What is shaft relative vibration?

Shaft relative vibration is the dynamic displacement of a rotating shaft measured relative to its bearing housing, typically using non-contact proximity (eddy current) probes. It is expressed in micrometers peak-to-peak (μm p-p) and captures shaft motion that bearing-mounted sensors may miss.

What is the difference between proximity probes and accelerometers?

Proximity probes (eddy current sensors) measure shaft displacement relative to the bearing housing without contact. Accelerometers measure absolute bearing housing vibration. Proximity probes are essential for fluid-film bearing machines where shaft motion may not transmit fully to the housing.

What is the difference between ISO 7919 and ISO 20816?

ISO 7919 covers shaft relative vibration measured by proximity probes. ISO 20816 (which replaced ISO 10816) covers bearing housing vibration measured by accelerometers or velocity sensors. Both use zone classification A/B/C/D but measure different quantities.

What is a shaft orbit?

A shaft orbit is the two-dimensional path traced by the shaft centerline during rotation, constructed from two orthogonal proximity probes (typically X-Y). Orbit shape helps diagnose faults: circular orbits suggest unbalance, figure-8 patterns suggest misalignment, and banana shapes suggest rub.

What is acceptable shaft displacement?

Acceptable displacement depends on machine type and speed per ISO 7919. For general machinery at 3000 RPM, Zone A (newly commissioned) is typically ≤50 μm p-p, Zone B (acceptable for long-term operation) is ≤100 μm p-p. Higher speeds generally require tighter limits.

Bepul Muhandislik Vosita #027

Val Nisbiy Tebranishi Chegaralari

ISO 7919 seriyasi bo'yicha yaqinlik zondlari (proximity probes) bilan o'lchan val nisbiy tebranishini baholang. Turbinalar, generatorlar va aylanuvchi mashinalar uchun tebranish zonasini (A/B/C/D) aniqlang.

ISO 7919 Yaqinlik Zondlari Zone A–D

Results

Tebranish Zonasi (ISO 7919)

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O'lchan Siljish

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A/B Zona Chegarasi

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B/C Zona Chegarasi

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C/D Zona Chegarasi

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Val Orbita Izohati: Ushbu kalkulyator yagona o'qlama (S ning) tepasidan pastligiga chiziqli siljish amplitudasini hisoblaydi._maks) amplitudani pik-to-pik shjishishiga. To'liq val orbitasini analiz qilish uchun ikkita ortogonal yaqinlik sensori (X-Y) talab qilinadi. Orbital shaklida qo'shimcha diagnostik ma'lumot bor — aylana orbitalar disbalanss bo'yicha, raqam-8 shaklining shtamplari hizalanishdagi xatolikni ko'rsatadi.

ISO 7919 — Val nisbiy vibratsiya

ISO 7919 teging bo'lmagan yaqinlik sensorlari (orti-elektron sensorlari) bilan o'lchangan val nisbiy vibratsiyasi uchun baholash mezonlarini belgilaydi. Vibratsiya mikrometr (µm p-p) da pik-to-pik val siljishida ifodalashtiririladi.

Tezlikka bog'liq zona chegaralari

Zona chegaralari val aylanish tezligiga bog'liq. Umumiy munosabat quyidagidek:

Where n val tezligi RPM da va A har bir zona chegarasi va mashinaning turi uchun farq qiladigan koeffitsientdir.

Zona tasnifi

Zone	Tavsif	Action
A	Yangi ishga tushirilgan mashinalar	Normal — harakatga kelishning zaruriyati yo'q
B	Uzoq muddatli ishlatish uchun qabul qilinadigan	Kuzatish — normal operatsiya
C	Uzoq muddatli qabul qilinmaydi	Texnik xizmatni rejalashtiring — sababni tekshiring
D	Zarar bo'lishi mumkin	Darhol amalga oshirish — agar kerak bo'lsa, to'xtatib qo'ying

Soddalashtirilgan zona chegaralari mashinaning turga ko'ra

Machine Type	A/B (μm p-p)	B/C (μm p-p)	C/D (μm p-p)	Typical Speed
Umumiy (≥10 MW)	50	100	170	1000–3000 RPM
Bug' turbinasi/generator	50	100	170	1500–3600 RPM
Gas turbine	50	100	170	3000–15000 RPM
Suv turbinasi/generator	80	160	260	75–750 RPM
Reciprocating	80	160	260	200–1000 RPM

Amaliy Misol

Misol — 3000 RPM da bug' turbinasi

Given: Steam turbine, speed = 3000 RPM, measured shaft displacement = 75 μm p-p

Zone boundaries: A/B = 50 μm, B/C = 100 μm, C/D = 170 μm

75 μm > 50 μm (A/B) and ≤ 100 μm (B/C)

Result: Zone B — Acceptable for long-term operation

⚠️ Note: This calculator uses simplified zone boundaries from ISO 7919-1 (general guidelines). The actual ISO 7919 series (parts 2–5) provides speed-dependent curves for specific machine types. Always consult the relevant part of ISO 7919 for contractual or warranty evaluations.