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Summary of Contents for MEGABRAS TM25t
- Page 1 TM25t High-frequency earth tester User manual Parts of this manual may differ from your equipment, depending on your country, hardware version and / or firmware and are subject to change without prior notice. © 2023 MEGABRAS. All rights reserved. 2023-08-01...
- Page 2 3.1. Battery / battery charger ..................9 3.1.1. Battery description ..................9 3.1.2. Battery status check ..................9 3.1.3. Recharge procedure ..................10 4. Connecting the TM25t ....................11 4.1. Equipment location ....................11 4.2. Auxiliary rods set up .....................11 5. Measuring ........................12 5.1.
- Page 3 TM25t 12. Technical specifications .....................20 13. Warranty ........................22...
- Page 4 Safety information z Before to use this instrument the User manual and Safety information must be read and understood z Safety procedures must be observed during the use of this equipment z The panel, terminals and connectors of the equipment must stay dry and clean z Only use accessories supplied by the manufacturer.
- Page 5 TM25t Symbols Caution, refer to User manual. Connector polarity indication. CAT IV Measuring category IV. Ground. Double insulation (Class II). USB (Universal Serial Bus). Back-light. Battery. Printer. Equipment complies with current EU Directives. The rubbish bin with a line through it means that in the European Union, the product must undergo selective disposal for the recycling of electric and electronic material, in compliance with Directive WEEE 2002/96/EC.
- Page 6 To make this kind of test feasible, which is of vital importance to ensure the transmission of the electrical power without interruptions, MEGABRAS TM25t grounding resistance tester for high frequency has been developed. This is the appropriate tool for a fast, safe and reliable grounding resistance measurement in each tower of a working line transmission, without disconnecting the ground wire.
- Page 7 TM25t TM25t is powered by a built-in LFP rechargeable battery. It is a rugged, easy to carry, resistant to the hard weather and geographical features of the tropical and high-mountain regions, that is why it is described as an excellent product for field works under the most severe environmental...
- Page 8 2. Control panel 2.1. Connections and items Power supply input Display USB interface Keyboard Current rod connector On/Off switch Potential auxiliary rod connector Thermal printer Tower support rod connector...
- Page 9 3.1. Battery / battery charger 3.1.1. Battery description The TM25t uses a built-in rechargeable LFP battery. This battery should be recycled at the end of its service life or placed in an appropriate site, in order to protect the environment.
- Page 10 This equipment has an internal battery charger with a smart circuit which adjusts the battery charge to the optimized parameters to ensure the maximum service life. To recharge the battery: z Check if the TM25t is off, and then connect it to the 110 V or 220 V mains supply (using the AC Adapter)
- Page 11 TM25t 4. Connecting the TM25t 4.1. Equipment location The equipment shall be placed as close as possible to the tower support where the grounding is located, and it will be connected to the instrument E terminal. 4.2. Auxiliary rods set up Auxiliary rods will be set up in the ground, making a straight line with the tower (point zero of measurements), perpendicular to the power transmission line.
- Page 12 5. Measuring 5.1. Selecting the type of measurement The TM25t measures grounding resistance with or without compensation of the inductive component. 5.1.1. Grounding resistance measurement z Select the grounding resistance measurement by pressing the key. When the equipment is switched on, this function is automatically selected...
- Page 13 TM25t Note: If the system tuning is not obtained (normally because the inductance of the grounding systems is not significant), this will be shown in the display. If the test is printed, the message “Undefined” for the values R and C, with L= 0 will be displayed.
- Page 14 5.2. Looking for the potential profile flat area After getting the first Grounding Resistance Value, it is necessary to obtain the greatest amount of points to trace the potential profile curve. In order to do that, the potential rod (probe) should be always set up perpendicular to the traced line, in several intermediate points between the unknown electrode and the current rod, so as to obtain the kind of curve showed below.
- Page 15 TM25t 6. Abnormalities indications on the display If the TM25t identifies any abnormality causing the measurements to be excessively inaccurate, or not possible at all, a warning message will be shown on the display, allowing the operator to identify and correct the problem.
- Page 16 If it is suspected that the measurement is affected by this condition, the grounding resistance of each auxiliary rod should be measured with a conventional earth tester so as to avoid reporting wrong values. 7. Auto power-off The TM25t auto-turns off after 15 minutes of inactivity.
- Page 17 If there is an available Internet connection, Windows will silently connect to the Windows Update website and install any suitable driver it finds for the device. If no suitable driver is found, you need to download it from www.megabras.com/megalogg, run the executable “usb-install.exe” and click in “Install”.
- Page 18 9. Remote control Use your Android™ smartphone or tablet to fully control this equipment with greater convenience and resources. Point your device to the QR-Code to download the App and enjoy its unique features! It’s free! • Android, Google Play and the Google Play logo are trademarks of Google LLC •...
- Page 19 TM25t 11. Cleaning z Before cleaning the equipment, disconnect the equipment from the mains and disconnect all cables z After cleaning and before plugging in again, make sure that the equipment is completely dry to avoid risk of electric shock and malfunction of the instrument The panel, terminals and connectors of the equipment must stay dry and clean.
- Page 20 12. Technical specifications Measurement ranges 0 - 300 Ω Operation frequency 25.000 Hz Test current 20 mA automatic Inductive component Through bank of capacitors integrated to the equipment compensation Maximum capacity: 4.2 μF Resolution: 10 nF Measurement accuracy ± 2.5 % of reading ± 1 digit Display Alphanumerical LCD display, 4 lines / 20 characters (Big Number)
- Page 21 TM25t Accessories • 8x 50 cm long steel core rods with copper coating • 6x 2 m cables for interconnection of extra auxiliary rods • Rod extractor • 70 m shielded cable • 50 m shielded cable • 30 m cable to current rod •...
- Page 22 13. Warranty MEGABRAS warrants the products for two years from date of shipment. We will repair, without charge, any defects due to faulty materials or workmanship. For warranty repair information, visit our website www.megabras.com. This warranty does not apply to accessories or damage caused where repairs have been made or attempted by others.
- Page 23 TM25t...
- Page 24 MEGABRAS INDÚSTRIA ELETRÔNICA LTDA. Rua Gibraltar, 172 - Santo Amaro CEP 04755-070 - São Paulo - SP - Brazil Phone: +55 (11) 3254-8111 / +55 (11) 5641-8111 - Fax: +55 (11) 5641-9755 www.megabras.com...
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