Английский язык для моряков / Труханова Англ для моряков

instruments readings показания приборов

QUESTIONS

1.What do the service life and reliability of the electrical equipment depend on?

2.What does watch maintenance include?

3.What is meant by normal operation of the electric machines?

4.How is trial start performed?

5.What must be included into checking the generators working in parallel?

6.What should the watch personnel observe while checking the shaft generators?

7.What must be done before starting the electric motor?

8.What does the electric drive examination include?

2. ELECTRICAL MAINTENANCE

Electrical maintenance consists in ensuring safe operation of shipboard electrical equipment and stability of its performance characteristics between factory overhaul periods.

Electrical maintenance is to be performed in accordance with Regulation on Operation and Maintenance of Merchant Marine and guided by a maintenance schedule.

Periodicity and labour-intensiveness of work as well as the maintenance staff intended to do it are all set by a standard maintenance schedule and to be corrected, relying on the actual state of assemblies of electrical machines in compliance with their operating conditions.

The state of assemblies and parts of electrical machines is assessed on the strength of the data on the value and change of 1) insulation resistance, 2) heating, 3) moistening, 4) brush sparking, 5) vibration, 6) noise, 7) gaps in sleeve bearings, 8) axis runs of rotor shafts, 9) airgaps of interiron space as well as on the state of 10) commutators (sliprings), 11) brushes, 11) bearings, 13) bandages, 14) bracings on the commutator shaft.

In order to keep electric machines in operating condition preventive maintenance in provided. There are three basic ways of preventive maintenance with which:

1)electric machines remain assembled;

2)electric machines are partially disassembled;

3)electric machines are completely disassembled.

Preventive maintenance of electric machines which remain assembled or are partially disassembled may be executed either while the ship is running or staying in a scheduled port. The electric drives involved in maintenance while the ship is running are those of cargo-lift- ing mechanisms, which possess a standby. Those included in maintenance during the ship's stay in the port are electric drives of the mechanisms which work continuously, ensure ship's safe running and have no standby. The electric drives of steering gears relate to them, as an example.

Maintenance provided for electric machines which remain assembled incorporates their cleaning in available places. The loosened attachments are tightened, the brushes are replaced, the brushgear is partially adjusted, the commutator and slip-rings are cleaned, the lubrication of bearings is substituted, the insulation resistance is measured.

Once the fault cannot be remedied with a machine which remains assembled, the latter is partially or completely disassembled. Minor

repair, not pertaining to rewinding and re-impregnation of windings, i carried out by a ship's crew. Major damages are dealt with in electric; workshops of ship-repairing factories. These latter also replace windinqs insulation.

QUESTIONS

1.What does electrical maintenance consist in?

2.In accordance with what is electrical maintenance to be performed?

3.What is set by a standard maintenance schedule?

4.What data are needed to assess the state of assemblies and parts of electric machines?

5.What are three basic ways of preventive maintenance?

6.Why are the electric drives of cargo-lifting mechanisms maintained while the ship is running?

7.Why are the electric drives of steering-gears maintained during the ship's stay in the port?

8.What maintenance is provided for electric machines which remain assembled?

9.Is minor repair carried out by a ship's crew?

10.Where are major damages dealt with?

3. TESTING ELECTRIC MACHINES FOR DEFECTS AND CARRYING OUT REPAIRS.

CURRENT REPAIR

Electric machines are tested for defects before being repaired. The procedure of testing for defects results in filling a detailed repair request form and making up a repair list which contains a machine registration certificate, a number of detected defects and repairs intended to correct them. The list of materials, spare and component parts, wiring accessories needed for repairs are also included in the list. The latter equally identifies the type of repair - either it is current (running) or capital (overhaul).

Current repair of a D.C. machine can be performed in two ways - either the machine poles are removed or not removed.

When the machine poles are not removed, the current repairs involves the following procedures:

1. Disassembling a machine;

2.Cleaning a machine;

3.Blowing through and washing out inner parts, bearings, а commul tator and a brushgear;

4.Detecting and eliminating minor defects;

5.Replacing bearings;

6.Slotting and grinding a commutator;

7.Drying, enamelling and redrying windings;

8.Partial repair of a brushgear with replacing and grinding brushes;

9.Assembling a machine, adjusting and testing it on a test bed;

10.Mounting a machine on a machine bearer and testing it foil operation.

When the machine poles are removed, the current repair addition4 ally provides the

following:

11.Removing the main and commutating poles with coils;

12.Disassembling, cleaning and washing poles;

13.Drying and impregnating coils with varnish;

14.Replacing and repairing defective insulative gaskets;

15.Restoring micanite gaskets of pole cores;

16.Checking insulation resistance of coils;

17.Assembling, mounting and testing pole coils for polarity. Current repair of an a.c. synchronous or asynchronous machine

involves the same procedures as that of a D.C. machine, but the poles! are never removed as well as commutator is not placed under repair. The brushgear, however, of both a synchronous machine and an asynchronous phase motor is laid under partial repair.

1. What happens to electric machines before they are repaired?

2.What does the procedure of testing for defects result in?

3.What information does the repair request form contain?

4.What ways can current repair of a D.C. machine be performed in?

5.What are the procedures that are involved in current repair when the machine poles are not removed?

6.What are the procedures that are included in current repair when the machine poles are removed?

7.Is there any difference between capital repair of a D.C. machine and that of an a.c. machine?

8.Is the brushgear of an a.c. machine laid under repair?

4. CAPITAL REPAIR OF D.C. AND A.C. MACHINES

Capital repair of electric machines is basically carried out in electrical workshops of ship-repairing

factories.

Capital repair of a D.C. machine is predominantly performed with the following procedures:

1.Disassembling a machine with removing its armature, poles with coils, bearings;

2.Complete or partial rewinding of windings with replacing wedges and slot insulation;

3.Impregnating a winding with varnish, drying, enamelling and redrying it;

4.Disassembling and removing the commutator with replacing micanite gaskets between commutator plates and cone micanite insulation;

5.Assembling a commutator on a shaft by a pressed fit, turning it on a lathe, slotting, grinding and polishing it;

6.Replacing armature bandages and performing static balance;

7.Rewinding a half of both the main and commutating poles, repairing the others, drying, impregnating them with varnish, drying them and enamelling pole coils;

8.Mechanical repair of a brush-rocker and brush-holders as well as restoring galvanic coating on the

parts;

9.Assembling a machine, grinding its brushes on a commutator, checking gaps;

10.Adjusting, testing a machine on a test-bed, mounting it on its bearer and testing for operation.

Г

Capital repair of an a.c. machine includes partial or complete rewinding of both the stator and the rotor. Damages in a cage motor those of its legs and end rings - are corrected as well. Generator exciters are also placed under repair and the latter is carried out in much the same way as that of a D.C. machine.

QUESTIONS

1.Where is capital repair of electric machines basically carried out?

2.What are the procedures of capital repair of windings?

3.what are the procedures of capital repair of a commutator?

4.What are other procedures?

5.What is the principal difference between capital repair of a D.C. machine and that of an a.c. machine?

6.What damages in a cage motor are corrected?

7.How are generator exciters in an a.c. machine repaired?

EXERCISES

1. Think of English equivalents for suggested Russian words and word combinations and complete the

sentences:

1.__________ (срок службы и надежность) of electrical

___ _______ ____ (в режиме холостого хода).

The ____________ (вахтенный персонал) should observe the generator drive condition and ___________________ J

(колебания частоты и напряжения) while working with (валогенераторы).

assessed on the strength of the following data.

8.In order to keep electric machines in __ _ ____

9.The electric drives involved in maintenance while the ship is running are those of

(грузоподъемные

механизмы) which possess a ________ (резерв).

10.The_____________ (ослабевшие крепления) are tightened,

the________ (щетки) are replaced, the________ (щеточный аппарат) is adjusted, the

__________ (сопротивление изоляции) is measured.

лия) needed for repairs are also included in the repair request form.

14. The procedure includes ___ ___ ____ (продоражи-

вание и шлифовка коллектора) as well as ___

(продувка и промывка подшипников).

15.Any repair starts with___________(разборка и чистка машин).

16.Any repair finishes with______ ___ ___________

(сборка, испытание машины на стенде, проверка в работе).

с короткозамкнутым ротором) - those of its__ (стержни) and (замыкающие кольца) - are rectified as well.

20. After assembling a machine the workman must grind its brushes on the commutator and check the (зазоры).

II. Choose one of the linking words or word combinations from the box and complete the sentences.

1.Magnetism is the property of the molecules of iron and other cdj tain substances _______ which they store energy in a field.

2.Alternating current is an electric current that changes _____ I directionmagnitude at fixed intervals of time.

3.The resistance of metals increases with the increase in the tempe; ature, ______ the resistance of insulating materials decreases. 1

7.Shunt, series and compound generators are self-excite;'

________ they don't require a separate current source for the excitation.

________ in the figure, curve 3 passes above no-load curve.

9.They aren't remagnetized _______ the unchangeable current rection in the field winding.

10.__________ overcome this force, the external force should exerted upon the generator circuit.

11.Such a current is dangerous for the armature winding and a machl

12.It is attained by changing the field current ________ an adjust! rheostat placed in series with the armature circuit.

13.The speed of rotation is altered moderately - predominant ___________ the voltage drop in the armature.

14.The starting torque of the motor is rather small, directly proportio

to the armature current; ________ the current consum from the mains is proportional to the load on the shaft.

15 . _______ its capacity, a rotary amplifier may operate as eithf an exciter or a generator.

UNIT 9. ELECTRICAL SAFETY

1. THE MAIN REASONS OF ELECTRICAL TRAUMATISM AND MEANS OF PROTECTION

AGAINST IT

The main reasons of electrical traumatism on board ships are the following:

■rough infringement of Rules of both shipboard electrical maintenance and electrical safety;

■live-line maintenance without observing protective measures;

■imperfection of operation manual of electrical mechanisms (those of deck machinery, engine-room

etc.);

■imperfection of construction of wiring accessory;

■faultiness and imperfection of portable accessory and portable tools;

■lack of uniformity in the choice of voltages of start regulating equipment control circuits;

■unsatisfactory condition of the mains electrical insulation;

■ill-timed elimination of the troubles and damages of the electrical equipment occurred;

■formal instructing on safe methods of work.

The use of electrical energy on board ships is not only associated with the danger of electric shock hazard of an operating personnel but also with possible fires.

Under normal conditions a thermal effect of an electric current is rated, i.e. the heating of conductors and current-leading parts of the electrical equipment is calculated so that it not exceed fixed rates.

If the Rules of shipboard electrical maintenance and safety are notj observed, if damages occur and the environmental conditions (dampness, dust, chemically active substances) affect the electrical equipment, its normal state is broken. On electrical sets there emerge short-circuits, overloads, large transient resistances, arc and spark discharges, which can also cause fires.

To protect an operating personnel of electrical sets against electricshock hazard there exist principal and additional protective means.