Switchgear consists of incoming, metering, PT, outgoing and so on. The cabinet is equipped with primary and secondary components, which must be matched at the time of purchase, so it is called "complete set".
2, China's power voltage how many levels, and say the role of grading.
Divided into 500KV, 220KV, 110KV, 35KV, 10KV, 380V, 220V and other levels.
As the level of voltage is related to line loss, the higher the voltage, the lower the line loss. In this way, the farther the distance to transport electricity, the higher the voltage level to be transported.
3. Why do we need to unload voltage (10KV level)? What is the safe way to unload the voltage?
When a power outage occurs, the voltage must be removed to prevent the capacitor from having a residual charge that could injure people.
The method of removing voltage safely: When you open the cabinet door or screen board, do not touch the busbar directly with your hands. First 10KV test pen to check whether there is electricity, and then find a wire, one end of the ground, one end connected to the front of the test pen, with the front of the test pen to contact the bus discharge, complete the maintenance before, to ensure personal safety. Remember this.
4, 10KV test voltage should be how much? What is the difference between domestic and international standards?
Domestic: 42,000 volts cabinet, 48,000 volts break;
International: 36,000 volts
5, how to understand the switchgear model in the meaning of the letters KYN?
K-Metal-enclosed armored type
Y-Shift-open type
N-Indoor
6. What is the function of the pressure relief channel?
If there is an explosion in the cabinet, it will generate a strong gas wave. If there is a pressure relief channel on the top of the cabinet, the air wave can be discharged from the top, without affecting the normal operation of other parts; if there is no pressure relief channel, the air wave will be rushed to the weakest place.
7, switchgear should be assembled with those main primary components?
Circuit breaker, contact block, arrester, zero sequence transformer, current transformer (CT), voltage transformer (PT), high voltage fuses and so on.
8, ring network switchgear role? By what to protect the transformer?
The role is to take the load switching, he relies on high-voltage fuses to protect the transformer.
9, air insulation distance of the national standard is how much?
Phase-to-ground air distance, 10KV requires 125mm.
10, what is called insulation creepage distance?
High-voltage energized side to the ground, along the insulating parts of the exterior of the creepage of the conduction distance is called insulating parts creepage distance. 10KV requires 235mm.
11, with what method to check whether the vacuum switch vacuum?
Checking with voltage test. The breakout is detected with 48,000 volts.
12, isolation plug, isolation switch has what function, used for which cabinet type?
Isolation plug, used for trolley cabinets; isolation switch for fixed cabinets. Their role are not load switching, convenient maintenance.
13, high-voltage cabinet current roughly divided into several levels? Load switch belongs to which level?
Large, medium and small, that is: 3150A, 1250A, 630A three levels. Load switch is 630A level.
14, high-voltage fuse role?
For the protection of transformers, PT is a small transformer class.
15, what is the role of the charged monitor?
The role of the indicator, showing whether the cabinet has high voltage.
16, what is the role of the program lock? Installed in what place?
Cabinet and cabinet operation sequence according to the specified program chain, play a role in preventing misoperation.
17, what is the role of the grounding switch?
The grounding switch is installed at the end of the outlet line to prevent backward supply of high-voltage electricity during maintenance and ensure personal safety.
18, what is the role of the valve?
When the handcart is pulled away from the cabinet, it prevents people or metal from touching the static contacts with high voltage.
19, busbar why the sleeve rubber?
To play an insulating role, can reduce the air insulation distance, to prevent small animals into the cabinet caused by short-circuit accidents.
20, what is the role of lightning arrester? Why each group of cabinets have at least one lightning arrester?
Surge arrester designed according to the voltage level, can not be installed wrong. Some also according to the use of different designs and different designs. Such as: power plant output of electricity, there are lines running, there are capacitors.
Surge arrester is mainly when a section of the line produces excessive voltage, it can be absorbed in order to achieve the purpose of safe operation of the line. For example: the inlet cabinet has a set of lightning arrester, can protect the cabinet line safety; and external power supply in the cabinet, has been equipped with a lightning arrester, so if the external power supply produces high voltage, due to the lightning arrester for protection, into the cabinet will be safer; outgoing cabinet with a lightning arrester at the lower end of the cabinet, is mainly to consider the vacuum circuit breaker will be generated when the phenomenon of over-voltage, so it is necessary to install a lightning arrester instead of the over-voltage absorber.
21, how to distinguish between phase color and phase arrangement.
22, say the role of current transformer and zero sequence transformer.
Current transformers play a role in metering and protection;
zero sequence transformers play a role in protection.
23, current transformer can be returned to assembly? Why?
Normal flow L1 → L2, if L2 → L1, the secondary line design needs to be modified.
24, VE cabinet and ring network cabinet what is the difference?
VE cabinet (manual type) with circuit breaker breakers to protect the transformer 0.2 seconds
Ring network cabinet (fixed type) with high-voltage fuses to protect the transformer 0.02 seconds
25, what is the role of the wet controller?
The humidity is detected through the induction probe, and if it exceeds the normal humidity, it is regulated through the heat generated by the heating plate. There are two ways of operation: automatic and manual.
26, a program map plays a role?
Representation of the main circuit of the original and the direction of the road assembled
27, PT and CT called on behalf of what?
PT-voltage transformer, CT-current transformer
28, AC and DC called what?
AC - alternating current, DC - direct current
29, circuit breaker has how many operating mechanism?
Manual, automatic power sharing, magnetic, spring, contactor with magnetic suction. Such as: low-voltage air switch with manual
High-voltage vacuum switch with CD10 or CD17 (electromagnetic mechanism), with CT8 or CT19 (spring mechanism)
30, the role of the empty switchgear is what it relies on what to protect the transformer?
The role of the vacuum arc extinguishing, can be loaded with switching, for the transmission of electricity, by the current transformer and instrumentation to cut off the current to protect the transformer. Can also install other components for other purposes.
31, what is the role of vacuum circuit breaker?
Capable of load switching, with vacuum arc extinguishing.
32, vacuum switch trip should be how much?
Travel: 11 ± 1 spring compression: 4 ± 1 VE: 8 ± 0.5
33, the classification of circuit breakers:
(1) Vacuum circuit breaker: the use of vacuum (vacuum degree of 100,000 Hg or less) as an arc-extinguishing medium and the main insulation medium. Arc extinguishing movable and static contacts are sealed in the vacuum interrupter room. Mainly 10VK. 35KV voltage level.
(2) sulfur hexafluoride circuit breaker: came out later. Only in the early seventies was widely used, is now an advanced power system equipment, SF6 gas as the arc extinguishing medium. Cutting capacity is about 10 times higher than the general circuit breaker. Arc voltage is low. Arc burning time is short contact burnout less, can be operated frequently. Disadvantages SF6 is more expensive. Need to recover the device, the structure is more complex. Our country has manufactured attendance 220KV to SF6 as the main body of the fully enclosed combination of appliances. Put the circuit breaker, disconnecting switch. Transformer, arrester. Busbar and other substation equipment all installed in the delivery of SF6 gas sealed container greatly reduces the substation space. It is the main direction of the development of ultra-high voltage electrical appliances. Foreign countries have been widely used.
(3) circuit breaker: compressed air as the arc extinguishing medium. In the ultra-high voltage is currently the main producer. My domestic 380KV. 765KV has been produced abroad.
(4) self-produced circuit breaker: the use of fixed medium by the arc decomposition into gas for blowing the arc so that the arc is extinguished. Low voltage and small current. Applicable to agricultural use of electronic statistics.
(5) magnetic blowing circuit breaker: the use of magnetic fields to blow the arc into the arc extinguishing grid.
34, power transformer
Transformer is a transformer voltage (current) of electrical equipment. It can not transform power.
Basic structure: mainly by a closed core and wound on the core of two turns of different and mutually insulated coils (i.e., windings), in order to reduce eddy currents and hysteresis losses, the core is coated with insulating varnish, the thickness of 0.35-0.5mm good magnetic conductivity of the silicon steel sheet stacked, which consists of a transformer in the closed magnetic circuit of the primary coil is called the thick coil primary side, the secondary coil is called the payment coil type Pay side, with three single-phase transformers connected to the three-phase transformer group, is a three-phase transformer.
35, current transformer
Basic structure: the current transformer is a when used to expand the range of the converter.
Basic structure and ordinary voltage devices, also by the core and wound on the core of the original pay coil, when used, the main primary side of the load in series with the measured circuit, the pay side of the series 5A ammeter and protection relay current coil due to the primary side of the coarse conductor, the number of turns is only a turn or a few turns, but it is a small cathode, the voltage is very low, the series of the circuit to be measured and therefore does not change the complementary measurement of current, the pay side conductor is very thin, the turn is only one turn or several turns, solid, it is small, low voltage, the series is therefore not change the current, the current transformer. Pay side wire is very thin, many turns, but its induced potential is not high (only a few volts) pay side ammeter and relay coil resistance is very small, work, pay side can be regarded as a short-circuit state, according to the principle of operation of the transformer: electric charging inductor primary current ratio should be inversely proportional to the number of turns: L1/L2 = W2/W1 or L1 = W2/W1L2.W2/W1=K2 variable ratio.
36, voltage transformer
Basic structure: is to expand the voltage range of the special transformer, the basic structure and the same as ordinary transformers. Therefore, the voltage transformer original edge and pay voltage relationship U1/U2 = W1/W2.
37, lightning arrester
Basic principle: when the overvoltage is transmitted. Internal and external gap S1, S2 at the same time breakdown. Powerful lightning current flows through the grounding device into the earth to limit the magnitude of the overvoltage.
One of the largest lightning accidents in China: 1989.8.12 Shandong Huangdao oil depot fire. 19 people died, 78 people were injured. 3. 60,000 tons of crude oil by the fire around. Direct losses amounted to hundreds of millions of yuan.
38, high-voltage insulators
High-voltage insulators role: used to support and fix the busbar and the charged conductor, and make the charged conductor between or between the conductor and the earth, there is enough distance and insulation; insulators insulated by the shape of the surface to obtain.
Insulators of different voltage levels. In addition to having different effective height. Its surface condition is also different. Its surface is made into a high and low concave skirt. To increase its surface length.
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