Английский язык для моряков / Англ Труханова

VOCABULARY

QUESTIONS

1.What are the main faults that сап Ье observed in а three-phase mo­ tor?

2.Сап you give а list of reasons due to which а three-phase motor fails to start?

3.What should you do if the motor circuit-breaker is defective?

4.How do you test an open phase winding?

5.What should you do if the rotor phase windings are open or make poor contact?

120

6.Why can the rotor Ье caught in the stator?

7.What causes а three-phase motor nominally loaded to run slowly?

8.What measures are to Ье taken to eliminate low voltage at the ter­ minals of the stator winding?

9.What should you check if large resistance is observed on the phase

rotor circuit?

1О. How do you fight а "reversed phase winding"?

11.What causes а three-phase motor to become excessively hot?

12.What should you do if the ventilation channels are c\ogged?

13.What do you do to clean air filters?

14.What are the steps recommended to correct the rotor rotation with

аfan having inclined wings?

EXERCISES

1. Make sure you've properly understood the texts dealing with trouЫesliooting о/ electrical equipment.

1.TrouЫeshooting is the procedure of а) finding а fault;

Ь) e\iminating а fault;

с) both finding and eliminating а fault.

2.Heat and moisture cause: а) rated current flow;

Ь) abnormal current flow; с) minimum current flow.

3.When measuring voltage the electrician must connect the voltmeter:

а) in paral\el with the circuit;

Ь) in antiparal\el with the circuit; с) in series with the circuit.

4.When measuring current the electrician must connect the ammeter:

а) in parallel with the circuit;

121

Ь) in antiparallel with the circuit; с) in series with the circuit.

5.Before applying an ohmmeter the electrician must: а) turn on the power;

Ь) turn off the power; с) turn down the power.

6.If the fuse is open, you should:

а) rewind it; Ь) repair it; с) rep\ace it

7. If а d.c. motor fai\s to run, one of the reasons is: а) shorted armature circuit;

Ь) open armature circuit

с) incorrectly connected armature circuit.

8. If you've found out that the shunt field winding has been incorrect­ ly connected, you should connect it in accordance with: ·

а) а factory mark;

Ь) а factory wiring diagram с) factory instructions.

9.If you've found out that the parallel field winding has been partial­ ly shunted, you should:

а) connect it to other windings; Ь) connect it to the frame;

с) disconnect it from both other windings and the frame.

10.If you observe а differential connection of the shunt and the series windings in а compound motor, you should connect them:

а) in opposition; Ь) in antiparallel; с) accordantly.

11.If the motor ventilation channels are clogged, you should:

а) Ыоw, .them. trough;

Ь) remove dirt from them; с) clean them.

122

12.If the commutator bars are either high or low, you should: а) re-arrange the commutator;

Ь) grind the commutator;

с) set the brushes on neutral.

13.If а three-phase motor fails to start, one of the reasons may Ье:

а) rotor one-sidedly attracted to the stator; Ь) rotor one-sidedly repe\led from the stator; с) rotor one-sidedly fastened to the stator.

14.If you observe large resistance on the phase rotor circuit, the reason may Ье:

а) а defective circuit-breaker; Ь) а faulty rheostat;

с) а wom bearing.

15.lf the temperature of cooling water in an air cooler increases, you should:

а) Ыоw trough ventilation channels; Ь) remove dirt trom air filters;

с) clean the air cooler.

16.If а three-phase motor nominally loaded runs slowly, one of the causes is incorrect voltage at the terminals of the stator winding. It is:

а) rated; Ь) low; с) high.

17.If а d.c. motor runs fast, one of the faults is incorrect voltage at the motor terminals. It is:

а) rated; Ь) low; с) high.

18.If you observe tight bearings, you should:

а) tighten а bearing seal ring; Ь) loosen а bearing seal ring; с) replace а bearing seal ring.

123

П. Choose опе of the linking words or word comblnations from the Ьох and complete t/ie sentences. Some of them are interchange­ aЫe.

1.D.c. machines converting mechanica\ energy into e\ectrica\ one are referred to as d.c. generators. Those, _____ which convert e\ectrica\ energy into mechanica\ one are cal\ed d.c. motors.

2. The series fie\d winding carries the entire arrnature current and

______ its conductors are of large section.

3. The property to which any d.c. rnachine rnay work ___

in а motor rnode __ in а generator rnode is called convertiЬility.

4.Series motors while running id\e don't tend to overspeed ____

their shunt field winding.

5.On board ships, ____ the work safety rules, only air-coo\ed transforrners are used.

6.Their efficiency level is higher ___ that of ordinary transformers of the same frequency.

7.This group of connections revea\s at what angle line lower voltage is shifted clockwise ___ line upper voltage.

8. Fuses are not rnounted if they burn off, the rnagnetic tlux will go up to а dangerous value.

9. The strength of the current in а.с. circuits depends _____

1О. Transforrners rneasuring current and vo\tage are designed to widen they

124

11.The use of autotransformers is prohiЬited, ____, in low voltage portaЫe lighting.

12.The flux and the voltage drop in the field winding are both moderate

13.With the load increase the current value in the field winding and

____ the flux rise.

14.The frame is made of steel _____ of а closed magnetic conductor.

15.The above mentioned stator winding has only one pair of poles,

_____ which the magnetic fie\d does one revolution during one cycle of the current reversal.

16.Static converters are used more widely on board ships ____

rotary converters.

17. the load is increased, the internal voltage drop grows and the speed of rotation drops off.

18. Heat increases the resistance of the circuit and increases the current.

125

GLOSSARY

А

126

127

с

128

129