Video summary

How to use Digital Inclinometer for measurement of leaning reverse deflection of OHE mast in Railway

Main summary

Key takeaways

Educational

Main ideas / lessons conveyed

  • The video shows how to use a digital inclinometer (Bass Professional GI 60) to measure the lean (inclination) of a railway OHE mast, focusing on the reverse deflection (how much the mast is leaning/deflecting in the reverse direction).
  • The inclinometer must be calibrated for vertical surfaces before use.
  • It demonstrates a calibration/verification method using a plumb bob, including use of a correction factor.
  • It explains how to convert inclinometer readings into the engineering unit mm per meter.
  • It concludes with a practical application: selecting the correct reverse deflection to set during mass grouting for the first erection, based on a desired deflection at the top.

Methodology / instructions (detailed)

A) Calibrate the digital inclinometer for a vertical surface

  1. Calibrate the horizontal spirit level first

    • Ensure the spirit level for the horizontal surface is located at the top.

  2. Prepare the inclinometer

    • Face the display toward yourself.
    • Place the device on a surface that is almost 90 degrees.

  3. Initial calibration hold

    • Hold for 10 seconds.

  4. Start calibration

    • Press the Calibrate (Cal) button.
    • Hold the Cal button for 1–2 seconds.

  5. First verification step

    • When the display prompts a calibration stage (subtitles show repeated “Cal to / Call one / Call two” style messages):
    • Rotate the device vertically by 180° and fix it again.

  6. Second calibration hold

    • Hold for 10 seconds, then press Cal again.
    • (If needed, re-press Cal when prompted—subtitles indicate a timing requirement.)

  7. Next stage

    • When the device indicates the next calibration stage:
      • “Zoom in mentally on the display” (as instructed by subtitles).
    • Hold 10 seconds, then press Cal when instructed.

  8. Repeat 180° rotation

    • Rotate vertically by 180°, hold 10 seconds, then press Cal again.

  9. Finish

    • When calibration completes, subtitles suggest completion around ~89° / 95° (caption inaccuracies likely).
    • After these steps, the device is considered calibrated for vertical-surface lean measurement.

B) Determine a correction factor using a plumb bob (verification)

  1. Use a plumb bob to measure “lean” near 90°.
  2. Determine a correction factor based on the plumb bob readings.
    • Subtitles suggest an observed correction factor around 11 cm (likely representing deviation at a reference condition).
  3. Apply the correction logic:
    • For zero leaning, subtract the correction factor from the inclinometer/plumb-bob-derived reading to obtain the actual leaning.

C) Measure leaning of the mast and express it as mm per meter

  1. Measure along the mast with a baseline

    • Mark two points on the mast:
      • Point A and Point B, separated by 1 meter.
    • Use the inclinometer along the mast and compare against this 1 m reference.

  2. Ensure output is in mm per meter

    • The inclinometer display should be set/converted to mm per meter (using the device’s mode/option buttons after calibration).

  3. Example reading and correction

    • Example described:
      • Reading at 1 meter: about 38 cm (caption/unit errors likely in subtitles).
    • After subtracting the correction factor (11 cm):
      • Remaining is about 2.7 cm.
      • This corresponds to approximately 27 mm per meter.
    • Reported inclinometer results fluctuate slightly, but average/approximate around 27–28 mm per meter.

D) Compare inclinometer vs plumb bob (practical pros/cons)

  • Agreement

    • Both methods produce close results: ~27 mm per meter.
    • Differences are small (subtitles mention ~1 mm at a time) and do not substantially affect overall calculations.

  • Inclinometer advantages

    • More reliable due to reduced human/manual error.
    • Easier for one-person operation (portable and lightweight).
    • Fast: press a button for lean reading after calibration.

  • Plumb bob disadvantages

    • Wind affects readings, causing the bob to drift.
    • Typically requires more people (subtitles suggest 2–3).
    • More time-consuming due to repositioning and repeated measurements.

E) Practical use: setting reverse deflection for mass grouting (first erection)

  1. Identify total mast height

    • Subtitles state total height as 95 m.

  2. Choose target reverse deflection at the top

    • Example: 30 mm reverse deflection at the top.

  3. Compute deflection rate (mm per meter)

    • Rule of thumb used:
      • 30 mm / 95 m = deflection (mm per meter)
    • Example calculation:
      • 30 mm / 95 m ≈ 3.15 mm per meter

  4. Interpret the result

    • Over the full 95 m, this corresponds to 30 mm at the top.

  5. Use a measure table / reference during grouting

    • Apply the computed mm per meter value at appropriate heights during grounding/mass grouting.

  6. Outcome

    • The method enables accurate placement of reverse deflection during grouting.

Speakers / sources featured

  • Bass Professional GI 60 digital inclinometer (device/model referenced)
  • Plumb bob (measurement tool referenced)
  • “OHE mast” / Railway overhead electrification mast (structure referenced; no individual named)

Original video