ANENG MH14 Digital Megohmmeter Insulation Resistance Meter User Manual

1. Overview

The ANENG MH14 Digital Megohmmeter is a professional instrument designed for testing the grounding resistance of electrical equipment. It features improved circuit, structure, and process compared to traditional grounding resistance testers, offering a beautiful and practical design, comprehensive functions, higher accuracy, and convenient, reliable operation. Its dust-proof and moisture-proof structure makes it suitable for field use. This device can be used to measure grounding resistance values for various power systems, power equipment, lightning protection equipment, and other grounding systems, as well as AC voltage.

2. Safety Precautions

This instrument is designed in accordance with IEC1010 Safety Standards. Please read the following precautions carefully before use:

1. Do not use the grounding resistance meter or measuring line if its appearance is damaged.
2. Avoid touching live conductors (DC60V, AC36V RMS or higher) to prevent electric shock.
3. Before measuring resistance, ensure the circuit is completely isolated from the power supply for accurate readings and personal safety.
4. Do not store the meter in high temperatures or direct sunlight to protect the liquid crystal display.
5. If the battery symbol ([BATTERY ICON]) is displayed, replace the batteries immediately. Remove batteries during long-term storage to prevent damage from battery fluid leakage.
6. Exercise extreme caution when measuring bare wires.
7. When powered by an external adapter, the internal battery is disconnected and cannot be charged. Ensure the power supply mode is selected correctly.

Grounding Resistance Test Requirements:

• AC working grounding: Resistance should not exceed 4Ω.
• Safe working grounding: Resistance should not be greater than 4Ω.
• DC working grounding: Resistance should be determined by specific computer system requirements.
• Lightning protection ground: Resistance should not exceed 10Ω.
• Jointed grounding of shielded systems: Resistance should not exceed 1Ω.

3. Unpacking Inspection & Package Contents

Carefully unpack the product and verify that all items listed below are present and in good condition. If any items are missing or damaged, please contact your dealer.

Package Contents:

1. 1 x Ground Resistance Meter (ANENG MH14)
2. 1 x Canvas Bag
3. 2 x Grounded Steel Brazing (Ground Studs)
4. 1 Set of Auxiliary Test Lines (Red 15m, Yellow 10m, Green 5m)
5. 1 Set of Simple Test Lines (Red 1.6m, Green 1.6m)
6. 1 x Instruction Manual
7. 1 x Product Certificate

4. Specifications

General Characteristics:

• Display: 90mm × 48mm LCD display, maximum display "1999".
• Over-range Indication: Only the highest digit displays "1" when the upper limit is exceeded.
• Power Supply: 8 x AA alkaline batteries (LR6 1.5V) (optional external power adapter option). Under-voltage indication when insufficient voltage.
• Power Consumption: <=800mW when testing no load.
• Operating Temperature: 0°C - 40°C, Relative Humidity: 30%-85% RH.
• Dimensions: 175 (L) × 110 (W) × 70 (D) mm.
• Weight: Approximately 750g (including battery).
• Design: Streamline design with anti-earthquake requirements.

Grounding Resistance Measurement:

Ground Voltage Measurement (50Hz~200Hz):

5. Operation Panel Instructions

Familiarize yourself with the controls and display of the ANENG MH14:

1. Power Adapter Jack: For connecting an optional external power adapter.
2. Model Face Card: Displays the model information.
3. LCD Display Window: Shows measurement readings and indicators.
4. Test Work Instructions Light: Illuminates when wiring is correctly connected during a test.
5. Test Button with Lock: Initiates a test. Can be locked for continuous measurement.
6. Self-locking Power Switch (POWER): Turns the device on/off.
7. Digital Hold Switch (HOLD): Freezes the current reading on the display.
8. Voltage Test Selection Switch: Selects the voltage measurement mode.
9. 2000Ω Range Resistance Selection Switch: Selects the 2000 Ohm range.
10. 200Ω Range Resistance Selection Switch: Selects the 200 Ohm range.
11. 20Ω Range Resistance Selection Switch: Selects the 20 Ohm range.
12. ACV Port: Voltage pole input.
13. E Port: Grounding pole input.
14. C Port: Current pole input.
15. P Port: Potential pole input.
16. Input Jack Face Card Instructions: Provides guidance for input connections.

6. Setup

Battery Installation:

The ANENG MH14 requires eight AA batteries (LR6 1.5V) for operation. Follow these steps to install them:

1. Locate the battery compartment on the back of the device.
2. Use a screwdriver to open the battery compartment cover.
3. Insert eight AA batteries, ensuring correct polarity (+/-).
4. Replace the battery compartment cover and secure it with the screw.

If the battery symbol appears on the display, replace the batteries. For long-term storage, remove the batteries to prevent leakage.

7. Operating Instructions

7.1. Battery Voltage Check:

After powering on the device, if the battery symbol is not displayed, the current power is sufficient. If the display flashes or the logo appears, please replace the battery.

7.2. Test Line Connection:

Ensure all test lead plugs are fully inserted into the test ends before measuring. Loose connections can lead to inaccurate measurement results.

7.3. Conventional Grounding Resistance Measurement:

DANGER: When measuring grounding resistance, a maximum of 50V AC voltage may be generated between the E-C or E-P terminals. Do not touch the test leads to avoid electric shock.

1. Test Wire Connection:
   Connect the auxiliary grounding rods P and C to the ground at a distance of 5 to 10 meters from the grounding object to be measured. Connect the green wire to the instrument's E terminal, the yellow wire to the P terminal, and the red wire to the C terminal.
2. Ground Preparation:
   Insert the auxiliary grounding rods into land with high water content. In dry land, depressions, or gravel, add water to keep the grounding hole moist. If concrete is encountered, lay the grounding rod flat, add water, and cover it with a wet towel before measuring.
3. Measurement Procedure:
   Start with the 2000 Ω range and press the "PRESS TEST" button. The backlight will illuminate. If the displayed value is too small, switch to the 200 Ω or 20 Ω range in order. The displayed value is the measured ground resistance. After testing, turn off the power switch to save power.

7.4. Ground Voltage Measurement:

1. Adjust the range selector switch to "EARTH VOLTAGE".
2. If the display shows a voltage value, it indicates the presence of grounding voltage in the system.
3. Confirm that the voltage value is below 10V. If it's above 10V, the grounding resistance measurement may be inaccurate. In such cases, power off the grounding device and lower the grounding voltage before measurement.

7.5. Simple Grounding Resistance Measurement:

This method is convenient when auxiliary ground rods cannot be used. It involves using a ground electrode with small impedance (e.g., metal water pipe, commercial power system grounding terminal, or building grounding terminal) instead of auxiliary grounding straps C and P.

1. Test Wire Connection:
   Connect the green wire to the instrument's E terminal and clamp it to the grounding body (e.g., electrical box ground terminal). Connect the red wire to the instrument's C terminal and clamp it to a suitable low-impedance ground electrode (e.g., fire hose, ensuring paint is removed for good contact).
2. Measurement Procedure:
   After connecting the lines, press the "PRESS TEST" button. The backlight will illuminate. If the displayed value is too small, switch to the 200 Ω or 20 Ω range. The displayed value is the measured ground resistance.

8. User Tips

• For accurate grounding resistance measurements, especially in dry conditions, moisten the soil around the ground rods.
• Always ensure good contact between the alligator clips and the test points by removing any paint or corrosion.
• When using the simple test method, ensure the chosen ground electrode has genuinely low impedance for reliable results.
• The "HOLD" function is useful for recording stable readings in challenging environments.

9. Maintenance

• Cleaning: Wipe the instrument with a soft, dry cloth. Do not use abrasive cleaners or solvents.
• Storage: Store the device in a cool, dry place, away from direct sunlight and extreme temperatures. Remove batteries if storing for extended periods.
• Protection: The device features a silicone sheath/ABS material for drop protection. While durable, avoid unnecessary impacts.

10. Troubleshooting

If your meter is not working properly, the following methods can help resolve common problems. If the issue persists, contact your service center or dealer.

Note: The measuring current is about 2mA. Even if an earth leakage circuit breaker is connected, the circuit breaker will not be operated.

The true grounding resistance value RX shall be calculated by the following formula:

RX = RE - re

• RE: Grounding resistance of common ground terminal (e.g., commercial power system)
• re: Instrument grounding resistance reading

11. Warranty & Support

This manual is subject to change without notice. The contents are considered correct at the time of publication. If you find any errors or omissions, please contact the manufacturer.

The company is not responsible for accidents or hazards caused by incorrect user operation. The functions described in this manual are not intended for special purposes beyond their stated use.

ANENG's professional after-sales team is available to assist you with any questions or issues during the use of the product. For specific product damage or operational problems, please contact ANENG customer service for timely solutions and assistance.