Zana ya Uhandisi Isiyolipisha

Mkamataji wa Ukinzani wa Insulation wa Motor (Megger)

Tafsiri matokeo ya mtihani wa megger kulingana na IEEE Std 43. Kokotoa upinzani wa insulation wa chini unaokubali, thamani zilizorekebishwa kwa joto, faharasa ya polarization, na mapendekezo ya mwelekeo.

IEEE 43 Megger Test Faharasa ya Polarization

1-Minute IR Reading (MΩ)

10-Minute IR Reading (MΩ, hiyari kwa PI)

Upinzani Uliokadiria wa Motor (V)

Joto la Mtihani (°C)

Umri / Hali ya Motor

Darasa la Insulation

Interpretation

Tathmini ya Jumla

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Chini Inayokubali (IEEE 43)

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IR iliyorekebishwa @ 40°C

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Sababu ya Kubadilisha Joto

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Faharasa ya Polarization (PI)

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Voltage ya Mtihani Iliyopendekezwa

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Mapendekezo ya Mwenendo

Upinzani Wa Insulation Wa Chini (IEEE 43)

Per IEEE Std 43, the minimum recommended 1-minute insulation resistance at 40 °C is:

R_min = kV + 1 (MΩ)

Where kV is the rated voltage in kilovolts. For a 4160V motor: R_min = 4.16 + 1 = 5.16 MΩ.

Kubadilisha Kwa Sababu Ya Joto

Insulation resistance approximately doubles for every 10 °C decrease in temperature. To normalize to 40 °C:

R₄₀ = R_T × C_T, where C_T = 0.5^((40 − T)/10)

For a reading at 25 °C: C_T = 0.5^((40−25)/10) = 0.5^1.5 = 0.354. So a 500 MΩ reading at 25 °C becomes 177 MΩ at 40 °C.

Faharasa ya Polarization (PI)

PI = IR₁₀min / IR₁min

PI Value	Hali Ya Insulation
< 1.0	Hatari — usienergize
1.0 – 2.0	Questionable
2.0 – 4.0	Nzuri
> 4.0	Excellent

Voltages Ya Mtihani Iliyopendekezwa (IEEE 43)

Upinzani Uliokadiria wa Motor	DC Voltage Ya Mtihani
< 1000 V	500 V DC
1000 – 2500 V	500 – 1000 V DC
2501 – 5000 V	1000 – 2500 V DC
5001 – 12000 V	2500 – 5000 V DC
> 12000 V	5000 – 10000 V DC

⚠️ Important: Mtihani wa IR mmoja unakuwa na maana chache kuliko mwenendo. Kila wakati linganisha na mitihani iliyotangulia iliyofanywa chini ya hali sawa. Kushuka ghafla (>50%) kunashangilia zaidi kuliko thamani kamili ya chini lakini thabiti.