Digital Transformer Ratiometer (Megabras Brand Only)

Digital Transformer Ratiometer (Megabras Brand Only)


Digital Transformer Ratiometer (Megabras Brand Only)



SKU: AME-112216-43


Digital Transformer Ratiometer (Megabras Brand Only)


The Transformer Ratiometer TR8703 is a lightweight, rugged, portable instrument designed for onsite testing of power, potential and current transformers. No user calibration, range selection, hand cranking or tedious balancing is required. During each test cycle, the TR8703 automatically checks for H/X lead reversal, continuity of tested circuits/windings (if configured) and short circuit conditions (high current).

Upon completion of a test cycle, the TR8703 displays the turns ratio, excitation current, polarity and deviation which are useful parameters in diagnosing and predicting a variety of faults that occur in power, potential and current transformers.

The TR8703 utilizes an advanced, low-voltage, step-down measurement technique in which the high voltage “H” windings are subjected to test excitation. This results in greater operator safety and the ability to test a much wider array of transformer types and sizes.

In addition, the TR8703 allows the user to store the data in automatic or manual mode after each test eliminating the need to write down the test results. Each measurement record is date and time stamped providing complete test information. The user can also save Nameplate voltages and compare the results as the data is being gathered. The data can later be downloaded to a PC and analyzed using a software which is included with the product.

Digital transformer ratiometer

Technical specifications

Ratio Range (VT/PT)

Auto range: 0.8000 to 8000:1.

Accuracy (VT/PT)

Ratio Range
0.8000 to 9.9999
10.000 to 999.99
1000.0 to 4999.9
5000.0 to 8000.0
Accuracy (% of reading)
± 0.2%
± 0.1%
± 0.2%
± 0.25%

Ratio Range (CT)

Auto range: 0.8000 to 1000.0.

Accuracy (CT)

Ratio Range
0.8000 to 1000.0
Accuracy (% of reading)
± 0.5%

Excitation signal

VT/PT Mode: 32 Vrms max.
CT Mode: Auto Level 0 to 1 A, 0.1 to 4.5 Vrms.

Excitation current display

Range: 0 to 1000 mA; Accuracy: ± (2 % of reading + 2 mA).

Excitation frequency

70 Hz.


Dual line alpha-numeric LCD, 16×2 characters with contrast adjustment and backlight control. Day/night visible.


English, Spanish, French, Italian, German, Portuguese.

Measurement Method

In accordance with IEEE Std C57.12.90™-2006.

Power supply

Two 12 V, 5×2, 1650 mAh NiMH rechargeable battery packs.

Battery life

Up to 10 hrs of continuous operation. Low battery indication.

Battery charger

Universal input (90 to 264 Vrms input) smart recharger.

Charging time

< 4 hours for full charge.

Data storage

99 objects with 99 tests each.

Data / Time

Battery-backed, Real-time clock.


USB. 2.0 compliant, optically isolated, 115.2 kB.


Analysis software included.


XLR connectors.


15 ft (4.6 m) H & X shielded with large color-coded industrial alligator clips in carrying bag.


Heavy duty polypropylene case, UL 94 V0.


IEC 68-2-6 (1,5 mm to 55 Hz).


IEC 68-2-27 (30 G).


IEC 68-2-32 (1 m).

Index of protection

IP40 (instrument lid open) per EN 60529: IP53 (Instrument lid closed) per EN 60529.

Operating temperature

-10ºC to 50ºC.

Storage temperature

-20ºC to 60ºC.

Relative humidity

10 to 85% RH @ 35ºC.

CE Mark


Duble insulating


Safety rating

EN 61010-1; 50 V CAT IV; Pollution Degree 2.


272 x 248 x 130 mm.


3.7 kg.

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