DC MOTORS REWINDING

Below are explanations on the operations performed on your engine that was brought to ÖZGÜR BOBİNAJ for winding as well as details on our process of quality, our undeniable proper pride.

1. Preliminary Expertise

a) The engine is subjected to visual examination. As assessment is made through the examination of structures and accessories such as Couplings, Shafts, Connectors on its trunk and the findings are recorded.

b) The location of the coupling or the pulley is measured by compass and brought under record. The coupling/pulley, if present, are drawn and disassembled. The pulley is disassembled by dismantling its screws in case it is of screw-tightened type. If any, the locking bolt is dismantled if the coupling/pulley hosts shrink fit.

The coupling/pulley are drawn by a 120-degree special drawing machine. Disassembly is performed by the application of heat via oxygen welding in order not to damage the materials in couplings/pulleys, which have close tolerances.

c) Relying on the information taken from the customer, a preunderstanding is reached about the causes of the problem, after which the normal and advanced expertise methods to be applied are identified.

d) The winding on the coupling location is measured via comparator after the coupling/pulley are disassembled. As a standard, the winding on the coupling location is performed through the middle of the shaft’s coupling location during which it is checked whether the winding is within the 3-5% limit value.

2. Disassembly

a) The bolts of the covers are dismantled, after the covers are marked with dots. If any, the covers are disassembled by the help of drawing bots or levers. In a manner not to drop them on the shaft, heavy covers are disassembled by crane or light ones are done so manually, after which they are placed over the universal palette.

b) Bearings and greasing flanges are disassembled by rollers. Heat by oxygen welding is applied for close tolerances. If any, stay bolts on the greasing flanges are loosened.

c) Coals are dismantled and if necessary, the coal housing is disassembled.

d) A pipe in appropriate dimensions is attached to the rotor shaft, and it is disassembled from the stator’s interior by the help of a double crane or by the creation of a balance weight with a single crane.

3. Expertise

a) The tolerances of the cover and bearings together with the tolerances of the couplings/pulleys are measured via internal and external radius micrometers and they are recorded on the mechanic expertise form.

b) The isolation of the sturdy windings are measured by a megger devices are recorded on the electric expertise form. If the isolation is low, then energy cables are dismantled from the connector joints and the cause of the isolation lowness is identified.

c) The calorimeters and heaters are measured by multimeter and their resistance checks are performed.

d) Nucleus damage is checked. When possible, heating tests are performed on the nucleus, on which winding will be performed.

4. Preparation for Winding

a) The existing windings are disassembled by the drawing or combustion method without damaging their nuclei.

b) If heating or damage is detected in the nucleus, its repair and isolation is performed by partially or wholly dismantling it prior to winding. The dismantled nuclei are compressed in the press following repair and they are later assembled by bringing them into their dimensions.

c) After all isolation materials in the nucleus are cleaned by combustion, the nucleus and the endocavity are purged of their burrs by sandpapering and the cavity outlets are rasped and their aculeate points are filed.

d) After the nucleus is cleaned by pressurized air and solvents following the cleaning operation, it is rendered ready for winding by being dyed with prime paint.

5. Winding

a) Cavity isolation is performed with minimum F class nomex pressband. Both two head sections of the pressband are cut in a manner to protrude approximately 1 cm out of the cavity.

b) Wire selection is important for the bobbins. For ensuring quality, we use “Theic Polyesterimide and above Polyamide-Imide” enameled grade2 class wires that are resistant against corrosion and temperatures at 210 °C. This wire is manufacture upon special order and if it is not found in the suppliers in Turkey as enameling wire, we bring it from abroad.

c) Winding is performed with circular wires and using the reels, tensioning, mould and winding machines that are used for preparing bobbins in multiple-spir ones.

d) Sheet wires are cut in appropriate lengths and the enamels at their terminals are cleaned by rubbing them out.

e) The cut wires are twisted in a special form machine.

f) In armatures with circular wires, the bobbin wires are descended to the cavities with the accompany of polyester guides for ensuring that their enamel does not scratch by contacting nucleus when the bobbins are thrown into the cavities.

As the cavity outlets are open in sheet wires, the pressband corners are prepared in a manner to protrude outside the cavity and the bobbins are descended inside the cavity directly with pressband without contacting the nucleus.

g) In circular wire windings, nomex pressband is placed between the two bobbin groups in the cavity. Its purpose is to isolate the intervals between the two phases in the same cavity and also to isolate the bobbins of the same phase that have high voltage differences. In sheet wire windings, reinforcement is provided by placing iron mica or glass lath in the cavity base or in the intervals between the bobbins in the same cavity or over the bobbin.

h) The bobbin terminals laid on the collector are isolated by silicon macaron.

i) The bobbins are closed and their resistance against electromagnetic impacts are increased by shaping H Class glass or F Class fiberboards in a manner to rigidly telescope the cavities.

j) The bobbin head are laid onto the support circles located on both side and on the surfaces of which are isolated.

k) The windings or while depending their structure, the entirety thereof, are bandaged with polyglass band in order to resist the centrifugal forces. Special benches and apparatus, which provide tensioning at an appropriate torque, are required for this operation.

l) During excitation winding, we generally use H Class “Theic Polyesterimide and above Polyamide-Imide” enameled grade2 class wires that are resistant against corrosion and temperatures at 210 °C. When sheet wire is present like in rare cases,  inding is performed after the obtainment of a wire at the same enamel quality. The matter requiring attention is to create a channel between the excitation winding and the commutating pole that will allow the passage of sufficient cooling air.

m) The excitation windings are isolated with F class nomex pressband and installed on the poles. The winding terminals are, in a manner that is suitable polarization, connected to each other using silver welding; and the F1-F2 cable terminals are migrated to the connector and the winding terminals are lugged.

n) During the winding of the commutating poles, we generally use H Class “Theic Polyesterimide and above Polyamide-Imide” enameled grade2 class sheet wires that are resistant against corrosion and temperatures at 210 °C. Sometimes circular  ires are also used.

o) The commutating pole windings are isolated with F class nomex pressband and installed on the poles. The winding terminals are, in a manner that is suitable polarization, connected to each other using silver welding; soft multi-wired copper cables in appropriate dimensions that are coated with PVC are passed through them; silicon macaron is passed crossed over them; and the winding terminals are migrated to the connector, they are connected to brush holders and lugged.

p) During the winding of the commutating poles, we generally use H Class “Theic Polyesterimide and above Polyamide-Imide” enameled grade2 class sheet wires that are resistant against corrosion and temperatures at 210 °C. Sometimes circular wires are also used.

r) The commutating pole windings are isolated with F class nomex pressband and installed on the poles. The winding terminals are, in a manner that is suitable polarization, connected to each other using silver welding; soft multi-wired copper cables in appropriate dimensions that are coated with PVC are passed through them; silicon macaron is passed crossed over them; and the winding terminals are migrated to the connector, they are connected to brush holders and lugged.

s) Collector winding connections are made. Depending on the particularity, joining operation is performed by silver soldering or tig welding.

t) The windings are kiln-dried by being heated up to 130 °C for a period of 15 hours.

u) The windings are removed from the kiln and when they are still hot, they are varnished with kiln-dried-varnish that is applied via immersion and spraying method. This method allows the spreading of the varnish until the winding’s interior.

v) The varnished winding is again kiln-dried by being heated up to 130 °C for a period of 15 hours.

y) After the varnish has dried-up, its residues are cleaned from the nucleus.

z) Heat detector RTD is mounted on the heads of the excitation and commutating pole windings; their cables are migrated to the connector by using silicon macaron, and the cable terminals are lugged.

6. Winding Tests

a) Isolation tests are performed for the windings using megger.

b) The DC resistance of the windings are measured up to maximum 15 amperes and on 1/10000 sensitivity level.

c) Hi-POT and SURGE tests together with high voltage and isolation resistance tests against the chassis and the bobbin-spirs interval are performed for the windings.

d) Resistance checks are performed for the windings, the RTD calorimeters and the heaters.

e) Thepolarizations of the excitation windings are tested by magnetic sensors.

f) The winding-collector connections are measured and checked by our private production measurement device, rise

7. Cleaning, Maintenance and Repair Operations for the Windings and Parts

a)

b)

c) Lathing is performed on rings (if any) their ovality is thus brought around 2% and by grinding the surface, the unevenness values of the surface is brought within the interval of 1,25-1,75 micrometers.


d) The jag sockets of bolts, which have been corroded and which have filled with varnish, are cleaned by guide.

e) Malfunctioning housing locations and flanges are repaired by the bushing method and using a micrometer, it is checked whether it is in the specified tolerance.

f) The balance of the rotor and all its rotating parts is measured by half-wedge or full-wedge according to the ISO 1940-1 standard, the wedging manner of the coupling/pulley, and the manner of balancing. The balances of the coupling/pulley are measured separately by considering the same standard and wedging method.

8. Assemblage

a) A pipe in appropriate dimensions is attached to the rotor shaft, and it is assembled inside the stator by the help of a double crane or by the creation of a balance weight with single crane.

b) Internal grease covers are telescoped inside the shaft.

c) Bearings are heated by adding 80°C to the ambient temperature using an induction and demagnetization bearing device and following heating, they are demagnetized and installed on their housing over the shaft.

d) The oil sump inside the bearing and the grease covers are greased with sufficient amount of grease oil.

e) The covers are installed, looseness-protective washer is attached to all bolts and these are tightened with appropriate torque.

f) The brushes are installed after adjusting the distance between the brush holders and the ring between 2-2,5 mm.

g) Without scorching, the coupling/pulley is installed over the shaft by using a specially manufactured induction and demagnetization coupling heating device.

9. Final Test

a) Isolation tests of the windings are performed using megger.

b) The DC resistance of the excitation winding is measured.

c) The pole and the connection correctness is measured by the ancillary pole device.

d) The adjustment of the coal housing to the neutral region is performed by the neutral adjustment device.

e) The current and voltages are recorded by rotating the engine in its nominal voltage. The collector surface is cleaned by the coal lapping grinding wheels.

f) The engine is, by making connection with the cardan shaft, loaded on the generator that creates anticathexis by the 4 region and 2 region driver system. Arcing that may occur in the engine during this case is checked.

g) Vibration analysis and balance check are performed and the bearing performances are measured by making a vibration measurement on the housings when the engine is in its nominal revolution.

h) The sounds of the bearing flap and the bearings are listened.

i) The housing temperatures are measured and checked after 30 minutes of operation.

10. Packaging

a) The engine trunk that has passed the test is cleaned and dyed.

b) The engine, the dye of which has dried, is covered by stretch film, bound on the universal palette by a special tie and rendered ready for shipment.