The Megger TTRU1 is a handheld transformer turns ratiometer designed for safety, reliability, and ease of use in testing power, distribution, and instrument transformers. It provides essential information for making informed electromechanical maintenance decisions. The device comes in several models: TTRU1-BASIC, TTRU1-ADV, TTRU1-PRO, and TTRU1-EXP, each offering varying levels of functionality and induced voltage capabilities.

Function Description

The TTRU1 measures transformer turns ratio, impedance (Go/No Go and Short Circuit Impedance/Leakage Reactance), and phase deviation. It supports both single-phase step-up and step-down excitation methods. The device is equipped with a full-color Hi-Bright LCD screen for displaying measurement data and a rotary knob for selecting different functions. It features an intuitive button interface for navigation, data entry, and test control.

The TTRU1-BASIC model provides fundamental turns ratio testing with induced voltages up to 37.5 VAC. The TTRU1-ADV expands on this with 62.5 VAC induced voltage, Go/No Go impedance testing, customizable vector lists, and guided three-phase tests, along with PowerDB import capabilities. The TTRU1-PRO further enhances functionality with 125 VAC induced voltage, step-up ratio measurement, phase deviation, customizable transformer nameplates, and guided three-phase tests. The top-tier TTRU1-EXP model offers 250 VAC induced voltage, short circuit impedance/leakage reactance testing, phase deviation, comprehensive customizable vector lists and transformer nameplates, guided three-phase tests, PC communication, and includes a printer and hand crank USB charger.

The device allows users to set maximum test voltages, frequency (50/60 Hz), and test buzzer (On/Off). It supports various standards for tap configurations, including ANSI (H,X), IEC (1U,2U), Australian (A#, a#), and GOST (A,a). Users can define ratio error limits (0.5%, 1.0%, 1.5%, 2.0%) and phase deviation limits (0.5°, 1.0°, 5.0° for PRO and EXP models). Temperature correction for winding temperature and Z% to temperature is available on the EXP model.

Important Technical Specifications

Input Power: 6 x IEC LR6 1.5 V alkaline (AA) or 6 x IEC HR6 1.2 V NiMH rechargeable (AA) batteries.
Battery Life: Approximately 1000 TTR tests on a single charge. Storage life is 1+ years for NiMH and 5+ years for alkaline batteries.
Battery Charging: USB-C when set to NiMH batteries. Protection against alkaline charging is included. PowerEx PRO NiMH battery charging operates from 0 to 45 °C.
Output Voltage: Single phase, 1-50 V.
Output Current: 0.1 mA - 1 A.
Safety: IEC 61010-1:2010 + AMD1:2016.
EMI/EMC: IEC 61326-1:2012.
RoHS2: EN50581.
Vibe/Shock: MIL-STD-810G.
Ingress Protection: IP54.
Display: Full color 88 mm (3.5 in) 320 x 240 px Hi-bright LCD screen with 'auto dim' and 'auto off' features.
Internal/External Data Storage: Up to 10 custom vector storage, up to 10,000 sets of single-phase results internal storage. Transferable via USB 2.0 drive.
PC Communication: USB-C connection to PC (EXP ONLY) for data download with custom GUI.
Printer (optional/included with EXP): 51 mm (2in) thermal printer, prints all measurement data displayed on GUI.
Environmental Operating Temperature: -20° to 50 °C (-4° to +122 °F).
Environmental Storage Temperature: -30° to 70 °C (-22 ° to +158 °F).
Relative Humidity: 0-90%, non-condensing.
Dimensions: 22.8 x 10.5 x 7.5 cm (8.98 x 4.1 x 2.95 in).
Weight: 1 kg (2.2 lbs).

TTR (Turns Ratio Measurement)

Methods: Single phase step up, single phase step down.
Range and Accuracy (Step down excitation):
- 25-50 V: ±0.05% for 0.8–1000, ±0.10% for 1001–2000, ±0.30% for 2001–15000, ±1.0% for 15000+.
- 1-24 V: ±0.10% for 0.8–1000, ±0.20% for 1001–2000, ±0.60% for 2001–15000, ±2.0% for 15000+.
Range and Accuracy (Step up measurement):
- 25-250 V: ±0.05% for 0.8–200 (most Power Tx).
- 1-24 V: ±0.10% for 0.8–200.
Excitation Current Resolution: 0.1 mA (0.1 mA – 100 mA), 1.0 mA (101 mA - 1000 mA).
Excitation Current Accuracy: ±1% Reading, ±0.1 mA.
Frequency Accuracy: ±1% Reading, ±0.1 Hz.
Phase Range: 0-360°.
Phase Accuracy: ±0.05°.
Max Voltage Output: 45 V AC peak.

SCI (Short Circuit Impedance Measurement)

Methods: Single phase.
Frequency Range: 40-480 Hz.
Impedance Measurement Range: 0.1 Ω - 700 Ω.
Impedance Accuracy: ±1% reading, ±0.01%, ±1% reading, ±0.10 mΩ.
Reactance Measurement Range: 0.1 Ω - 700 Ω.
Reactance Accuracy: ±1% reading, ±0.01%, ±1% reading, ±0.10 mΩ.
Inductance Accuracy: ±1% reading, ±10 μH.
Power Factor Range: 0.1% - 100%.
Power Factor Accuracy: ±5% reading, ±0.1%.
AC Current Accuracy: ±0.2% reading, ±0.1 mA.

Usage Features

Intuitive Interface: The rotary knob allows for easy selection of TTR, Go/No Go Impedance, Short Circuit Impedance, Results, Settings, and Info functions.
Test Setup: Users can configure primary and secondary winding parameters, including tap, connection, L-L voltage, and current (for CTs).
Vector Management: Customizable vector lists allow saving and recalling test setups. Custom vectors can be updated, hidden, or deleted. The PRO and EXP models allow upgrading custom vectors to custom nameplates, which fix primary and secondary winding information, allowing only tap/connection selection.
Guided Three-Phase Tests: PRO and EXP models guide users through three-phase transformer testing, highlighting the next phase to be tested.
Test ID: Users can enter a TEST ID for each test, facilitating data organization. The device can automatically generate a default TEST ID if none is entered.
Results Viewing and Management: Test results, including measured ratio, test voltage, current, polarity, calculated ratio, and % error, are displayed and automatically saved. Results can be sorted by date, TEST ID, or % error. Individual results can be loaded to reload the test setup.
Data Export: Results and logs can be exported to a USB thumb drive.
PC Software: Installation of PC software enables remote data viewing and download via USB.
PowerDB Import: TTRU1 data can be imported into PowerDB using the combined 3Ø form.
Self-Check: The device includes a self-check function to verify instrument performance.
Language and Regional Settings: Adjustable language (English, German, French, Spanish), number format, date format, and time format.
Display/Battery Settings: Configurable screen dim, auto-off duration, screen brightness, and battery type (Alkaline/NiMH).

Maintenance Features

Periodic Inspection: The TTRU1 requires only periodic inspection to ensure all hardware items are in good condition.
Cleaning: The unit can be cleaned periodically with an all-purpose, household spray cleaner and a soft, dry cloth. Cables and mating panel receptacles should be cleaned with isopropyl or denatured alcohol.
Calibration: A complete performance and calibration check is recommended annually to ensure proper functioning across the entire measurement range.
Repairs: Any service or repair should be performed by qualified personnel aware of electrical hazards. Megger offers a complete Repair and Calibration Service. Customers should contact their Megger representative for a Return Authorization (RA) number and shipping instructions, providing catalog number, serial number, and problem symptoms.
Software Update: The device software can be updated from a USB thumb drive or by downloading the latest installer from the Megger website.
Factory Reset: A factory reset option is available to delete all custom vectors and test data, restoring the device to its original settings.

Safety Precautions

Only qualified and trained operators should use the TTRU1 after reading and understanding the instruction manual.
The TTRU1 and the Unit Under Test (UUT) should be considered sources of lethal electrical energy.
Observe all safety warnings on the TTRU1.
Treat all terminals of high-voltage power equipment as potential electric shock hazards.
Never connect the test equipment to energized equipment.
Always disconnect leads from the UUT before disconnecting them at the test set.
Wear safety glasses and insulated gloves when making circuit connections.
Hands, shoes, and floor/ground must be dry when making any connection to a powered line.
Only use NiMH and Alkaline AA batteries; do not mix battery types.
Do not use non-rechargeable batteries when the battery setting is set to NiMH.
Do not attempt to run tests while the TTRU1 is charging or connected to a PC.

Megger TTRU1 - Page 23

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