Discourse on Mag monitoring

Date: 2025 06-June 18

Clayton 0:

do you know what a mag drive is?

ChatGPT0:

Yes—I do.

A mag drive (short for magnetic drive) typically refers to a type of sealless pump or coupling where power is transmitted from the motor to the pump using magnetic fields instead of a direct mechanical connection. The most common applications are magnetically driven pumps used to handle hazardous, corrosive, or high-purity liquids.

⚙️ How it works:

Clayton 1:

great. We have a mag drive that is meant to couple a a 1200 hp motor to a raw sewage pump.

To clarify, this mag drive is more than just a coupling. It is like a clutch, that helps control the power transmitted from the motor to the pump impeller. I will heck the make and model for clarity.

The pump shaft broke, which connects the mag drive to the pump impeller. The motor is mounted on top of the mag drive. The break in the shaft between the pump and the mag drive was not straight across the shaft, in the shortest possible distance with a circular cross section - instead the shaft broke with with roughly an oval cross section, at an angle. The broken shaft kept spinning, causing a cam-like action on the broken upper section against the now-stopped lower broken shaft section (attached to the pump impeller, which is supported from below). This cam-like motion caused compressive forces to be transmitted through the shaft to the mag body. So, we are worried about electrical damage to the mag drive.

If we try to turn it back on, the mag might fail. Maybe it will not turn back on. Maybe it will fail and vibrate. If it does turn back on, I am trying to imagine how it might fail. Is vibration monitoring a good heuristic? What are other forms of monitorig that could be used to assess the mag for peace of mind, if it does turn on?

Chat GPT 1:

Excellent description—very clear. You’re thinking about this exactly the right way, and you’re absolutely right to be concerned about both mechanical and electrical damage.

Let’s break this down with failure modes, diagnostics, and monitoring recommendations for your situation:

⚠ Failure Modes to Expect:

  1. Demagnetization of the Magnetic Assembly:

    • High compressive or impact loads can crack, chip, or partially demagnetize the permanent magnets.

    • If partially demagnetized, the drive may transmit torque poorly or slip entirely.

    • If fully demagnetized, no torque will transmit to the pump.

  2. Bearing or Bushing Damage:

    • Many mag drives use internal sleeve or thrust bearings (often ceramic or carbon) on the wetted side.

    • The cam-like action you described could have crushed or fractured these bearings.

    • If these fail, expect rubbing, heat generation, or full mechanical seizure.

  3. Rotor Imbalance / Magnet Misalignment:

    • The eccentric force from that broken shaft would have caused bending moments on the driven rotor.

    • Expect imbalance-induced vibration at startup or under load.

  4. Electrical Failure of Drive Motor (Induced Currents):

    • If metal-to-metal contact occurred within a magnetic field, eddy currents or shorted turns in motor windings may be a concern, but this is secondary compared to mechanical damage unless you saw sparks, smelled ozone, or tripped protections during the event.

🛠 Diagnostic & Monitoring Recommendations:

Method Why Recommendation
Vibration Monitoring (Critical) Detects imbalance, bearing failure Use accelerometers or portable vibration analyzers at startup and during operation. Baseline readings needed.
Slow Hand Rotation (If Safe to Do) Feel for roughness, seizing, or imbalance ONLY if decoupled or disconnected from power. Feels for drag, binding, or “clunkiness.”
Electrical Insulation Resistance (Megger Test) Detects motor winding damage or shorts Especially before energizing. Also test for grounding faults.
Torque/Slip Monitoring (If Possible) Measures torque loss or slippage Some mag drives have torque limiters or slip sensors. If not, you may infer by pump flow/pressure output.
Temperature Monitoring (Startup) Detects friction or bearing failure Use IR thermography or RTDs on bearing housings. Excess heat = probable failure.
Pump Suction/Discharge Pressure and Flow Tests Detects partial failure under load Compare to known good baseline performance for that pump.
Visual Inspection (Boroscope if Needed) Check visible cracks, magnet debris Especially if you can see into coupling casing, or if disassembly is feasible.

⚡ If the Mag Drive Is Damaged:

✅ Suggested Action Plan Before Restart:

  1. Decouple the motor from the pump (if possible).

  2. Conduct megger/IR tests on motor.

  3. Perform slow hand rotation of pump and mag drive to feel for abnormalities.

  4. Install temporary vibration monitoring (portable system or temporary mounted accelerometers).

  5. Start with no load or minimum load, and monitor:

    • Vibration

    • Temperature rise

    • Flow/pressure stability

  6. Prepare to trip manually at first sign of abnormality.

⚙️ Next-level (if budget allows):

Let me know when you get the make and model. I can give you failure specifics for that unit.

➡️ Summary:
Vibration is your first, best heuristic. Combine with temperature and torque/output monitoring. If you get abnormal vibration right away — stop immediately. Otherwise, cautiously proceed and build baselines for future trending.

Want help drafting a restart checklist or diagnostic plan? Just say the word.

Clayton 2:

(Question for Mike: Speed monitoring - how does this currently happen in our Ovation system or otherwise?)

I want a handheld vibration meter, and a handheld laser thermometer with a data link cable and a micro sd card.

Where would i expect head build up? Is this accessible and checkable from the outside during operation using a laser thermometer?

Would a handheld vibration unit be useful in the hands of a non-expert, or would only advanced and specialized users and equipment provide meaningful information?

Chat GPT 2:

Great thinking. Let's break this down clearly and directly:

✅ 1. Handheld Vibration Meter (For Non-Experts):

✔ Good News:

These devices are designed for non-experts to:

Verdict: YES — useful for non-experts with basic training. They won’t replace spectrum analysis, but they will absolutely catch gross problems like imbalance or bearing failure.

✅ 2. Laser Thermometer (IR Gun with Data Logging):

✅ 3. Where Would Heat Build Up?

Component Reason for Heat Checkable with IR gun?
Mag Drive Outer Housing Eddy currents, misaligned rotor, internal friction ✔ Yes, surface check.
Pump Bearing Housings Bearing damage, misalignment ✔ Yes, external surfaces.
Motor Bearings (DE/NDE) Misalignment, loading ✔ Yes. Check both ends.
Motor Body (Frame) General electrical load heating ✔ Yes. Baseline required.

⚠ Caution: IR guns cannot see inside; if friction or heat builds on the wetted side of the mag drive (internal bearings), surface heat may be delayed. Rising outer casing temps is still a strong indirect indicator of trouble.

✅ 4. Using These Tools in Combination:

✅ 5. Expert vs Non-Expert:

Tool Non-Expert Usefulness Advanced Analysis
Handheld Vibration Meter ✔ Detects imbalance, bearing issues, misalignment ❗ Advanced spectral analysis for diagnosing exact failure mode
IR Thermometer ✔ Detects hot spots on motor housings, bearings, pump casing ❗ Thermal imaging camera better for subtle thermal gradients

If this mag drive/motor assembly is critical equipment, periodic professional vibration analysis (e.g., FFT spectrum analysis) is recommended.

📦 Suggested Equipment Shopping List:

  1. Vibration Meter: Fluke 805 FC (data logging, Bluetooth, simple UI).

  2. IR Thermometer: Fluke 568 or Extech IR320 with data capability.

  3. Micro SD / USB connection for data export to logs or spreadsheets.

Let me know if you’d like specific product recommendations or procedures to draft a step-by-step checklist for startup diagnostics. Happy to help you build that.

Want that? Just say “diagnostic checklist please” and I’ll write one.

Clayton 3:

Yes, diagnostic checklist please. Also, first, please provide a paragraph and a haiku about what is vibration spectrum analysis.

ChatGPT 3:

Excellent choice. Here's your material:

📖 What is Vibration Spectrum Analysis? (Paragraph)

Vibration spectrum analysis is a diagnostic technique used to understand the health of rotating machinery by breaking down vibration signals into their individual frequency components. Using tools like accelerometers and spectrum analyzers, it transforms raw vibration data into a frequency-domain graph—called a spectrum. Peaks at specific frequencies correspond to particular mechanical issues: imbalance shows up at the running speed (1× RPM), misalignment at 2× or 3× RPM, and bearing defects at characteristic defect frequencies. Unlike simple vibration readings, spectrum analysis can pinpoint what is wrong, where, and how severe—making it one of the most powerful tools for predictive maintenance and failure prevention.

🍂 Vibration Spectrum Analysis (Haiku)

Whispers in the steel —
Hidden fractures, out of round,
Frequencies reveal.

✅ Now, your Diagnostic Checklist is next. Here it comes:

📝 Diagnostic Checklist for Restarting a Mag Drive Pump After Shaft Failure

⚙️ 1. Pre-Inspection (System Off, Locked Out)

⚙️ 2. Electrical Tests (Before Energizing)

⚙️ 3. Instrument Setup

⚙️ 4. Initial Startup (No Load / Jog Mode if Available)

⚙️ 5. Ramp-Up to Operating Speed

⚠️ Red Flags to Watch For:

Symptom Likely Cause Action
Abnormally high vibration at 1× RPM Imbalance/misalignment Stop. Inspect.
Vibration at multiples of 1× (2×, 3×) Shaft misalignment or looseness Stop. Inspect.
Vibration at high frequencies Bearing or internal mag drive damage Stop. Inspect.
Rapid temperature rise Internal bearing friction or magnetic drag Stop. Inspect.
Electrical overload/trips Rotor damage or mechanical drag Stop. Inspect.

⚙️ 6. Post-Test Review

Optional Next Step: Want a fillable PDF version of this checklist for field use? Just say the word.

Would you also like recommendations for baseline vibration levels or a template log sheet to go with this?