Тест по дизельному генератору (CES v5.0)

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Правильні відповіді:
1

During the parallel operation of generators, the operator adjusts the diesel generator no. 1’s potmeter in the main switchboard to a higher resistance. What will happen?

Ваша відповідь правильна:

The reactive load on diesel generator no. 1 will increase.
2

How could you monitor the correct instant for synchronizing without the aid of a synchroscope or synchronizing lamps?

Ваша відповідь правильна:

By connecting a pair of voltmeter probes across one phase of the incoming generator circuit breaker, and then adjust the generator speed until the voltmeter slowly fluctuates from zero to maximum. Connect the breaker when the voltmeter passes through zero.
3

How many % of nominal voltage is required before main circuit breaker can be connected to main bus bar?

Ваша відповідь правильна:

70 %.
4

How many degrees are there between the phases in a 3-phase generator?

Ваша відповідь правильна:

120°.
5

If we have a generator with 4 poles, how many rpm does it need to give 60 Hz?

Ваша відповідь правильна:

1 800 rpm.
6

In a winding, which rotates in a magnetic field, the induced voltage is:

Ваша відповідь правильна:

At its highest when the flux is at its lowest.
7

In this module we will use a diesel engine with 1 200 rpm, 60 Hz as the primary mover for the alternator. How many pole pairs are present in the alternator?

Правильну відповідь:

3 poles.

Ваша відповідь:

2 poles.
8

Normally the power factor on the generator is:

Ваша відповідь правильна:

0,8-0,9.
9

The 700 kW generator circuit breaker has an over-current trip setting of 125 %. What will the actual minimum tripping current level be, when the power factor is 0,85?

Ваша відповідь правильна:

1 352 A.
10

The diesel generator no. 1 has recently been through a major overhaul. During the running-in period, we do not want the engine to take full load. What do you do?

Ваша відповідь правильна:

Change the max load setting on the governor.
11

The generators are run in manual, and when you discover that the DG no. 1 takes a larger part of the active load than DG no. 2, what could you do to share the load equally between the generators?

Ваша відповідь правильна:

Increase the DG 2 and decrease DG 1 by means of the governor control switch.
12

The kW and kVAr instruments on the main switchboard reads respectively 630 kW and 400 kVAr. What is the actual power factor?

Ваша відповідь правильна:

0,85.
13

The nominal frequency is 60 Hz at 1 200 rpm and speed set point (idle speed) is set to 1 200 rpm. What is the speed and frequency at 80 % load, when the speed drop is set to 4 %?

Ваша відповідь правильна:

1 161,6 rpm, 58,08 Hz.
14

What could be the probable cause if the reactive load sharing is balanced at low loads (up to 50 %), but imbalanced at higher loads?

Ваша відповідь правильна:

Loose connection or broken diode in one of the diode bridges. This will cause the regulator to increase the output to achieve UN = UG. The regulator can manage this at low loads, but a higher loads the capacity is not sufficient to compensate for the loss of one diode.
15

What does it mean if the synchronizing lamp rotation is counterclockwise?

Ваша відповідь правильна:

Generator frequency is to slow relative to main bus.
16

What is the minimum requirement of isolation resistance for a 440 V system?

Ваша відповідь правильна:

440 kilo Ohm.
17

What is the probable cause if the generator loads are balanced at low loads, but imbalanced at higher loads?

Ваша відповідь правильна:

Dirty fuel oil filter on the diesel generator taking the smallest load.
18

What will happen if load dependent start/stop of generator sets is in auto mode?

Правильну відповідь:

It will start/stop the generator sets in response to varying load.

Ваша відповідь:

It will start but never stop the generator sets in response to varying load.
19

Where will you find the instruments for synchronizing the generator?

Ваша відповідь правильна:

On the main switchboard.
20

Which control mode is recommended during manoeuvring?

Ваша відповідь правильна:

Equal, because of the wider control range, which allows the low priority generator(s) to be connected at low loads.
21

Which of the following loads has the most negative effect (weaken) on the main field, and in doing so lowers the induced voltage in the generator?

Ваша відповідь правильна:

Inductive load.
22

Which statement is true?

Правильну відповідь:

The Priority 1 generator will be first IN/last OUT.

Ваша відповідь:

At Cyclic control mode the generators change Priority order.
23

Which statement is true?

Правильну відповідь:

When automatic frequency control is selected, the “follow-up” will parallel shift the speed drop until the generator frequency = nominal frequency.

Ваша відповідь:

The Start/Stop request alarm activates and stops the diesel at low LO pressure.
24

Which statement is true?

Ваша відповідь правильна:

For quick regulation at connection of large consumers, the load dependant primary winding produces an output corresponding to 120 % of nominal voltage.
25

Which statement is true?

Ваша відповідь правильна:

An engine room fan is considered an inductive load.
26

Why do we press the connect button when the synchroscope shows “5 to 12”?

Ваша відповідь правильна:

Because of the time delay (the time from pressing the button until the breaker is connected).
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