Code of practice for overhauling of dc motors with anti-friction/sliding ...

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IPSS:1-03-033-03 3.2 In case of sliding bearing type motor, visual inspection and proper marking of all external parts in addition to clause 3.1.1 including oil pipe line connections and thermometer installation should be done. Also take bearing clearance wherever possible. The pre movement of oil ring may be checked before dismantling. 3.3 Check the IR value of the armature, IP and compensating winding and field circuit and record the readings. Wherever insulated bearing are there, they should be meggered and values recorded. 3.4 Make a physical inspection in respect of the following and prepare a defect list prior to dismantling. 3.4.1 Take the beating of coupling shaft. 3.4.2 Check the condition of brushes w.r.t. its remaining wearing depth, condition of pigtails, carbon brush holders, brush boxes, tension adjustors, etc. 3.4.3 Note the condition of the shaft, fan, fan cover, foundation legs, terminal board and terminals. 3.4.4 Check the air gap between main pole and armature. 3.4.5 Make a physical and schematic diagram of connection of armature, interpole, compensating winding, main pole coils. Make a sketch of terminal board connections and their markings. 3.5 On the basis of above pre dismantling inspection/ checking, prepare a consolidated defect list to take up necessary rectification during overhauling. 4. DISMANTLING 4.1 General 4.1.1 Remove ventilation system i.e. blower, ventilation duct, if any. Disconnect the connections at the terminal board, brush holder arms, rocker assembly, etc after marking suitable identifying marks on the parts which are connected electrically i.e. bus bars/cables and are to be disconnected. 4.1.2 Proper identifying marks are put on all the parts to be dismantled so that the respective parts could be assembled as per the original assembly after repair. Page 2 of 9
IPSS:1-03-033-03 4.1.3 The dismantling is to be carried out as per the following procedure : - Take out the coupling with the help of a hydraulic puller. In some cases heating may be required. Care is to be taken not to overheat. Inspect the shaft surface, bore of coupling, key/keyway for any marks of wear & deformation. - Open top / bottom half fixing bolts along with bearing cartridge bolts to falcilitate removal of top half of the motor field body. (This is required for split frame dc motors). The armature then is lifted up from the bottom half and placed on work bench. - In the case of a non-split construction, the armature is required to be threaded out after dismantling the end shields on both sides. 4.2 Dismantling of motor with anti-friction bearings. 4.2.1 Remove ventilation system i.e. blower, ventilation duct, if any. Disconnect the connections at the terminal board, brush holder arms, rocker assembly, etc after marking suitable identifying marks on the parts which are connected electrically i.e. bus bars/cables and are to be disconnected. 4.2.2 In case of non-split construction, the armature is to be threaded out. Follow the instructions for dismantling of the motor as supplied by the machine manufacturer”. 4.2.3 Wherever field system is in two halves, mark properly the interpole connections, current collecting half bus bars and rocker assembly position before taking them out. 4.2.4 Open the bearing and take out the top covers. Put proper identification. Take out top half of the bearing (if the bearing is in two halves, after marking properly). Take out labyrinths from both ends of the bearings. 4.2.5 In case of large motors, sufficient room is normally not available for threading out of the armature from the field body (non-split type) at the drive location. In this case, both armature and the stator body is to be taken out from its position and shifted to a place where EOT crane is available. 4.2.5.1 Threading out of the armature is to be done after removing the motor/generator to a place where the stools have been prepared before hand. Depending upon the situation, either the field body or the armature can be threaded out. Use of balance beam which facilitates easy thread out should be preferred. Soft gasket may be inserted in the air gap to avoid damage to core/winding. 4.2.6 In case of non-split construction, the armature is to be threaded out. Soft gasket may be inserted in the air gap to avoid damage to coir/winding. Page 3 of 9
Page 1: IPSS 0. FOREWORD INTER PLANT STANDA
Page 5 and 6: IPSS:1-03-033-03 seating should be
Page 7 and 8: 5.4.2 Other Components IPSS:1-03-03
Page 9: IPSS:1-03-033-03 TABLE - 1 PERMISSI

Code of practice for overhauling of dc motors with anti-friction/sliding ...

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