"Compressor Megger Test Fail लेकिन Power On करने पर Start हो जाता है? | MK Technical Solutions"

Описание: Compressor Megger Test Fail लेकिन Power On करने पर Start क्यों होता है?

Welcome to MK Technical Solutions! In this video, we will explain why a compressor fails the megger test but still starts when powered on. Understanding insulation resistance, megger testing, and compressor faults is essential for troubleshooting HVAC and refrigeration systems.


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1. What is a Megger Test & Why is it Important?

A megger test (megohmmeter test) is used to measure insulation resistance in electrical components like compressor windings, motors, and transformers. It helps detect:

✔ Insulation breakdown
✔ Moisture inside windings
✔ Short circuits or leakage currents
✔ Deterioration of motor insulation

A failed megger test usually indicates a problem with the compressor winding insulation, which can lead to electrical faults or motor failure.


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2. Why Does the Compressor Start Even After Failing the Megger Test?

If a compressor fails the megger test but still starts, the following reasons could be responsible:

✔ 1. Moisture in Windings:

If the compressor has absorbed moisture, it may reduce insulation resistance.

When power is applied, heat may evaporate the moisture, temporarily allowing the compressor to run.


✔ 2. Partial Insulation Breakdown:

The insulation may be weak but not completely damaged.

The compressor might still function for some time before failing completely.


✔ 3. Low-Voltage Megger Test vs. High Operating Voltage:

A megger applies 500V or 1000V to test insulation, whereas the compressor may run at a higher voltage.

At operating voltage, the compressor may overcome minor insulation weaknesses.


✔ 4. Contaminated or Dirty Windings:

Oil, dust, or dirt on windings can cause false readings in a megger test.

Cleaning and drying the compressor may help.


✔ 5. Internal Short but Still Functional:

A minor short between windings may not immediately stop the compressor but will cause overheating and eventual failure.


✔ 6. Winding Resistance Still Within Operating Range:

If the resistance is low but within the operating limit, the compressor can still function.

However, it indicates potential long-term failure.



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3. How to Confirm if the Compressor is Safe to Use?

Step 1: Check Insulation Resistance Again

Use a megger at 500V or 1000V and measure resistance between:
✔ Winding to Ground (Earth)
✔ Winding to Winding (U-V-W phases)


✅ Safe Readings: Above 1 MΩ (Megaohm)
⚠️ Dangerous Readings: Below 0.5 MΩ


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Step 2: Measure Running Current

Use a clamp meter to check the compressor's ampere draw while running.

Compare it with the rated current on the compressor nameplate.


✅ Safe Current: Within ±10% of rated value
⚠️ High Current: Indicates insulation breakdown or internal damage


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Step 3: Perform a High-Potential (Hi-Pot) Test

A Hi-Pot test applies a higher voltage to detect insulation breakdown.

Only a qualified technician should perform this test.



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Step 4: Inspect for Overheating & Noise

If the compressor is overheating or making noise, it may indicate internal damage.

If no abnormal signs are found, the compressor may still be

6. FAQs – Compressor Megger Test & Start-Up Issues

Q1: What should be the ideal megger test reading for a compressor?

✅ A safe reading is above 1 MΩ (Megaohm).
⚠️ A reading below 0.5 MΩ indicates insulation failure.

Q2: Can a compressor run with a failed megger test?

✔ Yes, it may still start due to partial insulation damage or moisture, but it is risky.

Q3: How do I fix low insulation resistance in a compressor?

✔ Dry the compressor, clean windings, and apply insulation varnish to restore resistance.

Q4: What happens if I keep running a compressor with insulation failure?

⚠️ It can lead to motor burnout, short circuit, or complete failure over time.

Q5: How often should I perform a megger test on a compressor?

✔ It is recommended to test insulation every 6-12 months as part of preventive maintenance.


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7. Why Subscribe to MK Technical Solutions?

At MK Technical Solutions, we provide step-by-step HVAC troubleshooting guides to help technicians diagnose and fix electrical and mechanical faults in compressors, chillers, and air conditioning systems.

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Conclusion

A compressor failing the megger test but still starting can indicate moisture, partial insulation damage, or an inaccurate test result. By following proper diagnostic steps, you can determine whether it is safe to continue using the compressor or if a replacement is needed.

✅ Regular testing, preventive maintenance, and monitoring running conditions can help extend the lifespan of your compressor.

📌 For more HVAC troubleshooting tips, subscribe to MK Technical Solutions!