Technical questions about diesel generator sets

NOUN interpretation:

1. Loss of magnetism: loss of excitation is the interruption of excitation current caused by some faults in the excitation circuit during the operation of the generator.

2. Zero sequence current: when any single or two grounding fault occurs in any point of the power system, zero sequence current will be generated in the system. At this point, the grounding fault point will be a function of the zero sequence voltage, voltage will generate zero current, zero sequence current is from the fault point to the earth by the electrical equipment grounding fault point for the loop to return after a unique reflection of earth fault current.

3. High frequency current: high frequency signal current in high frequency protection circuit. The current and power current compared to the name, the current per minutes change 50 times, and the high frequency current per second changes more than 35KHZ, now high frequency system used in general is 35 ~ 500KHZ.

4, breakdown voltage: insulation materials under the influence of voltage, time out of a certain critical value, the dielectric suddenly lose insulation ability, and the discharge phenomenon is called breakdown, this critical value is called breakdown voltage.

5. Increasing current: auxiliary current is an additional current that affects the correct operation of distance protection. Because in many cases, there are other branches of current protection installation at the contact point of failure between these power will supply additional short-circuit current, which is greater than the current into the protection device of the current through the fault line. This current and called boost current.

6. Capacitive voltage transformer: the voltage transformer is called voltage transformer with capacitive partial pressure principle.

7 、 high frequency processing equipment: high frequency wave blocking device, coupling capacitor, link filter and high frequency cable, etc., are collectively referred to as high frequency processing equipment of high voltage line.

8. Distribution equipment: a type of electrical building which is constructed by linking all kinds of primary electrical equipment according to certain requirements and used to represent the production, transportation and distribution of electric energy, thus becoming a power distribution unit.

Questions and answers:

1, what is the difference between computer constitution protection and original relay protection?

The main difference is that the original protection input is current and voltage signals, which are directly processed between analog signals, so that the analog torque is compared with the given resistance torque in the device. A computer can only do digital or logical operations. Therefore, the first requirement of the analog input current and voltage instantaneous value transform discrete digital quantity, and then sent to the central processor of the computer operation in accordance with the provisions of the algorithm and the program, and the calculation results were compared with any given number, and finally make judgment whether the trip.

2, how is the protection scope of each section of the zero sequence current protection divided?

Zero sequence current I segment at the end of the line from the ground fault protection through maximum zero sequence current setting; full length cannot line protection, but should not be less than the protected line length of 15% ~ 20%; general II zero sequence protection line length, and extends to the adjacent line I range, and to cooperate with the. The zero sequence III segment is the backup section of the I and II segments and is coordinated with adjacent lines.

3. What is the post acceleration of reclosing?

When the line is out of order, the protection shall be set according to the setting value, the line switch will be disconnected, and the reclosing will be operated immediately. If the transient fault, the circuit switched off, the fault disappears, coincidence of success, to restore the power supply line; if the permanent fault reclosing time, protection element is out, make it for 0 seconds trip, this is the reclosing after the fault does not disappear accelerate tripping tripping fault point.

4. What should be done after handling the disconnector?

(1) no isolation switch, knife gate just left the static contact occurs arc, then immediately closed, you can avoid accidents, Petersen, if the knife has been opened, it will not pull the wrong knife close again; (2) the wrong pull isolation switch, even if he is wrong, or even when closing the arc, and no more open, because the load switch will cause the three-phase short circuit arc.

5, what is R, L, C parallel resonance?

A circuit in which the resistance, inductance and capacitance are connected in parallel. Under the influence of sinusoidal power supply with certain frequency, the voltage at the circuit end and the total current are in phase, and the whole circuit is in a state of resistance. This state is called shunt resonance.

6. What are the main features of emitter follower?

The input resistance is large, the output resistance is small, and the voltage amplification factor is approximately equal to 1, but less than 1, the input voltage is the same as the output voltage.

7. What are the conditions for the protection device and can be used to evaluate a class of equipment?

All kind of equipment protection device, its technical condition is good, the performance fully meet the requirements of the safe operation of the system, and meet the following conditions: (1) protection screen, relays, components, auxiliary equipment and the two loop free of defects. (2) the principle of the device, the wiring and the correct value, comply with the provisions of the relevant regulations, regulations and anti accident measures. (3) the drawings are complete and conform to the actual situation. (4) good running condition.

8. What are the inspection items and contents of the control switch?

To check the contents of the control switch are: (1) the shell clean and free of grease, intact. (2) the installation should be firm and inactive during operation. (3) the sealing cap is well sealed. (4) each thread should be firmly connected, not loose and not corroded. (5) flexible rotation, correct position and good contact. (6) open the sealed lid, and inspect with a flashlight. The inside should be clean, the grease is not dry, and the contact point is not burnt. Test the contact piece with insulating rod and the pressure should be good.

9, transformer differential protection in the transformer no-load input, private inspection what content?

Transformer differential protection, the new transformer must be installed at the rated voltage to do 5