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Te sting and Co mmissio ning Pro ce d ure Fo r Mo to rs // Pho to b y TECO Mid d le East (TME)

Edvard

Testing and Commissioning Procedure For Motors

Scope Of Motor Testing

It should be noted that the scope of motor testing depends upon the motor type and size, this beingindicated on the inspection f orms.

Motor vibration shall be measured in a tri-axial direction, i.e.:

Point x axis – side of bearing housing at shaf t height

Point y axis – top of bearing housing

Point z axis – axial of bearing housing at shaf t height

The measurements shall be carried out with an instrument conf orming to ISO 2954 (10-1000 Hz frequencyrange). With the motor at normal operating temperature, the vibration velocity shall not exceed 2.8 mm/sRMS, or 4 mm/s PEAK, in any direction.

For bearings f itted with proximity probes, the unf iltered peak-to-peak value of vibration (including shaft‘run-out‘) at any load between no load and f ull load, shall not exceed the f ollowing values:

50 µm f or two-pole motors

Mo to r b e aring (p ho to b y CCLW INTERNATIONAL)

The p ro fi le o f the fo o t co ntact are a (Fig ure s 1, 2 and 3)

60 µm f or f our-pole motors

75 µm f or six-pole or higher motors

Bearing temperature rise limits followinga ‘heat run’ of 3.5 – 4 hours are asfollows:

Rolling bearings:

Outer ring measurement max. 90 °C

Temperature rise f rom ambient max. 50°C

Sleeve bearings:

Oil temperature max. 90 °C

Bearing temperature rise by RTD max.50 °C

Lub. oil temperature rise f rom ambientmax. 30 °C (for forced lub. oil systems).

When commissioning or re-commissioningmotors, precautions shall be taken toavoid excessive vibration caused by the phenomenon known as ‘soft foot‘; i.e. f eet which do nothave solid f lat contact with the base prior to the tightening of the holding-down bolts.

This may be measured and rectif ied during installation or detected during running by the loosening of eachholding-down bolt in turn while measuring motor vibration.

Motor ‘Soft Foot’ Condit ion

‘Sof t f eet’ are those which do not have solid f lat contact with the base prior to the tightening of theholding-down bolts; one or more f eet may be ‘sof t’ as shown in Figures 1 to 3.

The prof ile of the f oot contact area may be as shown in Figures 4 to 6.

Figure 1 - Machineresting on 3f eet, f oot 4 israised or‘sof t’

Figure 2 - Machine resting on diagonal f ormed by f eet 3 and 4, f eet 1 and 4 are ‘sof t’

Figure 3 - Bottoms of all 4 f eet are not parallel with base, f eet 3 and 4 are ‘sof t’

Pro fi le o f 'so ft fo o t' co ntact are a

NOTE: Re-machining ofrotor f eet isrequired inFigures 4 and 5;temporary useof wedge-shaped shimsmay beacceptable (maintenance).

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Forms

Form 14 – Inspection of electric motor – Cage-induction type (incl. control unit )

Insp e ctio n o f e le ctric mo to r cag e -ind uctio n typ e (inc lud ing co ntro l unit)

Form 4 – Inspection of Switching Units – HV Switchgear

Insp e ctio n o f Switching Units - HV Switchg e ar

Form 11 – Inspection Of Outgoing Unit – LV Switchboard

Insp e ctio n Of Outg o ing Unit - LV Switchb o ard

Reference: Field Commissioning and Maintenance Of Electrical Installations and Equipment Manual

Edvard - Electrical engineer, programmer and f ounder of EEP. Highly specialized f or designof LV high power busbar trunking (<6300A) in power substations, buildings and industryf ascilit ies. Designing of LV/MV switchgears. Prof essional in AutoCAD programming and web-design. Developer of awsome electrical design sof tware ePlusMenuCAD. Present onGoogle+.

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