests, the TTRU1 can measure short-circuit impedance (leakage reactance) with the same one-time connection.

Guided by colour-coded leads, clamps, and customisable on-screen vectors that match the transformer nameplate under test, the easy-to-follow setup ensures the right result the first time.

Perform up to 1000 turns ratio tests on a single NiMH AA battery charge. When it’s time to recharge the batteries, connect to any standard USB wall charger, or connect to your PC. When connected to the PC, TTRU1-EXP results can be downloaded, and the user guide and data sheet can also be accessed.

FAQ / Frequently Asked Questions

Can the TTRU1 be used to test transformers with similar configurations? 

The ADV, PRO, and EXP model TTRU1 can save up to 10 user-defined transformer vectors with winding voltages identified by a custom ID. After saving a custom vector, common transformer types in a system can easily be recalled, ensuring proper evaluation of results.

Which types and sizes of transformers can the TTRU1 test? 

The TTRU1 excels at testing single phase distribution transformers but can also be used for testing power transformers. With up to 250 V AC induced, the TTRU1 overcomes inaccurate results due to voltage dependence by using the patented step-up ratio testing method to test any size transformer.

How are results managed on the TTRU1?

All models of the TTRU1 automatically save results when a test is complete. Results can be exported to excel and PDF using a USB drive. For customers who need a physical copy of results, an optional USB printer is available. The ADV, PRO, and EXP models provide an additional export file for importing into PowerDB (coming soon). The PRO and EXP models offer on-screen results navigation so you can review results on site.

Can the TTRU1 test three-phase transformers? 

The TTRU1 is primarily designed for testing single-phase transformers but can also be used on three-phase transformers. The ADV, PRO, and EXP models will guide you through three-phase transformer testing with on-screen connection diagrams, providing confidence in test setup and results evaluation.

Troubleshooting

The TTRU1 will not turn on

Ensure batteries are installed.
Ensure batteries have sufficient charge.
- If using Alkaline batteries, replace batteries.
- If using NiMH batteries, charge the TTRU1 using the included USB-C to USB-A or USB-C to USB-C cable.
  - If charging does not work, replace the NiMH batteries.

The TTRU1 will not run tests or provides inaccurate ratio measurements

Turn the selection knob to “INFO”.
- Run a self-check and follow the direction on screen.
Turn the selection knob to “TTR”.
- Connect leads H1 to X1, H2 to X2, and run a 1:1 test using the 1ph0 diagram.
- Connect to a TRS1 to perform calibration verification.

The TTRU1 will not export results

Check that the USB file structure is FAT32 or exFAT.
Insert USB drive into the TTRU1, turn the selection knob to “INFO” and select “EXPORT DATA”.

Interpreting test results

Transformer Turns Ratio (TTR)

The ratio is the measured transformer turns ratio (TTR), calculated using both the voltage applied to one side of the transformer and the induced voltage measured on the other. Calculated TTR is determined from the transformer's nameplate voltages and the k factor, if necessary, as given in the table below. With the measured TTR in hand, a percentage deviation from the calculated TTR can be computed, either manually or automatically by the TTRU3. As per IEEE, the percentage deviation between measured and calculated TTR should be within a ±0.5 % tolerance.

Nameplate ratio to voltage ratio recalculation
Transformer configurations / vector groups	TVR recalculation factor (k), TVR=k*TNR
Dd	1
Dy	√3
Dyn	√3
Dz	1.5
Dzn	1.5
Yd	√3/2
YNd	1/√3
Yy	1
YNy	1
Yyn	1
YNyn	1
Yz	√3/2
YNz	√3/2
Yzn	√3
YNzn	√3
Zd	1
ZNd	2/3
Zy	√3/2
ZNy	1/√3
Zyn	1
ZNyn	1

IEEE documents cases of transformers that have a load tap changer in their low voltage side with an overall low number of turns that will cause some of the tap steps not having the same number of turns as others. Thus, the variation per tap is not uniform and might be outside the 0.5 % tolerance of deviation from nameplate values. In these cases, there are two criteria used to evaluate the results. First, the measured TTR at both extreme ends of the tap changer (highest and lowest) should be within the 0.5 % tolerance from the calculated TTR. Second, for any given tap, all three phases of the transformer should have the same voltage ratios.

Go/No Go

Go/No Go testing provides open circuit, short circuit, and inductance verification of the transformer under test. When an open or short circuit is detected, the TTRU1 will indicate which winding has an issue.

Short-circuit impedance

Short-circuit impedance values should be within 3 % of nameplate values. The TTRU1 allows the operator to input nameplate KVA and Z % and will display the measured percent error on screen.

Software and firmware updates

TTRU

latest version

TTRU1 PC Software

latest version

1.1.0.9

x-msdos-program 52.63 MB

TTRU1 Embedded Software

1.1.0.9

** Once downloaded, the zip file must be extracted before copying the .mender file to the root of a thumb drive **

zip 135.68 MB

FAQ / Frequently Asked Questions

Does the TTRU1 default to ‘step-up’ or ‘step-down’ mode to perform TTR tests on a transformer?

The TTRU1 will use ‘step-up’ mode when test voltages are above 50 V, applying voltage to the secondary/tertiary winding and inducing and measuring voltage on the primary winding. In any test mode, the instrument first performs a safety and connection test using a low voltage (less than 1 V). ‘Auto test’ mode uses the results of this test to verify that testing can progress in ‘step-up’ mode.

How often should the TTRU1 be calibrated?

You should perform a complete performance and calibration check of your TTRU1 at least once every year. This will ensure that the TTRU1 is functioning correctly over the entire measurement range. Anyone can use the optional Megger TRS1 (Transformer Ratio Standard) to calibrate a TTRU1. This high accuracy reference ratio standard can provide ratios in both ‘step-down’ test mode (for traditional ratio test instruments and the TTRU1) and ‘step-up' test mode (for the Biddle Hand Crank TTR and the TTRU1). Megger performs a TTRU1 calibration on each new or repaired unit before sending it to a customer.

What maintenance should be performed on the TTRU1?

Maintenance should be performed only by qualified personnel familiar with the hazards involved with high voltage test equipment. Read and understand Sections 1, 2, 3, 4, and 5 of the User Guide before performing any service. The TTRU1 requires only periodic inspection. Inspect all hardware items to ensure all are in good condition. The TTRU1 may be cleaned periodically. In doing so, do not allow water to penetrate panel holes. An all-purpose household spray cleaner can be used to clean the panel. Polish with a soft, dry cloth. Clean the cables and mating panel receptacles with isopropyl or denatured alcohol applied with a clean cloth.

What should I do if the TTRU1 needs repairing?

Any service or repair of this equipment should be performed only by qualified persons who are aware of electrical hazards and the necessary precautions required to prevent injury. Megger offers a complete repair and calibration service and recommends that its customers take advantage of this service for routine maintenance or in the event of any equipment malfunction. In the event a service is required, contact your Megger representative for a product Return Authorisation (RA) number and shipping instructions. Ship the product prepaid and insured and marked for the attention of the Megger Repair Department. Please indicate all pertinent information, including catalogue number, serial number, and problem symptoms.