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Calibration of The Yoke

I. This document outlines the calibration procedure for AC/DC yoke equipment, requiring them to lift a minimum weight based on their pole spacing and current type. II. The procedure involves testing the yoke's ability to lift a 4.5kg or 10lb weight for AC yokes and an 18kg or 40lb weight for DC yokes at their maximum pole spacing. III. Yokes failing to lift the minimum weight must be repaired and retested, and calibrations must occur daily when in use and after repairs, with a maximum idle period of 6 months between calibrations.

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Hussain Shariff
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2K views2 pages

Calibration of The Yoke

I. This document outlines the calibration procedure for AC/DC yoke equipment, requiring them to lift a minimum weight based on their pole spacing and current type. II. The procedure involves testing the yoke's ability to lift a 4.5kg or 10lb weight for AC yokes and an 18kg or 40lb weight for DC yokes at their maximum pole spacing. III. Yokes failing to lift the minimum weight must be repaired and retested, and calibrations must occur daily when in use and after repairs, with a maximum idle period of 6 months between calibrations.

Uploaded by

Hussain Shariff
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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AC/DC Yoke Equipment Calibration Procedure

Scope

This document states step by step procedure for Calibrating & checking of lifting power of
Portable AC/DC Yoke equipment.

Reference documents

ASME Section V Article 7 – 2019 edition


SE709 Article 25 – 2019 edition

Apparatus required

*Lifting Test Blocks


 A dead weight block made of steel plate or rectangular bar with having a mass of
minimum 4.5 kg or 10 lb & 18 kg or 40 lb.
 The major dimension of the plate or bar shall be greater than the max pole spacing of
the yoke magnet.
 Each weight shall be weighed with a scale from a reputable manufacturer and stenciled
with the applicable nominal weight prior to first use.
 A weight need only be verified again if damaged in a manner that could have caused
potential loss of material.

Calibration Procedure

I. Each alternating current electromagnetic yoke shall have a lifting power of at least 10 lb
(4.5 kg) at the maximum pole spacing.

II. Each direct current or permanent magnetic yoke shall have a lifting power of at least 40 lb
(18 kg) at the maximum pole spacing.

III. Under the conditions where yoke leg contact is similar to what will be used during the
examination or refer table 1 for relation between leg spacing & mass

IV. To lift the steel with a mass of 4.5 kg requires a lifting force of 45 N.

V. When electromagnetic yoke failing to lift a minimum mentioned weight then it should be
repaired or recoiled & retested again using same procedure.

VI. Frequency of the calibration shall be prior to use each day the yoke is used. The
magnetizing power of yokes shall be verified whenever the yoke has been damaged or
repaired.

VII. Maximum calibration period during idle or without any duty cycle of the equipment shall
be 6 months.
Minimum Yoke Lifting Force
Yoke pole Leg Spacing
Type of Current
2 to 4 in (50 to 100mm) 4 to 6 in (100 to 150 mm)
AC 10 lb (45 N/4.5 kg) 10 lb (45 N/4.5 kg)
DC 30 lb (135 N/13.5 kg) 50 lb (225 N ∕23.0 kg)
Table 1

Figure-1

Reporting
The requesting document should fully define the extent of the written report required. A
comprehensive written report shall include all relevant information in sufficient detail so that the
tests could be duplicated later if desired.
The following data is recommended for a report requiring complete documentation of the tests:
*Recommended
Recommended pole spacing (max & min)
*Cross
Cross sectional dimension of the poles
*Electrical
Electrical supply (voltage, current & frequency)
*Current
Current wave forms available
*Dutyy cycle at maximum output in percentage
*Maximum current ON time
*Overall
Overall dimension of the equipment

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