1. Introduction
This manual provides essential instructions for the safe and effective operation, maintenance, and troubleshooting of the Megger MIT515-US 5kV Insulation Tester. The MIT515-US is a robust, portable instrument designed for measuring insulation resistance in high-voltage electrical systems, including cables, transformers, motors, and generators. It offers a range of test voltages up to 5kV and advanced diagnostic capabilities.
2. Safety Information
WARNING: Always read and understand all safety instructions before operating the Megger MIT515-US. Failure to follow these instructions can result in serious injury or death, and damage to the equipment.
- The MIT515-US is rated for CAT IV 600 V. Always adhere to safety standards for high-voltage testing.
- Ensure the instrument and test leads are in good condition before use. Do not use if damaged.
- Always connect the ground lead first and disconnect it last.
- Do not touch test leads or the circuit under test during operation. High voltages are present.
- Verify that the circuit under test is de-energized before connecting the tester, unless performing live voltage measurements with appropriate precautions.
- Use only Megger-approved accessories and replacement parts.
3. Product Overview
The Megger MIT515-US is a compact and lightweight insulation resistance tester featuring an intuitive interface and robust construction. Key components include the display, control buttons, rotary switches for test selection, and safety-rated terminals.
Figure 1: Megger MIT515-US Front Panel
This image displays the front panel of the Megger MIT515-US 5kV Insulation Tester. Visible elements include the digital display showing test voltage (5105 V), resistance (10 TΩ), and current (-0.1 nA), along with a timer (2:12 ms). The top section features red (+) and black (-) test terminals, and a blue GUARD terminal, all rated CAT IV 600V. On the right, there's an 'OK' button cluster for navigation and a red 'TEST' button. The lower left has a rotary switch for IR, DAR, and PI tests. The lower right has a rotary switch for selecting test voltages: OFF, 250V, 500V, 1kV, 2.5kV, and 5kV. The device is housed in a rugged, grey and black case.
3.1 Key Features
- Test Voltages: Selectable from 250 V to 5 kV.
- Resistance Measurement: Up to 10 TΩ.
- Diagnostic Tests: Polarization Index (PI), Dielectric Absorption Ratio (DAR), Dielectric Discharge (DD), Step Voltage (SV), and Ramp Test.
- Safety Rating: CAT IV 600 V on all terminals.
- Power: Rechargeable Lithium-ion battery with rapid charge capability, also operates from line power.
- Display: Analog/digital display for clear readings.
- Guard Terminal: Industry-best guard terminal performance for enhanced accuracy.
4. Setup
4.1 Charging the Battery
The MIT515-US is equipped with a Lithium-ion battery. Before initial use, fully charge the battery. Connect the provided power cord to the instrument's power input and then to a suitable AC power source. The battery status indicator on the display will show charging progress. A full charge typically takes 2.5 hours, providing approximately 1 hour of testing after a 0.5-hour charge.
4.2 Connecting Test Leads
- Ensure the MIT515-US is powered off and the test voltage selector is in the 'OFF' position.
- Connect the red test lead to the positive (+) terminal on the instrument.
- Connect the black test lead to the negative (-) terminal on the instrument.
- For applications requiring a guard circuit to minimize surface leakage currents, connect the blue guard lead to the 'GUARD' terminal.
- Connect the test leads to the equipment under test, ensuring proper polarity and secure connections. Always connect the ground lead first to the equipment under test.
5. Operating Instructions
5.1 Powering On/Off
To power on the instrument, rotate the test voltage selector switch from 'OFF' to any desired voltage setting. To power off, rotate the switch back to 'OFF'.
5.2 Performing an Insulation Resistance (IR) Test
- Connect the test leads to the circuit under test as described in Section 4.2.
- Rotate the diagnostic test selector switch to 'IR'.
- Select the desired test voltage (e.g., 500V, 1kV, 2.5kV, 5kV) using the voltage selector switch.
- Press and hold the red 'TEST' button to initiate the test. The instrument will apply the selected voltage and display the insulation resistance.
- Release the 'TEST' button to stop the test. The instrument will automatically discharge the circuit.
- Record the displayed resistance value.
5.3 Performing Diagnostic Tests (PI, DAR, DD, SV, Ramp)
The MIT515-US offers advanced diagnostic tests for a more comprehensive assessment of insulation quality.
- Polarization Index (PI) and Dielectric Absorption Ratio (DAR): Select 'PI' or 'DAR' on the diagnostic test selector. These tests automatically measure resistance at specific time intervals (e.g., 30s, 60s, 10min) and calculate the ratio. Follow on-screen prompts.
- Dielectric Discharge (DD): Select 'DD' on the diagnostic test selector. This test measures the current discharged from the insulation after a period of charging, indicating insulation degradation.
- Step Voltage (SV) and Ramp Test: These tests involve applying increasing voltage steps or a continuously rising voltage to detect insulation weaknesses that might not be apparent at a single test voltage. Refer to the on-screen menu and 'OK' button for navigation and parameter setup.
5.4 Voltmeter Function
The instrument includes a dedicated voltmeter function (30 V to 660 V) with frequency measurement. This allows users to check for induced voltages in a circuit before performing insulation tests. Select the 'V' position on the voltage selector switch to activate this function.
6. Maintenance
6.1 Cleaning
Clean the instrument's exterior with a damp cloth and mild detergent. Do not use abrasive cleaners or solvents. Ensure no moisture enters the instrument.
6.2 Battery Care
To prolong battery life, avoid fully discharging the battery frequently. Store the instrument with a partial charge if it will not be used for an extended period. If the battery is fully discharged, the unit can still operate from line power while charging.
6.3 Test Lead Inspection
Regularly inspect test leads for any signs of damage, such as cuts, cracks, or frayed insulation. Replace damaged leads immediately with Megger-approved replacements to maintain safety and measurement accuracy.
7. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| Instrument does not power on. | Battery discharged or power cord not connected. | Charge the battery or connect to line power. Ensure power cord is securely connected. |
| No reading during test. | Test leads not properly connected or circuit is open. | Check all test lead connections. Verify the circuit under test is complete. |
| Inaccurate readings. | Surface leakage current, damaged leads, or incorrect test setup. | Use the guard terminal to eliminate surface leakage. Inspect and replace damaged leads. Review test setup procedures. |
| Error message on display. | Internal fault or operational error. | Refer to the specific error code in the full user manual (if available) or contact Megger support. |
8. Specifications
- Model: MIT515-US (1001-936)
- Test Voltage: 5.0 kV, 2.5 kV, 1.0 kV, 500 V, 250 V; 10 V steps from 50 V to 1 kV; 25 V steps from 1 kV to max. test voltage.
- Resistance Measurement Range: Up to 10 TΩ for 5 kV models.
- Accuracy: 5% up to 1 TΩ at 5 kV.
- Safety Rating: CAT IV 600 V on all terminals.
- Operating Temperature: -4°F to +122°F (-20°C to +50°C).
- Power Source: Rechargeable Lithium-ion battery and line power.
- Battery Charge Time: 2.5 hours for full charge (0.5 hour charge for 1 hour testing).
- Dimensions: Approximately 17.3 x 13.9 x 12.8 inches (Package Dimensions).
- Weight: Approximately 1 Pound (Item Weight).
9. Warranty and Support
For warranty information, technical support, or service, please contact Megger customer service or visit the official Megger website. Keep your purchase receipt as proof of purchase for warranty claims.
