PLAMITZER PDF DOWNLOAD FREE

The experiments carried out at ITWL demonstrated that penetration of oil e. Some other effects associated with variation in the nature of pulsation are discussed as well when defects such as shorts or breaks occur in the generator armature or stator. If the pulsation with re- 7 Delay in operation of carbon controllers ranges from 30 to 50 ms, electronic ones from 3 to 20 ms. Breaks in the armature windings result in drops of the groove pulsation from 0. Remember me on this computer.

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The examinations were carried out under laboratory conditions in a test bench for driving units with external excitation from a DC power supply module. Frequency fk of these pulsations depends on 1 In the avionic technology there is a term of so called buffer power, i. It results from the need to keep the same composition of ingredients for produc- tion of brushes.

The first rule for the maintenance personnel of an aircraft entrusted to replace brushes is to select brushes with the same serial number, i.

Phase angles for individual half-sine curves of commutator-type pulsations Fig.

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In the future it will be also pos- sible to design an automatic, electronic tester. The highest Lc parameter exhibits the coil that is the latest commutated one within the groove with the worst conditions for commutation. The frequent reason for scratching is polishing the commutator surface with too 2 Designers struggle to fabricate DC generators in such a way that the currently commu- tated turn is in a magnetically neutral area when two sectors of the commutator are be- ing made together with a winding coil attached to that sector via the brush.

Actually, it would be a tester capa- ble of investigating technical condition of commutator-type DC generators as mentioned in Section 2 groove pulsations across the armature supplemented with a testing path for detection of shorts between windings. Initially, it is enough to assume that the sampling frequency of the recorder should be tenfold higher than the frequency of groove pulsations for a specific commutator-type DC generator.

The material composition4 of carbon brushes should also be accord- ingly selected: On the other hand, the experience of the authors demonstrates that it is possible to measure amplitudes of groove pulsations and detect breaks in the armature windings by means of a recorder with the sufficient sampling frequency.

Under such circumstances, even when to consider the additional effect of the voltage controller7, detection of the winding break by measurements of the output voltage Uw during operation of the DC generator proves infeasible. Therefore, the number of commutator sectors that are bridged at a time is also increased. If amount of oil that penetrated into the commutator unit is considerable, one has to be aware that all the brushes may have to be replaced.

Therefore, a DC generator can serve as a good converter that enables diagnosis of own antifriction bearings.

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That phenomenon, according to the litera- ture sources, is caused by the following factors: Skip to main content. The referred studies and own investigations demonstrate that monitor- ing and measurements of pulsation components together with monitoring and measurements of some easy available parameters of the commutator and brush subassembly enable early detection of defects within that subassembly as well as undertaking appropriated preventive measures to avoid more serious failures.

K — number of commutator sectors. Variations in number and geometrical shape of simultaneously bridged commuta- tor sectors due to abrasive wear and reduction in height of that sectors: Evaluation of commutation processes in electric machines under heavy-duty conditions, Electrotechnical Review,No.

However, they can be useful as a source of diagnostic information about other defects and deficiencies, e.

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To prevent sparking under brushes caused by mechanical reasons, the commutator surface must be extremely smooth and brushes must be run-in3.

The examination method is colloquially referred to as FDM-A plqmitzer is based on meas- urement of modulations of voltage frequency measured for the voltage compo- nent that represent the groove pulsation.

One has only plamizer count up the number of grooves for a specific DC generator. Consequently, it may result in growth of pulsation am- plitude and pdg deterioration of the commutator subassembly. In addition, after having the voltage controller connected, the amplitude of these pulsations increases and other unfavorable effects occur as well, including pulses of voltage surges.

Ends of these coils are attached to commutator sections. It is also possible to develop a semiautomatic diagnostic tester that should al- low the operator to key in the number of armature grooves or the operation mode of the DC generator with the already preloaded table of design parameters for all plamitezr DC generators being in use within the country and to track am- plitudes of waveforms for individual grooves of the armature — it would be neces- sary to track the peak values for each groove pulsation.

Particular attention is paid to effects associated with the commutation process, with con- sideration of symptoms related to failures, possibilities of their detection and prevention.

The waveforms displayed on the oscilloscope tube can be then recorded. Therefore, according to [2], commutator-type pulsations cannot plaitzer used to infer about the size of defects in kinematic pairs of the driving unit that actuates the DC generator since plamtizer is no linear relationship between the phase modulation of the frequency for that com- ponent of pulsations and oscillations of the angular frequency due to defects in individual kinematic pairs.

To measure the associated phenomena one can use a thin contact brush glued to the conventional copper and graphite brush and separate from the latter with some insulating material. Breaks in the armature windings result in drops of the groove pulsation from 0. Commutator-type pulsations according to own investigations of the authors The investigations that have already been completed by the authors [2, 4] re- vealed that amplitudes of these pulsations are directly proportional to the load from the output current current load.