Megger MIT400/2 Insulation & Continuity Tester

Introduction

This user manual provides essential information for the safe and effective operation of the Megger MIT400/2 Insulation & Continuity Tester, model 1006-719. This versatile instrument is designed for a wide range of applications, including electrical installations, cable testing, motor testing, automotive diagnostics, ESD measurements, panel building, avionics, and general maintenance.

The MIT400/2 features enhanced insulation testing with feedback-controlled test voltages, limiting over-voltage to 2%. It also offers a variable voltage range from 250 V to 1000 V in 10 V steps for specific application requirements. Continuity testing is significantly faster, with an autoranging function from 0.01 ̑ to 1.0 M̑, and retains 200 mA and 20 mA test options. The redesigned unit boasts an over-moulded case for increased protection and an IP54 weatherproof rating.

Safety Information

Always adhere to local and national safety regulations when using electrical test equipment. Failure to follow these safety guidelines may result in injury, damage to the instrument, or damage to the equipment under test.

• Ensure the instrument is in good working condition before use.
• Do not use the tester if it appears damaged or if the battery compartment is open.
• Always disconnect power from the circuit under test before making connections for insulation or continuity measurements.
• Use only test leads supplied or recommended by Megger.
• Be aware of live circuits and potential shock hazards.
• Do not operate the instrument in wet conditions or explosive atmospheres.
• Refer to the full safety instructions in the comprehensive manual for detailed precautions.

Product Overview

Figure 1: Front view of the Megger MIT400/2 Insulation & Continuity Tester, showing the display, control buttons, and rotary selector switch.

The Megger MIT400/2 features a clear digital display for readings and settings. Key controls include:

• Display: Shows insulation resistance (G̑), voltage (V), and continuity (̑) readings. Includes an analog arc for quick visual indication.
• TRMS Button: Toggles True RMS measurement mode.
• Backlight Button: Activates or deactivates the display backlight for improved visibility in low-light conditions.
• Sound Button: Controls audible alerts, such as continuity beepers.
• TEST Button (Yellow): Initiates an insulation or continuity test.
• Lock Button (Red): Locks the test button for continuous testing, useful for hands-free operation during insulation tests.
• Rotary Selector Switch: Used to select the desired measurement function:
  • M̑ (Insulation Resistance): Selects insulation test voltages (e.g., 250V, 500V, 1kV).
  • V (Voltage): Measures AC/DC voltage.
  • OFF: Powers off the instrument.
  • ̑ (Continuity): Measures resistance and performs continuity checks.
  • Wrench/Tool Icon: Indicates a special function or setting mode.

Setup

Battery Installation

The MIT400/2 is powered by 6 AA batteries. The battery compartment is located at the rear of the unit and features separate fuse access.

1. Ensure the instrument is switched to the OFF position.
2. Locate the battery compartment cover on the back of the unit.
3. Unscrew or unlatch the cover and remove it.
4. Insert 6 AA batteries, observing the correct polarity indicated inside the compartment.
5. Replace the battery compartment cover and secure it firmly.

Initial Checks

Before first use, or after battery replacement, perform a quick functional check to ensure the unit powers on and the display is clear.

Operating Instructions

Insulation Testing (M̑)

The MIT400/2 offers insulation testing up to 1000 V and 200 G̑ range with stabilized test voltage.

1. Turn the rotary selector switch to the desired M̑ voltage range (e.g., 250V, 500V, 1kV). A variable range allows intermediate voltages from 250 V to 1000 V in 10 V steps.
2. Connect the test leads to the circuit or component under test, ensuring proper polarity.
3. Press and hold the yellow TEST button to initiate the test. The display will show the insulation resistance.
4. For continuous testing, press the red Lock button after pressing TEST. Press TEST again to unlock.
5. Release the TEST button to stop the measurement.

Continuity Testing (̑)

The instrument provides fast autoranging continuity testing from 0.01 ̑ to 1.0 M̑, with 200 mA and 20 mA test options.

1. Turn the rotary selector switch to the ̑ position.
2. Connect the test leads to the circuit or component.
3. The instrument will automatically display the resistance. If continuity is detected within the set threshold, an audible beep may sound (if enabled).
4. Use the Sound button to toggle the continuity beeper.

Voltage Measurement (V)

Measure AC or DC voltage.

1. Turn the rotary selector switch to the V position.
2. Connect the test leads across the voltage source.
3. The display will show the measured voltage.
4. Press the TRMS button to toggle between True RMS and average sensing for AC voltage measurements.

Display Backlight

Press the Backlight button to illuminate the display for better readability in dimly lit environments. Press again to turn off.

Maintenance

Cleaning

Clean the instrument regularly with a damp cloth and mild detergent. Do not use abrasive cleaners or solvents. Ensure the unit is dry before storage or use.

Battery Replacement

When the low battery indicator appears on the display, replace all 6 AA batteries as described in the "Battery Installation" section. Always use fresh, high-quality batteries.

Fuse Access

The MIT400/2 features separate fuse access within the battery compartment. Refer to the full service manual for fuse specifications and replacement procedures.

Calibration

Your Megger MIT400/2 is calibrated prior to shipment and comes with a new NIST-traceable calibration certificate with data. This ensures the instrument meets manufacturer's specifications and is ready for use, meeting most quality system standards. Regular calibration by qualified personnel is recommended to maintain accuracy.

Troubleshooting

• No Display/Unit Not Powering On: Check battery installation and ensure batteries are fresh. Verify the rotary switch is not in the OFF position.
• Inaccurate Readings: Ensure test leads are properly connected and not damaged. Verify the correct measurement function is selected. Consider recalibration if issues persist.
• Continuity Beeper Not Working: Check if the sound function is enabled using the Sound button.
• Test Button Not Responding: Ensure the unit is not in a locked state (check the red lock indicator).

For more complex issues, contact Megger customer support or a qualified service technician.

Specifications

Warranty and Support

For information regarding product warranty, technical support, or service, please contact Megger directly. Refer to the official Megger website or your purchase documentation for contact details and warranty terms specific to your region.

Manufacturer: Megger