2. If the first set does not succeed in switching onto the busbars,
(a) the automatic equipment will start a certain number of diesel alternators; b) it is then advantageous to have at least one additional alternator about to be synchronized onto the busbars; c) it will be blocked and the next is allowed to make the attempt, etc.
3. .. .is sensed by the automatic equipment by the fact that there is no voltage on the busbars and that all breakers are tripped, (a) delaying the clearing of the black-out condition; b) the black-out condition;
c) switching onto the busbars.
Now record your time and results. Compare them with ‘ previous ones.
39 15
Work in pairs. Dwell with your fellow-student on work with automatic control system for ships electrical power plants. Mind advantages and disadvantages (if any) of the system. Use ex. 17—19, 22, 24, 35—38.
40 35
Home exercise. Read the text. Write the number of logical units in each sentence. Draw a flow chart of programming of large loads. Make up as many questions on the text as you can and write a summary of it.
Part VII. Programming of Large Loads
If a relatively large load is switched onto the network, a load surge will occur and this may cause overloading and in the worst case, tripping of the circuit breakers due to overcurrent. The risk of not taking this fact into account is illustrated by the starting current of a directly starting induction motor being 5—10 times the rated current.
For preventing such damages automatic control system is provided with unit, designed to control switching in such large loads.
The request for switching in a certain load is made in the form of a closing contact function. The load to be switched in is exceeded, switching in of the load is blocked until conditions render this possible, i. e. until a new diesel has been synchronized onto the busbars. If the power limit is not exceeded, clearance is given for immediate switching in of the load. When the load is switched in, the simulation is switched off, since the load will be metered by the ordinary equipment.
Hometask: Ex. 40.
6 —behkl; 7 —acdeghijknoprtuxyc'; 13—1. Поговорим, как мужчина с мужчиной, что, собственно, здесь произошло? 2. Богат, как Крез, и порочен, как сатана. 3. Все без исключения должны принять активное участие в этой работе. 4. Я далек от того, чтобы так думать. 5. Он считается чуть ли не светилом в этой области науки. 6. Боже мой, почему же я не могу этого сделать! 7. Он не от мира сего. 8. Об этом деле ему известно не меньше, чем кому бы то ни было. 9. Мой дедушка выбился в люди самостоятельно. 10. Я рано вставал и поздно ложился, во всем принимал участие, не уклонялся от опасности, и хоть раз в жизни вел себя, как подобает мужчине. 18 — Remote control system. 2 Safety system. 37 — lb, 2c, 3b; 38—la, 2c, 3b.