Victor Digital Earth Resistance Tester

1. Introduction

The Victor Digital Earth Resistance Tester is a specialized instrument designed for precise on-site measurement of earth resistance, soil resistivity, and earth voltage. It incorporates advanced digital processing technology, offering high accuracy, stability, and reliability for long-term measurements. The robust, waterproof (IP65 rated), anti-collision, and anti-drop casing makes it suitable for outdoor construction sites.

This tester is widely used in various fields including electrical power, telecommunications, meteorology, construction, lightning protection, and industrial electrical equipment. It features a large LCD display with white backlight for clear visibility, data storage capabilities (up to 400 groups), and real-time monitoring via software.

A unique wire resistance calibration function enhances accuracy, especially for low-value ground resistance measurements, by compensating for test line resistance variations and poor contact issues.

Figure 1: Victor Digital Earth Resistance Tester (Model 4105C)

2. Safety Precautions

Failure to follow these safety precautions may result in injury or damage to the instrument.

• Always read this user manual thoroughly before operating the instrument.
• Comply with all operating cautions and warnings provided in this manual.
• The tester is designed according to IEC61010 safety requirements.
• USB Interface Warning: The USB interface and internal circuits are non-isolated. Never connect the computer when voltage is being tested, as this may burn out the instrument or cause electric shock. Always unplug the voltage test line from the meter before connecting the USB data cable to a computer for data transfer.
• Pay close attention to all words and symbols marked on the tester.
• Ensure the tester and accessories are in good condition before use. Do not use if any part of the testing wires or insulation layer is damaged, naked, or broken.
• During measurement, avoid touching bare conductors and circuits under test.
• Always confirm the position of the FUNCTION rotary switch before measurement.
• Ensure connector plugs of leads are securely inserted into the tester interface.
• Do not supply over 600V grounding voltage between the testing device and interface, as it may damage the meter.
• Do not measure in inflammable environments, as sparks may cause explosions.
• Discontinue use if the outer shell or testing wires are broken, exposing metal.
• Avoid prolonged storage under high temperature, humidity, condensation, or direct sunlight.
• If the instrument becomes wet, store it only after it has completely dried.
• Always remove the test wire from the meter before charging.
• The rechargeable battery pack must only be charged with the designated charger.
• The meter has an automatic shutdown function to conserve battery.
• If the battery low voltage symbol appears, charge the battery immediately.
• If the tester will not be used for a long period, charge the battery every 1-2 months.
• Observe the specified measuring range and usage environment for the Tester.
• Only authorized personnel should perform use, disassembly, calibration, and repair of this tester.
• If the instrument becomes dangerous to use, stop operation immediately, seal it, and have it handled by an authorized institution.

3. Product Components and Accessories

The Victor Digital Earth Resistance Tester package typically includes the following items:

• Main unit (Tester)
• Grounding pins (Auxiliary grounding rods)
• Standard test leads (Red, Black, Yellow, Green)
• Simple test leads (Red, Black)
• USB cable
• Instrument package (carrying bag)
• Charger
• Instruction manual
• Monitoring Software Disk (CD) (for some models)
• Current clamp (for Model 6415A)

Figure 2: 4105C Model and Included Accessories

Figure 3: 4106C Model and Included Accessories

Figure 4: 6415A Model and Included Accessories (with Current Clamp)

4. Device Structure and LCD Display

4.1 Tester Structure Overview

The main unit features a robust casing with a hinged lid that reveals the LCD display, control panel, and connection interfaces.

1. Charge interface
2. USB Interface
3. E interface: Earth electrode
4. ES interface: Auxiliary earth electrode
5. P(S) interface: Voltage electrode
6. C(H) interface: Current electrode
7. TEST button
8. LCD display screen
9. Rotary switch (FUNCTION selector)
10. Button area (HOLD, READ, AL, SET)
11. Simple test wires
12. Auxiliary grounding rod
13. Test wires (standard)

4.2 LCD Display Elements

The super-large LCD provides clear readings and indicators:

• Test progress bar: Dynamically displays the progress of the test.
• Alarm indicator symbol: Flashes when the measurement value exceeds the set alarm value.
• Exceed voltage symbol: Appears if measured voltage exceeds 30V, indicating a safety concern.
• AC indicator: Indicates AC measurement mode.
• Data hold symbol (HOLD): Indicates data is held on display.
• Data access symbol (READ): Indicates data access mode.
• Interference signal symbol (NOISE): Appears if interference voltage exceeds 5V.
• Low battery symbol: Indicates battery voltage is below 7.5V.
• Group number: Displays the group number of stored data and countdown.
• Interference electrode symbol: Appears if electrode interference voltage exceeds 5V.
• Test data: The primary measurement reading.
• Voltage unit symbol: V.
• Resistance/Resistivity unit symbol: Ω, kΩ, Ωm, kΩm, m.

5. Technical Specifications

The following table details the technical specifications for the Victor Digital Earth Resistance Tester models:

Figure 5: Detailed Technical Specifications

General Specifications:

For more detailed specifications and functional parameters, please refer to the images below:

Figure 6: Functional Parameters Overview

6. Setup and Operation

6.1 Battery Installation and Charging

• The instrument uses a DC 7.4V 2600mAh rechargeable lithium battery.
• When the low battery symbol () appears on the LCD, charge the battery immediately.
• Connect the charger to the charging interface. The charger indicator will be red during charging and turn green when fully charged.
• Ensure the meter is in the OFF state before connecting the charger.
• For prolonged storage, charge the battery every 1-2 months to maintain its health.

6.2 Switching On/Off

To turn the device ON, rotate the rotary switch from the "OFF" position to the desired function (e.g., REARTH, pEARTH, VEARTH). To turn the device OFF, rotate the rotary switch back to the "OFF" position. The meter will automatically power down after 10 minutes of inactivity.

6.3 Measurement Principles

• Earth Voltage Measurement: Uses an average value rectification method.
• Earth Resistance Measurement: Employs a rated current change-pole method. An AC rated current (I) flows between the E (earth electrode) and C(H) (current electrode). The potential difference (V) between E and P(S) (voltage electrode) is measured, and resistance (R) is calculated as R=V/I.
• Soil Resistivity Measurement: Utilizes the 4-pole Wenner method. The formula p=2πaR (Ωm) is used, where 'a' is the electrode distance and 'R' is the resistance between P(S)-ES.

6.4 Measurement Methods

Always ensure the grounding voltage is below 20V before performing earth resistance measurements. If the NOISE symbol appears, power off the grounding device and retest.

6.4.1 4-Wire Precise Earth Resistance Measurement

• This method eliminates the influence of contact resistance and test line resistance, providing higher precision.
• Connect the E, ES, P(S), and C(H) interfaces of the tester to the corresponding points on the grounded electrode and auxiliary grounding rods.
• The auxiliary grounding rods (P(H) and C(H)) should be buried in the ground in a straight line, typically 5-20m apart.
• The distance between the grounding body (E) and the current pole (C(H)) should be at least 5 times the subsurface depth (h) or 5 times the buried ground electrode length (d).
• Do not entangle test leads.

Figure 7: 4-Wire Measurement Setup (Model 6415A)

6.4.2 3-Wire Earth Resistance Measurement

• In this method, the ES and E interfaces are short-circuited.
• This method does not eliminate the influence of line resistance or contact resistance between the meter and test line/auxiliary ground rod.
• Ensure the oxide layer on the surface of the grounded body is removed before measurement.
• After connecting wires, rotate the rotary switch to "REARTH" and press "TEST".
• After the test, press "SET" to check the auxiliary current pole (rC) and voltage pole (rP) resistance values.

Figure 8: 3-Wire Measurement Setup (Model 4106C)

6.4.3 2-Wire Simple Measurement

• This method does not use an auxiliary grounding rod. An existing grounding electrode with the lowest resistance value (e.g., metal ground pipe, fire hydrant, commercial power system grounding) is used as the auxiliary grounding pole.
• The C(H)-P(S) and E-ES interfaces are shorted.
• Warning: If using commercial power system grounding, confirm its integrity. Otherwise, circuit breakers may trip, posing a danger.
• Choose a grounding body with a small resistance value (Re) to ensure the meter reading is closer to the true value.

Figure 9: 2-Wire Measurement Setup (Model 4105C)

6.4.4 Soil Resistivity Measurement

• Rotate the FUNCTION rotary switch to "pEARTH".
• Long press "SET" (approx. 3 seconds) to enter setting mode. Use "SET" to move the cursor and "" or "" buttons to change the 'a' value (electrode distance, range 1m-100m). Long press "SET" again to save and return to test mode.
• Press "TEST" to start the measurement. The LCD will show a countdown and progress bar.
• After the test, press "SET" to view the auxiliary current pole (rC) and voltage pole (rP) resistance values.

6.4.5 Earth Voltage Measurement

• Rotate the rotary switch to "VEARTH".
• Connect the meter, auxiliary grounding rods, and testing wires.
• The LCD will display the measured earth voltage.
• Warning: Do not connect the meter's test interfaces to commercial power lines (L, N), as this may cause current leakage or trip circuit breakers.

6.5 Data Management

• Data Lock/Storage: In test mode, press "HOLD" to lock the displayed data. The "HOLD" and "MEM" symbols will appear, and the data will be automatically stored with serial numbers. If storage is full, "FULL" will be displayed. Press "HOLD" again to unlock.
• Data Access/Delete: Long press "READ" to enter data access mode. Use "" or "" buttons to select the data group number. Press "SET" to view rC, rP, and 'a' values for earth resistance/soil resistivity data. Press "CLR" to enter data delete mode, then select "YES" or "NO" to delete all stored data. Note: Deleting data is irreversible.
• Data Upload: Connect the tester to a computer via the USB communication cable. Turn on the tester and run the monitoring software. Once the software detects the serial port and successful connection, you can read and transfer historical data.

6.6 Bluetooth Software Operation (for compatible models)

This software is a mobile APP for Android systems (version 4.0 and above) designed to connect with double-clamp multi-function earth resistance testers. It does not support other Bluetooth devices.

• Installation: Scan the QR code (if provided with your product) to download the APP. Grant necessary permissions during installation.
• Bluetooth Connection: In the APP's "Bluetooth Settings", turn on Bluetooth, then search for available devices. Select the tester's Bluetooth name to connect.
• Data Acquisition: The APP allows sending test commands, batch data acquisition (history data from the tester), and viewing/analyzing historical data.

7. Maintenance

7.1 Cleaning and Storage

• Keep the instrument clean and dry. Wipe the casing with a soft, damp cloth. Do not use abrasive cleaners or solvents.
• Store the tester in a cool, dry place, away from direct sunlight, high temperatures, and high humidity.
• If the instrument becomes wet, ensure it is completely dry before storing.

7.2 Battery Care

• Charge the battery regularly, especially if the instrument is not used for extended periods (every 1-2 months).
• Only use the designated charger.
• Do not replace the battery in flammable areas or during measurement.
• Pay attention to battery polarity and specifications. Do not mix new and used batteries.
• If the tester's enclosure is wet, do not open the battery cover.
• Dispose of used batteries at designated collection points.

8. Troubleshooting

9. User Tips

• For the most accurate low-value ground resistance measurements, utilize the 4-wire method whenever possible, as it effectively compensates for lead resistance and contact resistance.
• When performing soil resistivity measurements, ensure the electrode distance 'a' is significantly greater than the embedding depth 'h' (a > 20h) for reliable results.
• While this device is primarily an Earth Resistance Tester, it does not typically measure electrical continuity in the same way a standard multimeter would. Its functions are focused on grounding resistance, soil resistivity, and earth voltage.
• Regularly check the condition of your test leads and grounding pins. Damaged insulation or corroded contacts can lead to inaccurate readings and safety hazards.
• Always keep the monitoring software updated to ensure compatibility and access to the latest features for data analysis and reporting.

10. Warranty and Support

The company reserves the right to change specifications and designs described in this manual without notice and without obligations. This user manual cannot be used as a reason to use the product for special purposes.

For technical support, service, or warranty inquiries, please contact your vendor or an authorized service center. Refer to the official product documentation or the seller's website for specific warranty terms and conditions.

An official user manual in PDF format is available for download: Download User Manual (PDF)

11. Application Scenarios

The Victor Digital Earth Resistance Tester is suitable for a wide range of applications, including:

• Electricity: Testing grounding systems in power plants and substations.
• Oilfield: Ensuring proper grounding in oil and gas facilities.
• Lightning Protection: Verifying the effectiveness of lightning protection systems.
• Architecture: Assessing grounding for building structures.
• Telecommunications: Maintaining grounding for communication towers and equipment.
• Industrial Electrical: General grounding checks in industrial settings.

Figure 10: Common Application Scenarios