Тест по дизельному генератору (CES v5.0)

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Right answers:
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?

Your answer is correct:

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?

Your answer is correct:

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?

Your answer is correct:

70 %.
4

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

Your answer is correct:

120°.
5

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

Your answer is correct:

1 800 rpm.
6

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

Your answer is correct:

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?

Correct answer:

3 poles.

Your Answer:

1 pole.
8

Normally the power factor on the generator is:

Your answer is correct:

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?

Your answer is correct:

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?

Your answer is correct:

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?

Your answer is correct:

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?

Your answer is correct:

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 %?

Your answer is correct:

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?

Your answer is correct:

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?

Your answer is correct:

Generator frequency is to slow relative to main bus.
16

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

Your answer is correct:

440 kilo Ohm.
17

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

Your answer is correct:

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?

Your answer is correct:

It will start/stop the generator sets in response to varying load.
19

Where will you find the instruments for synchronizing the generator?

Your answer is correct:

On the main switchboard.
20

Which control mode is recommended during manoeuvring?

Correct answer:

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

Your Answer:

Optimal, because this mode allows an increased load of the generators during manoeuvring.
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?

Your answer is correct:

Inductive load.
22

Which statement is true?

Correct answer:

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

Your Answer:

The Priority 1 generator will be first IN/first OUT.
23

Which statement is true?

Your answer is correct:

When automatic frequency control is selected, the “follow-up” will parallel shift the speed drop until the generator frequency = nominal frequency.
24

Which statement is true?

Your answer is correct:

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?

Correct answer:

An engine room fan is considered an inductive load.

Your Answer:

An electric heater is primarily a capacitive load.
26

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

Your answer is correct:

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