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API St 547:2005 pdf download

API St 547:2005 pdf download.General-purpose Form-wound Squirrel Cage lnduction Motors-250 Horsepower and Larger. When specified antifriction bearings may be supplied. The following conditions shall be met:
a. The dN factor is less than 300,0(M).
h. Antifriction bearings meet an ABMA Ll0 rating life of 100.0(M) hours in direct coupled applications with continuous operation at rifled conditions.
e. Ball and roller bearing manufacturing tolerance limits shall be in accordance with Table 4 of ABMA 20-19%. Hall bearings shall have ABMA C/3 or J4 clearances. Bearing Housings Bearing housings and shaft seals shall he designed to meet the requirements of LPS5 per NEMA MG I as a minimum, A permanent indication of the proper oil level to within 0.04(1 in. (I mm) of the actual operating oil level shall be clearly marked on the outside of the bearing housing with metal lags. marks inscribed in the castings, or other durable means. If the oil-level indicator breaks, the resulting drop in oil level shall not result in Loss of bearing lubrication, that is, reduction of the oil level below the level required for oil-ring operation. The housings shall be equipped with constant- level sight-iced oilers at least 8 oz. (0.25 L) in size, with a positive level posilioner (not a set screw), glass containers. pmtective wire cages, and supplemental support in addition to the piping. Housings for ring-oil-lubricated bearings shall he provided with plugged ports positioned to allow visual inspection of the oil rings while the equipment is running. Bearing housings shall be located by cylindrical precision dowels or rabbitted fits. Shaft Seals Shaft seals for hydrodynarnic radial hearings shall conform to the following:
a. Primary bearing housing/enclosure seals shall be made from a non-sparking material.
b. For WP II motor enclosures, primary seals shall be split labyrinth type end seals on both sides of each bearing enclosure,
c. TEFC motors whose enclosure mates with and completes the inboard section of the bearing housing shall have a split labyrinth type end seal on the outboard end of the bearing housings where the shaft passes through the bearing enclosure.
d. The seals shall not contact the shaft sshile under normal operation and shall have a minimum life expectancy of 5 years under usual service conditions. Lip type seals shall not be used.
e. Oil shall not leak past the seals during both stationary and normal, rated operating conditions. Shaft seals for antifriction hearings shall conform to the tollowing:
a. For grease lubricated bearings, replaceable labyrinth shaft seals shall be used and shall he the non-contact or non-contacting-while-rotating type with a minimum expected seal life of five years under usual service conditions.
b. Oil or oil-mist lubricated bearings shall have seals a.s above, or lip type seals on both outboard and inboard sides of the bearing to reduce oil migration into the environment and motor interior.
c. Cast iron inner bearing caps shall be provided to minimize grease or oil migration to the motor interior. Bearing Insulation l3eanngs shaH be electrically insulated. A shorting device shall be provided in the bearing housing on the drive end, For double-end drivers, the coupling on one end also shall be electrically insulated and the bearing housing shorting device provided on the opposite end. The hearing insulation shall he permanent and non-deteriorating during assembly and disassembly of the hearing. This shall have been verified by a type test where a hearing having an identical insulation system is assembled and disassembled a minimum of 10 tunes; followed by a measurement of its insulation resistance. The bearing insulation resistance shall be a minimum of 10 megohms at a test voltage of 50 V DC minimum.
2.4.8 Lubrication
Ilydrodynamic bearings shall use mineral oil and shall he arranged for ring-type lubrication in accordance with the bearing manufacturer’s recommendations.
2.4.9 End Play and Couplings 1-fydrodynamnic radial bearing motors shall have a total end play of at least 1/2 in. 13 mm). The design of the motor shall ensure that the magnetic center shall be within 20% of the total end float from the center of the end float limit indicators (e.g., /32 in. for a 1/2 in. total end float) or 2.6 mm for a 13 mm total end float. Flexible couplings used with hydmdynamic radial bearing motors shall be of the limited.end4loat.type. The total end float shall be limited to /l6 in. (5 mm).


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