Description
Testing of the power transmission towers grounding (G) quality poses a serious problem as they are all electrically interconnected by means of Ground Wires which act as lightning rods, protecting the lines from atmospheric discharges. Due to the existence of this connection, any attempt to measure a tower grounding (G) resistance using a conventional earth meter leads to wrong results as what is really being measured is all the shunt towers grounding (G) resistance (or, more precisely, its impedance at low frequency).
To make this kind of test feasible, which is of vital importance to ensure the transmission of the electrical power without interruptions, TENTECH TM25t grounding resistance meter 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.
Its operation is based on the use of a high-frequency measurement current (25 kHz), for which ground wire inductive impedance - taking into account a typical length span - is reasonably high, making it possible to reduce the effect of the adjacent towers under measurement. The equipment only measures the ground resistance of the surveyed tower, including its base. The extensive G systems, such as meshes, buried wires, metal pipes, etc, are measured only considering the closest section to the connection point, so that the measured value represents the performance against a pulse signal similar to an atmospheric discharge. Thus, values that better represent the system capacity to ground lightning currents than the ones obtained with low frequency conventional equipments, even when disconnecting the ground wire, are obtained. TM25t is a strong equipment, 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 conditions.
Technical specifications
Measurement ranges
0 - 300 Ω
Operation frequency
25,000 Hz
Test current
20 mA automatic
Inductive component compensation
• Through bank of capacitors integrated to the equipment
• Maximum capacity: 4.2 μF
• Resolution: 10 nF
Measurement accuracy
± 2.5 % of reading ± 1 digit
Max. earth resistance of auxiliary rods
2,000 Ω (current rod)
2,000 Ω (voltage rod)
Display
Alphanumerical LCD display, 4 lines / 20 characters (Big Number)
Printer
Built-in thermal printer
Built-in memory
It allows for the storage of 2,000 tests readings in its internal NVRAM memory
Protocol
Modbus
USB
For configuration, control and download the stored values
Bluetooth
For configuration, control and download the stored values
Overvoltage protection
CAT IV - 300 V
Safety
IEC 61010-1
Desktop Software (PC/Notebook)
TLogger software: for remote control, allowing to configure, run tests and generate reports
Android App (Smartphone/Tablet)
TENTECH Remote Control app: for remote control, allowing to configure, run tests and generate reports
IP rating
IP65 (with closed lid)
Operating temperature
14 °F to 122 °F (-10 °C to 50 °C)
Storage temperature
-13 °F to 158 °F (-25 °C to 70 °C)
Humidity
95 % RH (non condensing)
Power supply
Internal rechargeable battery (LFP 12 V 6000 mA)
Battery charger
12 V - 2 A
Equipment weight
Approx. 10.80 lb (4.9 kg)
Dimensions
13.6" x 10.7" x 6.3" (345 x 272 x 159 mm)
