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Zeszyty Problemowe – Maszyny Elektryczne Nr 68/2004

Witold Rams, Jan Rusek

AGH Kraków

PRAKTYCZNA DIAGNOSTYKA MASZYN INDUKCYJNYCH KLATKOWYCH

PRACTICAL DIAGNOSTICS OF SQUIRREL CAGE INDUCTION MACHINES

Abstract: The paper present diagnostic reports produced by diagnosing some machines in the industry. The machines

investigated drive coal mills, air blasters, water-feed pumps and smoke exhausters. Diagnoses of the state of their cages are

accounted for by scheduling reparations of these machines. Assessment of cage states was based on measurements of the

magnitude of the (1±2s)f

current components, where: s – slip, f

– frequency of the supply system. The measurements of

these components were performed during stationary operations by current loads. Additionally, the (1-2s)f

component was

measured during starting up as well. The measurements relied on non-invasive, digital registration of the secondary currents

in the on-site current transformers. All the on-site circuits were left intact, as only the Dietz mini clamps surrounded the leads

with secondary currents. The currents were registered in two phases, though only one signal was used for diagnostics. Two of

the machines were found to show up cage asymmetry characteristic for at least one broken bar. Discrepancy between the

magnitude of the (1-2s)f

component during starting up and steady state allowed to conclude that in the case of a double-cage

machine the damage must have taken place in the starting cage.

Sławomir Szymaniec

Politechnika Opolska

ASPEKTY METROLOGICZNE DIAGNOSTYKI PR DOWEJ SILNIKÓW

ELEKTRYCZNYCH

THE METROLOGICAL ASPECTS OF CURRENT DIAGNOSTICS

OF THE ELECTRICAL MOTORS

Abstract:

This paper describes the metrological aspects of current diagnostics of the electrical motors. The author exchanged

most often met damages of motors, which can be diagnosed with taking into consideration measurement and current analysis.

One turned attention on errors commited during of measurements and analyses of current for needs of diagnostics. One talk

overed met in industry arrangements measuring to current diagnostics of electrical motors with used Rogowski coils,

halleffect transducers and current transformers.

Tadeusz Glinka

BOBRME Komel, Katowice

KLASYFIKACJA STOPNIA ZU YCIA IZOLACJI UZWOJE

MASZYN ELEKTRYCZNYCH

CLASSIFICATION OF ELECTRICAL MACHINES WINDINGS’ INSULATION DEGREE OF

WEAR

Abstract: Classification of electrical machines windings’ insulation degree of wear has been presented on the basis of

twenty electrical machines operating in rolling mill. Four of these are synchronous machines, eight are d.c. generators and

remaining eight are rolling mill driving motors. The insulation diagnostic tests include:

measurement of insulation resistance (for steady-state conditions) vs. supply voltage R

=f(U),

measurement of leakage current versus time i

=f(t), after a unit step voltage of rated value was applied ,

measurement of voltage recovery curve U

=f(t); this is measured after the system had been earlier charged with rated

voltage, and then short-circuited for t

seconds.

Basing on the measurements the criteria indices of insulation system are developed; these are set out in Table 1. These indices

help to assess the insulation’s degree of wear according to mark system: from 5 (very good insulation) downto 1 (worn

insulation) – Table 2. Figures 2-4 show the characteristic curves: R

=f(U) (Fig.2), U

=f(t) (Fig.3) and i

=f(t) (Fig.4) for

selected windings, while Table 3 sets out criteria indices for these windings’ insulation.

Zeszyty Problemowe – Maszyny Elektryczne Nr 68/2004

Jarosław Mielczarek

Biuro Projektów i Usług Inwestorskich PRO-MAC

MONITORING STANU IZOLACJI PRZEMYSŁOWYCH

UKŁADÓW NAP DOWYCH

INSULATION MONITORING OF INDUSTRIAL DRIVES

Abstract: This article describes principles of insulation control in electrical networks with drives. Especially phenomenon

caused by frequency converters are taken into account, like DC leakage currents, large earth capacitances, high harmonic

distortions. Methods are described separately for earthed (TN, TT) and for unearthed (IT) systems. Additionally article shows

possibility of continuous insulation condition control of unsupplied motors, to keep them on standby.

Mirosław W siel,

PUP Eltur-Serwis Sp. z o. o.

Janusz Wo niak,

Politechnika Wrocławska

DIAGNOSTYKA EKSPLOATACYJNA NAP DÓW

ELEKTRYCZNYCH DU YCH MOCY – DIAGNOZOWANIE

ŁO YSK TOCZNYCH

OPERATING DIAGNOSTICS OF HIGH POWER ELECTRIC DRIVES

– DIAGNOSING OF ROLLING BEARINGS

Abstract: In many cases the most unreliable elements of driving systems are rolling bearings. Their insufficient durability

makes them one of the sore points taken into consideration when analysing the reliability of the whole equipment. The

variety of the phenomena accompanying the course of wear and tear of the rolling bears makes it possible to use many

diagnostic methods. The paper presents some examples of a diagnostic study of the state of rolling bearings in electric drives

with the use of the frequency analysis of vibrations. Purposefulness of introducing vibroacoustic diagnostics has been

demonstrated, selected operational states of unfitness of electric drives have been presented. The study carried out on the

basis of frequency analysis of vibrations made it possible to observe the progress of damage over time and to identify the kind

of the damage. Pictures of the damaged rolling elements have been presented. They reflect the purposefulness of the decisions

taken. On the basis of the obtained study results the assessment of currently applied methods of operational diagnostics of

rolling bearings was made.

Tomasz Gawro ski, Krzysztof Skulimowski

ZREW S.A.

Wojciech Urba ski,

Politechnika Warszawska

PROFILAKTYCZNE BADANIA SILNIKÓW W DIAGNOSTYCE

PRZEMYSŁOWYCH NAP DÓW ELEKTRYCZNYCH

PREVENTIVE DIAGNOSTIC TESTS OF INDUSTRIAL ELECTRICAL DRIVES

Abstrakt: The article presents, against the background of technical diagnostics development, diagnosing and monitoring

methods for equipment and process engineering lines, reliable and offered at present by the Company Zakłady Remontowe

Energetyki Warszawa S.A. (ZREW). These, usually very responsible and sophisticated, technical systems are driven by

electric motors. Many years of experience justifies the selection of, indicated in the paper, physical quantitative, the

measurement of which allows efficient elaboration of a diagnosis. First of all, an important role of the vibration signal in

examination of this type of objects was singled out. The ZREW uses high class equipment and specialised diagnostic

programming. The above-mentioned means make possible, after a logistic reconnaissance of objects, elaboration of proper for

them, diagnostic, monitoring and supervising procedures, and of methods for measurement signals processing. The article

points out the significance of organisation of computer databases and of ergonomic ways of communication with services

performing measurements and with their principals.

Zeszyty Problemowe – Maszyny Elektryczne Nr 68/2004

An important conclusion is the proof of how important is the firm’s quality system for correct performance of diagnostic tests

and for satisfactory cooperation with the company’s customers. In the ZREW it is organised according to the ISO 9001:2000

norm provisions.

Works, performed by the diagnostic staff of the ZREW, bring as the result, every time, lowering of operating costs of

equipment with simultaneous increase of the equipment’s availability and reliability. They influence directly high economic

effectiveness of the company, which ordered the diagnostic tests.

Antoni Nykli ski, Witold Rams,

AGH Kraków

Michał Rams,

Uniwersytet Jagiello ski Kraków

SYSTEM POMIAROWY DO DIAGNOSTYKI

MASZYN I URZ DZE ELEKTRYCZNYCH

MEASUREMENT SYSTEM FOR DIAGNOSTIC OF ELECTRICAL

MACHINES AND APPARATUS

Abstract: The paper presents the diagnostic system made for electric machines and apparatus diagnostic in laboratories and

in the industry. The system is portable and easy to transport. One can use them for tests on rotating machines and

transformers after manufacture or after erection on site in accordance with standard specifications. These tests cover

insulation resistance, winding resistance and impedance and some further tests on different types of machines and apparatus

which are required to meet customer’s requirements or to obtain some particular data. For transformers it is possible to

measure the ratio and to check interphase connection. Each measured value has obtained its uncertainty. Calibration of

system can be done for traceability assurance. System can record and to archive results of measuring. Fourier analysis of

recorded processes is also available.

Maciej Bernatt

BOBRME Komel, Katowice

O AWARYJNO CI SILNIKÓW KLATKOWYCH

WYSOKIEGO NAPI CIA

BREAKDOWNS AND FAILURES OF HIGH VOLTAGE

SQUIRREL CAGE AC MOTORS

Abstract. Break-down rate of high voltage AC squirrel cage motors is not very high. But any failure of large AC motor

involves for its user costs and losses uncomparable higher than the simple cost of repair or even replacing of the motor. In the

paper the main reasons of large AC motors failures are discussed, most of them occur, or at least just begin, at starting period

of the motor (when DOL starting method applied). Possible ways of minimizing break-downs number are presented,

importance of proper diagnostic tests underlined. Two break-down examples: 1000 kW, 1500 RPM and 515 kW, 3000 RPM,

6000 V motor are discussed. After failure both motors were redesigned and renewed at their repair process. After redesigning

the motors work satisfactory.

Jakub Bernatt, Maciej Bernatt

BOBRME Komel, Katowice

EKSPERTYZY I OCENY PRZYCZYN USZKODZE SILNIKÓW

ELEKTRYCZNYCH DU EJ MOCY – CZ.2

EXPERT EVIDENCES AND DEFAULT CAUSES OF LARGE AC MOTORS- part 2

Abstract: The main field of activity of the Research and Development Centre of Electrical Machines KOMEL (Katowice,

Poland) is designing, redesigning and laboratory testing of different kind of electrical machines, mainly AC motors. But

Komel Centre carries out as well: diagnostics, different expert evidences, studies of default causes, especially for large AC

Zeszyty Problemowe – Maszyny Elektryczne Nr 68/2004

motors and driving systems. Expert evidences carried out by KOMEL contain not only a simple list of damages in the

machine concerned, but explain its fundamental cause and the most probable course of events of destruction. Results of this

expert evidences are exploited in designing process, especially for high power machines of high starting and high

performance requirements. In the paper the most interesting study cases for different failures investigated in year 2003 by

Komel Centre are shown. These are failure of 4800 kW slip-ring motor and case of high vibration of 522 kW 2 pole motor.

The paper is a continuation of paper presented in May 2003 during PEMINE Conference[1], where failures of antifriction

bearings, shafts, rotor squirrel cages, stator windings of different AC motors medium and high output have been presented.

The design countermeasures taken by KOMEL to avoid such a failure in further exploitation are proposed.

Szymon Liszka

Fundacja na Rzecz Efektywnego Wykorzystania Energii, Katowice

ZAANGA OWANIE RODKÓW GLOBALNEGO FUNDUSZU OCHRONY

RODOWISKA (GEF) W DZIAŁANIA ZMIERZAJ CE DO RACJONALIZACJI

ZU YCIA ENERGII ELEKTRYCZNEJ

W POLSCE -

POLSKI PROGRAM EFEKTYWNEGO WYKORZYSTANIA ENERGII W

NAP DACH ELEKTRYCZNYCH (PEMP)

POLISH ENERGY EFFICIENT MOTORS PROGRAM - PEMP.

GLOBAL ENVIRONMENTAL FUND FINANCING ENERGY EFFICIENCY

IN ELECTRIC MOTOR SYSTEMS IN POLAND

Abstract: After six year of preparation phase Polish Energy Efficient Motors Program - PEMP was approved and signed by

Global Environment Facility (GEF). In the article the way the project was developed and final shape of the implementation

phase of the project is described. Description focuses on the PEMP Center which is responsible for the capacity building and

awareness activity, such as:

- establish a sustainable institutional mechanism for the provision of information and services for the energy efficient electric

motors market;

- gather and provide information on the energy efficient motors market in Poland, thereby establishing a market baseline and

providing a resource on market activities and a source of information for benchmarking;

- document and compile information on the benefits of energy efficient motors;

- provide technical and business advisory services for pilot projects and business project development;

- train project developers, industry, and financial institutions on energy audits, feasibility studies, funding applications, etc.

Stefan Gierlotka

KWK Wujek, Katowice

ZAGRO ENIA PORA ENIA PR DEM POWODOWANE MASZYNAMI

ELEKTRYCZNYMI WYŁ CZANYMI Z RUCHU

DANGER OF ELECTRICAL SHOCK CAUSED BY SWITCHING OFF ELECTRICAL

MACHINES

Abstract: The paper describes danger of electrical shock caused by rotating electrical motors after switching them off. When

the motor rotates after cutting off the supply voltage the dangerous voltage (U > 50 V) remains in the motor and in the cable.
The measured voltages after switching off motors of output 36

÷ 400 kW indicate that the time with electrical shock danger

is 1,2

÷ 5,3 seconds.

Zeszyty Problemowe – Maszyny Elektryczne Nr 68/2004

Jerzy Szyma ski

Politechnika Radomska

OCHRONA PRZECIWPORA ENIOWA INSTALACJI NAP DOWYCH Z

NAPI CIOWYMI PRZEMIENNIKAMI CZ STOTLIWO CI ZASILANYMI Z

SIECI TN-S DO 1 kV

ELECTRIC SHOCK SAFETY IN INDUSTRIAL MOTOR DRIVE INSTALLATION WITH

VOLTAGE FREQUENCY CONVERTER SUPPLIED FROM TN-S POWER SYSTEM UP TO

1 kV

Abstract:

Voltage frequency converter for driving systems is complicated power electronic device, in aspect of assurance

proper protections against electric shock. Increases it large difficulties at designing and building of it power supply system.

In this paper author passed analysis of supply power system with drive VFC in rules of electric shock protection, according

to norm IEC 60364. One proposed realization of additional shock protection in typical installation, is only by use quick

disconnection of VFC from power supply by fuses and proper drive equipments connection to the earth. Proper appointment

of impedance loop of short-circuit on VFC power supply connectors has basic meaning for selection value of input quick

fuses. Using connections to earth of VFC protective connector PE with little impedance for high frequency waves, indeed

limits disturbances about radio frequencies emitted to environment. In normal work of these drive systems accrues high

frequencies currents which dependents from VFC configuration and conditions of installation work. These currents make

impossible usage high sensitive RCD switches. In supplement safety protection only, as protection against fire, author

allows usage of RCD switches type A with earth currents from 100 - 500mA. This paper can have controversial discuss

because positions different specialists are here strongly not uniform.

Mieczysław Zielichowski, Tomasz Szlezak

Politechnika Wrocławska

BEZPIECZE STWO EKSPLOATACJI GENERATORÓW ZE WZGL DU NA

ZAGRO ENIA ZIEMNOZWARCIOWE

GENERATORS EXPLOITATION SAFETY IN RESPECT OF GROUND-FAULT HAZARDS

Abstract: Optimization of operating conditions of ground-fault protection systems for unit-connected generators may be

achieved solely after estimation of effects of ground-faults in generator stator winding, with simultaneous consideration both

stator core and insulation damages, and ground-fault overvoltages. In this paper estimation of ground-faults effects in

generators with neutral isolated and grounded through resistor was presented. Both ground-fault damages and ground-fault

overvoltages were considered. The analysis was performed for 200MW unit-connected generator running in domestic power

system.

Tadeusz Glinka, Mieczysław Jakubiec, Wojciech Poprawski

BOBRME Komel, Katowice

ENERGOOSZCZ DNO NAP DÓW O REGULOWANEJ PR DKO CI

OBROTOWEJ

ENERGY-SAVING VARIABLE SPEED DRIVES

Abstract: Energy-saving electrical drive (Fig.1) is the type of drive working at its minimum required rotational speed (1).

The algorithm of energy-saving drive operation can be applied to (Fig.2):

- d.c. motor with electromagnetic excitation,

- d.c. motor with permanent magnet excitation (Fig.4),

- cage induction motor,

- brushless motor with electronic commutator.

The paper gives the comparison of these four motor types.

Zeszyty Problemowe – Maszyny Elektryczne Nr 68/2004

The comparison criterion is the motor’s volume, i.e. all the motors have identical outer dimensions as shown in Fig.3. If it is
assumed that during steady-state operation the active power loss in all motors is kept constant

∆P 4900 W, then each

motor’s ratings (power and efficiency) are different (Table 1). The brushless motor is characterized by highest rated power

(77 kW) and efficiency (94%). If rated power of brushless motor is decreased down to 53 kW, i.e. to the induction motor

rated power value, then power loss in brushless motor drops down to 2300 W, and the efficiency rises to 95,8%.

Zbigniew Szulc, Jerzy Przybylski

Politechnika Warszawska

TECHNICZNE I EKONOMICZNE ASPEKTY ZASTOSOWANIA

SOFT-STARTU DO SILNIKA INDUKCYJNEGO KLATKOWEGO

O MOCY 3,7 MW I NAPI CIU 6 kV

TECHNICAL AND ECONOMICAL ASPECTS OF THE APPLICATION

OF THE SOFT-START FOR INDUCTION MOTOR 3,7 MW/6 kV

Abstract: This paper presents technical and economical effects after applying a soft-start to the 3,7 MW, 6kV squirrel-cage

motor driving paper refiner. The soft-start is voltage controller based on phase controlled SCR. Simulation and practical

results after a nine-month exploitation confirmed that proposed solution achieved preliminary requirements like: current limit

and decrease of pulsating torque during the first few seconds of starting the motor. These requirements allowed to increase

motor lifetime and to eliminate the necessity of reconfiguration power grid before starting the motor. Additional economical

effect is a possibility of saving energy due to decreasing the idle run time of the drive.

Bronisław Firago,

Białoruska Pa stwowa Akademia Techniczna w Mi sku

Leszek Pawlaczyk,

Politechnika Wrocławska

DOPUSZCZALNY MOMENT SILNIKA INDUKCYJNEGO

W PRZYPADKU STEROWANIA CZ STOTLIWO CIOWEGO

THE CONTINUOS USABLE TROUGE OF A FREQUENCY – CONTROLLED INDUCTION

MOTOR WITH THE SELF - VENTILATION

Abstract: The article deals with the determination of the continuous usable torque for a frequency - controlled induction

motor with the self – ventilation and stabilization of the magnetic flux linkage. The developed technique takes into account

the heating power losses and the ambient temperature. On the basis of this technique takes into account the continuous steady

state electromagnetic torque can be calculated for a given frequency of the induction motor including a standstill condition.

The results of calculations for three induction motors of 3, 55 and 160 kW are presented in curves: torque versus frequency.

Stanisław Azarewicz, Adam Zalas

Politechnika Wrocławska

CZ STOTLIWO CIOWE STEROWANIE NAP DÓW PO REDNICH

PRZENO NIKÓW TA MOWYCH

FREQUENCY STEERING OF INDIRECT DRIVE FOR BELT CONVEYORS

Abstract:

Indirect drive in long belt conveyors can lessen the stresses in the belt and in the load bearing structure of the

conveyor because of the distribution of the belt

′s pulling force into several components of force. The indirect drives without

pouring point are interesting solutions both from the technical, and the economical points of view. Most frequently used

solution is an auxiliary conveyor which drives the runners of the main conveyor. The problem in manufacturing this sort of

drives is both the variability of thermal compression between the belt and runners in belt load function, and the necessity to
adjust the driving velocity of the auxiliary drive

′s motor to the current parameters of the main belt′s load. All these

requirements cause the driving motors of the auxiliary drive to be powered from the frequency converter Typical methods of

Zeszyty Problemowe – Maszyny Elektryczne Nr 68/2004

frequency changer control do not always provide satisfactory results in the difficult working conditions of the auxiliary

drives, the use of positioning system of induction motors was suggested. Conducted laboratory tests of the drives showed the

advisability of usage of machine tool motor for the realization of indirect drive for belt conveyors.

Jadwiga Płoszy ska

Politechnika Rzeszowska

DYSKUSJA NIEPO

DANYCH ZJAWISK

WYST PUJ CYCH W SILNIKACH INDUKCYJNYCH

DISCUSSION ON UNDESIRABLE PHENOMENA OCCURED

IN INDUCTION MOTORS

Abstract: During operation of squirrel-cage motors, undesirable phenomena can be observed. They influence on the life of

motors and have an unfavourable influence on the environment. Duration, place and intensity of occurrence of these

phenomena are diverse. Complete elimination of reasons of the side-effects is not possible. The aim of detailed recognition of

undesirable phenomena in induction motors is an explanation of reason of their formation and to show the actions leading to

their minimization.

Trial of systematization of undesirable phenomena occurring in induction motors was undertaken in the article. During

systematization, place of occurrence and reasons of phenomena were taken into account. The results demonstrated during

steady state and starting of motor were shown. Taking into account the place of occurrence, the zone of gap of magnetic

circuit, the part of squirrel-cage winding outside the sheet pack, sheet pack of rotor core and bearings should be considered.

The effect of flow of large starting current is emission of considerable amount of energy in the squirrel cage winding of the

rotor. This energy causes thermal effects. During steady operation, the undesirable effects in the form of decreased efficiency,

increased noises and vibrations, deformed mechanical characteristic, flow of crosswise currents in the pack of rotor, may be

expected in the process of conversion of electric energy.

Tomasz Zawilak, Ludwik Antal, Jan Zawilak

Politechnika Wrocławska

ROZRUCH SILNIKÓW INDUKCYJNYCH

Z ROZDZIELONYMI UZWOJENIAMI STOJANA

START UP OF INDUCTION MOTOR

WITH TWO SEPARATED STATOR WINDINGS

Abstract: This paper presents a method of attenuating start up processes of high power AC motors. In this method two

separated thee-phase windings are used. During start up one of the winding is supplied from the network and the second one

is connected to capacitor bank. Reactive component of the starting current is partially compensated by secondary winding

current that is caused by transformation voltage. A mathematical model of this motor is presented. There were made

calculations of transient characteristics which are compared to measured transients of manufacturing model.

Ludwik Antal, Jan Zawilak

Politechnika Wrocławska

WYNIKI BADA DWUBIEGOWEGO

SILNIKA SYNCHRONICZNEGO

TWO SPEED SYNCHRONOUS MOTOR TESTING RESULTS

Abstract: The work presented testing results of a 600/1050kW, two-speed synchronous motor, with two synchronous speeds

500 and 600 rev/min. destined to drive a main mine ventilating fan. The excitation winding of the tested motor may be

connected using 8 or 10 poles. Theoretical evaluation as well as tests results conclude that a complete disconnecting of two

poles has a positive influence on motor’s work at lower speed and negative on work at higher speed. The conducted tests

Zeszyty Problemowe – Maszyny Elektryczne Nr 68/2004

permitted an assessment of motor work quality at each of the two speeds. During tests, voltage, armature and excitation

currents course as well as direct start-up, steady asynchronous speed, synchronization and motor loading were recorded for

both rotating speeds. Armature current recording and harmonic analysis of these courses showed the degree of current

deformation caused by asymmetry of the excitation circuits, which is the condition to obtain the second, lower rotating speed.

An asynchronous run with small slip, permitted to establish motor’s synchronous reactance in both its axis. Two-step starting

of a two-pole motor is characterized by lower than a single pole motor starting current. Vibration measurements had shown

that the vibration level is higher than in a single pole motor. Thermo-visual temperature measurements demonstrate that the

maximal temperature appears on some bolts of the stator core and is higher at lower speed operation. The increased values of

vibration and temperatures of the tested two-pole motor do not exceed the permitted values.

Tadeusz Glinka, Mieczysław Jakubiec, Robert Rossa

BOBRME Komel, Katowice

SILNIKI SYNCHRONICZNE O ROZRUCHU ASYNCHRONICZNYM

LINE START SYNCHRONOUS MOTORS

Abstract: In this paper a new concept of line start synchronous reluctance motor (LSRM) and line start synchronous

reluctance motor co-excited by permanent magnets (LSRMPM) is shown. The paper describes construction and shows

parameters of LSRM and LSRMPM also comparing them with parameters of induction motors (IM). The main advantage of

these motors is asynchronous start-up and synchronous operation. While the LSRM have got lower output than IM of the

same cubature, the LSRMPM have the output equal to IM. It allows to use the LSRM and LSRMPM in all drives requiring

the constant speed (not depending of the load) or in group drives where all motors must work together synchronously. Since

the excellent working parameters the LSRM and LSRMPM are subject of number of patents (pending).

Tadeusz Glinka, Artur Polak

BOBRME Komel, Katowice

MAGNESOWANIE MAGNESÓW TRWAŁYCH

- MO LIWO CI LABORATORIUM BOBRME KOMEL

MAGNETISING OF PERMANENT MAGNETS IN LABORATORY OF KOMEL CENTRE

Abstract: Magnetising of NdFeB permanent magnets is performed in electromagnetic circuit shown in Fig.1. Charged

condenser battery acts as a source of pulse magnetizing current – Fig.2. Exciter’s current, which flows after the charged

condenser’s battery is switched on reaches its maximum value, along hyperbolic sine (Fig.4a) or cosine curve (Fig.4b).

Current change is aperiodical, with exciter’s electromagnetic time constant. Laboratory of Komel Centre uses condenser

battery of maximum energy equal to 9600 J. The battery consists of four sections (Fig.5), which can be connected: in parallel

(120 mF, 400 V), in mixed connection (30 mF, 800V) or in serial connection (7,5 mF, 1600 V).

Jakub Bernatt

BOBRME Komel, Katowice

WYKORZYSTANIE PR DNIC SYNCHRONICZNYCH DO BUDOWY

MAŁYCH ELEKTROWNI WIATROWYCH

SYNCHRONOUS ALTERNATOR USED IN CONSTRUCTION

OF SMALL WIND-MILLS

Abstract: The paper describes small a wind-mill built by a farmer. The synchronous alternator with permanent magnets

manufactured by Komel was implemented in this wind-mill. Electricity produced by the wind-mill is consumed for heating

purposes (water and house). It is stated that use of synchronous alternators in small wind-mills is necessary for satisfactory

performance of the wind power station. The alternator used in the described wind-mill is characterised by low rotating speed

Zeszyty Problemowe – Maszyny Elektryczne Nr 68/2004

to reduce power loses in gear box. Synchronous alternator with PM is self excited and can supply separated grid. It can be

overloaded even by 50% without any damage.

Author’s intention was to show that construction of the wind-mill for self use of electricity is easy and not expensive, but

special attention to rotor of the wind-mill and to alternator should be paid.

Ryszard Dziworski

Lubelska Wytwórnia D wigów Osobowych Lift Service S.A.

METODYKA POMIARÓW I OCENA ENERGOCHŁONNO CI

ELEKTRYCZNYCH NAP DÓW D WIGÓW OSOBOWYCH

METHODS OF MEASUREMENTS OF THE ENERGY CONSUMPTION

IN ELECTRICAL DRIVE SYSTEMS IN LIFTS

Abstract: In above report there were presented methods of measurements the energy consumption and the intensivity of

exploatation the different drive systems in electrical lifts as well as the preeliminary summary of the measuring results done

on four lifts.

Here are presented the most important calculated faktors received as the result made measurments by using specjally created

to this purpose measurement devices.

Ryszard Rut

Politechnika Rzeszowska

SKUTECZNO OBNI ENIA HAŁASU

W SILNIKACH WYSOKIEGO NAPI CIA REDNIEJ I DU EJ MOCY

EFFICIENCY OF NOISE REDUCTION IN MIDDLE AND HIGH OUTPUT

HIGH VOLTAGE AC MOTORS

Abstract:. Large part of high power electric motors used in polish industry are at least 20-30 years old products. The motors

were designed in 60-ties or 70-ties of the last century. Noise level of industry machinery was regarded as of minor importance

in those days. Replacing a high voltage, high power motor just because of its noise level is not always economically justyfied.

In the paper methods of diminishing of the noise level of high voltage induction motors are given, several examples are

presented, as well.

Roman Krok, Politechnika l skia

Janusz Wróblewski,

D browska Fabryka Maszyn Elektrycznych „DAMEL” S.A.

BADANIA WPŁYWU ZMIAN WARUNKÓW CHŁODZENIA

NA STAN CIEPLNY SILNIKÓW INDUKCYJNYCH

PRACUJ CYCH W PODZIEMIACH KOPAL

INVESTIGATIONS OF THE INFLUENCE OF COOLING CONDITIONS

CHANGES ON THERMAL STATE OF INDUKTION MOTORS WORKING

IN COAL-MINE UNDERGROUND

Abstract: The paper presents a model for calculating temperature fields in water-cooled induction motors. The model was

worked out basing on the method of thermal-electrical networks. It was the basis for developing the computer program for

thermal investigations of mine motors. In order to determine the accuracy of representing the thermal state of a motor by

means of the worked out model there were made thermal measurements of the motor. Thermal investigations of mine motors

of 400 kW working in coal-mine underground were performed by means of the computer program. The influence of changes

of load as well as parameters characterizing operating conditions (for instance: the ambient temperature, the temperature

of water at the inlet to the frame) on the thermal state of the motor was determined basing on the obtained results of the

simulation investigations.

Zeszyty Problemowe – Maszyny Elektryczne Nr 68/2004

Jurij Czuczman, Denys aksimovicz

Uniwersitet Narodowy „Politechnika Lwowska”

MODERNIZACJA UZWOJE WSYPYWANYCH SILNIKÓW

ASYNCHRONICZNYCH PODCZAS REMONTÓW

THE ANALYSIS OF THE USE AND MODERNIZATION OF INDUCTION MOTORS WITH

FILLING WINDINGS DURING THE REPAIR

Abstract:

This article deals with the interrelationship of performance characteristics of the induction motors with the fillings

windings that are dependent on the type of windings which are used during the repair.

In order to decrease the labor-

intensiveness of the technological process one could make wider use of a lathe for the mechanized working of this kind of

motors. At the same time it could cause an increase in the losses in the magnetic wires, the size of power loss, the decreasing

of its reliability, and the term of its operation.

This type of motor could be mainly repaired by service station whose

technological equipment is different from the equipment of big businesses. A solution for all of these problems could be a

process of modernization of the stators’ windings during the repair. This modernization includes the replacement of single-

layer or single-double-layer concentric windings in favor of single-layer equipment windings or double-layer windings.

There

are examples of the realization of the different types of windings that could provide the minimization of copper use without

increasing the labor-intensiveness of the procedure. At the same time it provides the decrease of power lose in the motors

with invariably power factor.

Henryk Borecki

ENERGOKONSULTING Lubliniec

ROZWÓJ LOKALNYCH WYŁADOWA ELEKTRYCZNYCH

W IZOLACJI MI DZYZWOJOWEJ STOJANA

HYDROGENERATORA

DEVELOPMENT OF LOCAL ELECTRICAL DISCHARGES

IN HYDROGENERATOR TURN-TO-TURN STATOR INSULATION

Abstract: Voltage distribution in gaseous solid or liquid inclusions is determined by local capacities. Author made studies

and tests of turn-to-turn insulation of a stator coil of hydrogenerator, using DC test method. Results are presented in the

paper.