Multiple Choice

1, Power system oscillation, the point of voltage and current (A). A, were back and forth of the swing; B, are mutations; C change fast; D, back and forth between the voltage swing.
2, from the time limit for each section protected by the (C) established. A, measurement part; B, the logic part; C, start part; D, the polarization circuit.
3, BZT device on the following statements is wrong is (D). A, automatic device should ensure that action only once; B, should ensure that the power supply or device off before put into standby power or equipment; C, working voltage power supplies or equipment, whether for any reason disappears, the automatic device should be action; D, whether or not the work of disconnecting the power or equipment, or equipment can be put into standby power.
4, reclosing can overlap capacitance (B). A, two; B, one; C, three times; D, view the road conditions.
5, when the line protection in recent back-way, split-phase operation for 220KV circuit breaker tripping the case of single-phase, should be installed (B) protection. A, non-phase operation; B, failure; C, zero sequence current; D, the direction of high frequency.
6, high frequency protection channel is the role of the coupling capacitor (A). A, frequency current to the great resistance to prevent the invasion of high-frequency high-voltage transceiver transmitter; B, on the power frequency current with a small resistance, prevents the invasion of high-frequency high-voltage transceiver transmitter. C, high-frequency current impedance of a large, high-frequency current can not pass.
7, on with the mother of the circuit breaker and busbar section circuit breaker operation after the breaker failure protection requirements should be (B). A, only the circuit breaker or disconnect the mother of the sub-breaker; B, first disconnect the mother of the circuit breaker circuit breaker or section, and then moves to disconnect tripping circuit breakers connected to all power to the same bus slip crowbar; C, disconnect the mother of the circuit breaker or busbar section circuit breaker and all connected switches.
8, the bus switching operation process, the mother of the operation of the power circuit breaker shall be (A). A, opened; B, closed; C, according to the actual situation.
9, the transformer short circuit test, because the applied voltage and short circuit current is the rated short-circuit current, the applied voltage is called the (A). A, short-circuit voltage; B, rated voltage; C, test voltage.
10, high-voltage side of step-down transformer winding three-phase power are generally in the high pressure side with the tap. If the change in the pressure side of the tap position (B). A, change the high and low voltage side voltage; B, change the low side voltage; C, changing the medium and low voltage side of the voltage.
11, when the transformation ratio of the two transformers in parallel operation of different when circulation is generated in the two transformers, making the two transformers no-load output voltage (C). A, increase; B, reduced; C, become larger than the rise, a small drop; D, become smaller rise than the big drop
12, in a small ground system, when the single phase grounding in somewhere, open triangle bus voltage transformer voltage (C). A, the more recent bus voltage failure the higher the pitch; B, the more recent failure Pitch bus voltage lower; C, regardless of distance, basically the voltage as high as
13, aluminum alloy equipment connectors overheating, its color (C). A, gray; B, black; C, was gray; D, was silver white.
14, high frequency protection scope of protection (A). A, the line length; B, the adjacent part; C, the line length and the next part of a line; D, adjacent lines.
15, circuit breaker failure protection in (A) action.
A, when the circuit breaker tripping; B, Protection during the time; C, circuit breakers overlap in the permanent fault; D, loss of pressure when the distance protection.
16, an internal failure of the transformer primary protection is (A) protection.
A, gas; B, differential; C, over-current; D, over-voltage.
17, to protect the current transformers are not completely star connection, in the operation (A) failure.
A, can not reflect all of the ground; B, to reflect the various types of ground; C, reflect only single-phase ground; D, does not reflect the three-phase short circuit.
18, zero sequence current distribution depends on (B).
A, generator is grounded; B, the number of neutral grounding transformer; C, electrical equipment enclosure is grounded; D, the fault current.
19, the main transformer neutral grounding switch is closed after the (A) inputs.
A, the neutral point of zero-sequence overcurrent; B, the gap over current; C, the gap over-voltage; D, the main transformer compound voltage-current protection.
20, from the protection of a scope of protection is (C).
A, half of the protected circuit lines; B, the full length of the protected circuit; C, the protected line length of 80% -85%; D, the protected line length of 20% -50%.
21, from the scope of protection is the protection of Sec (B).
A, the protected line length of 95%; B, and the protected line length of a line extending to the next part; B, not a protection to the circuit from the rest.
22, access to distance protection relay impedance measurement of impedance and (C).
A, has nothing to do with the operation mode; B, short form has nothing to do; C, Relay location proportional to the distance to the fault; D, and the short circuit is proportional to short-circuit capacity.
23, zero-sequence protection setting time-bound action (B).
A, should consider the current system for the protection of small ground movement time; B, a small ground current system does not consider the action on the protection limit; C, should be with the distance, high-frequency protection compatible.
24, the transformer differential protection for phase diagram (hexagon diagram) analysis, the transformer should be (C).
A, load B, power C, with a certain load
25, occurred three phase short circuit, short circuit current contains (A).
A, positive sequence component; B, negative sequence component; C, zero sequence components.
26, SFPSZ transformer cooling method (C).
A. natural cooling; B, wind cooling; C, forced air-cooled oil circulation.
27, the following statement on the transformer is correct (D).
A, 110kV transformer above the transmission stops before the neutral must be grounded. B, the transformer can be had in the normal case load and run accident overload, normal overload overload and accidents can always use. C, differential protection transformer out of gas or brake can try to send again. D, transformer load loss is equal to the most efficient short run loss.
28, there is a no-load running line, the first terminal voltage and terminal voltage are U1 and U2, the following is correct (C).
A, U1> U2; B, U1 = U2; C, U1
29, under any circumstances, frequency of more than 50 ± 0.2Hz duration shall not exceed (B); frequency exceeding 50 ± 0,5 Hz for duration shall not exceed (A).
A, 15min; B, 30 min; C, 45 min; D, 1h.
30, under any circumstances, monitor, control point voltage below the voltage 95%, 105% higher than the specified voltage shall not exceed the duration (D); below the voltage of 90%, 110% higher than the voltage of the continuing requirement shall not exceed (C).
A, 15 min; B, 30 min; C, 1 h; D, 2h.
31, two transformer capacity, short-circuit impedance of the same 30-degree angle when the difference side by side, their circulation for the export of three-phase transformer short-circuit current (1 / 4) times. A, 1 / 2 B, 1 / 3 C, 1 / 4 D, 1 / 532, China's electric power system neutral grounding There are three, namely, (C).
A, direct grounding, grounding via arc suppression coil and grounded by way of a large reactor. B, no grounding, grounding via arc suppression coil and grounded by way of a large reactor. C, direct grounding, no grounding, grounding via arc suppression coil.
33, in the 6kV-10kV, 20kV-60kV small current grounding system, ground current, respectively (A), the need for the installation of arc suppression coil to avoid burning equipment, resulting in intermittent short circuit between phases and over-voltage.
A, is greater than 30A, more than 10A; B, is greater than 10A, more than 30A; C, are greater than 10A
34, busbar current differential protection using voltage blocking device is to prevent (C) .
A, failure occurs outside the bus current differential protection. B, oscillation occurs when the system bus current differential protection. C, the error caused by hitting the export relay bus current differential protection.
35, another sequence current protection only occurred in the system (B) failure to move this protection.
A, phase short circuit fault caused by three-phase arc; B, or non-phase system grounding; C, two-phase asymmetrical short circuit.
36, high-current grounding system, grounding occurred at any point, the zero sequence current through the fault current is equal to (A).
A, 1 / 3 times; B, 2 times; C, 2.5 times; D, 1.5 times.
37, the polarity of the current inter-dried control (C) no effect.
A, distance protection; B, the direction of protection; C, current-speed section protection; D, differential protection.
38, in the event of non-phase running (C) protection is not closed.
A, from a; B, another sequence Sec; C, high-frequency protection.
39, RC series circuit in the DC, the voltage on the resistor R is equal to (A).
A, 0; B, full voltage; C, 2 times the voltage; D, R / (R + XC).
40, power supply voltage higher than the rating of the transformer, the core of the loss will (C).
A, reduced; B, unchanged; C, increases; D, no rule change.
41, Y, d11 wiring line voltage transformer secondary side ahead of a line voltage (B).
A, 30 °; B, 30 °; C, 300 °; D, 60 °.
42, zero sequence current filter and zero sequence current transformer only (C), the only zero sequence current output.
A, three-phase short circuit; B, two-phase short circuit; C, single-phase short circuit; D, three-phase short circuit to ground.
43, when the power system oscillation occurs, (C) malfunction may occur.
A, current differential protection; B, Zero Sequence Current Protection; C, Current Protection; D, non-electricity protection.
44, RLC series circuit the impedance Z = (C) ohms.
A, R + ωL +1 / ωc; B, R + L +1 / C; C, R + jωL + 1 / jωc; D, R + j (ωL + 1/ωc).
45, circuit analysis and the fundamental basis for the computational complexity is (C).
A, Ohm's law; B, Kirchhoff's laws; C, Kirchhoff's laws and Ohm's law; D, node voltage method.
46, the operation of the current transformer, when a current does not exceed 1.2 times the rated value, the current increases, the error (C).
A, unchanged; B, increased; C, did not change significantly; D, decreased.
47, arresters installed substation bus to (C).
A, to prevent the cloud-to-; B, to prevent the counter over-voltage; C, to prevent the lightning wave.
48, occurred when the two-phase short circuit, open circuit current contains (C) components.
A, positive sequence; B, negative sequence; C, positive sequence and negative sequence; D, positive sequence and zero sequence.
49, in order to prevent voltage transformer protection malfunction caused disconnection, distance protection (B).
A, do not take voltage; B, the installation of a broken locking device; C, taking the value of multiple voltage transformer; D, secondary fuse is not installed device.
50, over-current protection can be installed composite voltage lockout (C).
A, to facilitate cooperation on the lower level; B, promoting the conservation of reliability; C, to improve the sensitivity of protection; D, selective.
51, the standard of Shandong power grid frequency is 50 Hz, the frequency deviation of not more than (A) Hz.
A, ± 0.2; B, ± 0.1; C, ± 0.3; D, ± 0.5.
52, double busbar current differential protection, when the fault occurred in the bus coupler circuit breaker between the TA and the mother of the dead zone when you move, this time should be (B).
A, start the remote tripping; B, start the mother of the failure protection. C, start failure protection and remote tripping; D, does not operate.
53, double bus runs during the switching operation there will be two separate switches are closed, and if a parent fails this time, bus protection should be (A).
A, removal of double-bus; B, removal of faulty bus bar; C, start failure protection and remote tripping; D, no action, removal from the remote backup protection fault.
54, current transformer is (A).
A, current source, the resistance as infinite; B, current source, the resistance as zero; C, voltage source, resistance as infinite; D, voltage source, resistance as a zero.
55, rapid removal of the main fault line protection at any point is (C).
A, distance protection; B, zero sequence current protection; C, pilot protection.
56, the main protection or circuit breaker tripping when the fault protection is used to cut (A).
A, backup protection; B, supplementary protection; C, high current joint cutting device.
57, back-impedance protection to prevent the transformer when the voltage is disconnected malfunction must be (C).
A, the installation of voltage disconnect locking device; B, start the installation of the current incremental components; C, while the installation of voltage and current increments break start locking device components.
58, the transformer ratio differential relay brake, set the main rate of braking is (B).
A, to avoid inrush current; B, when the imbalance in external fault current increases, in order to relay the current increased with increasing imbalance in the current action value; C, in order to raise the internal fault protection operation reliability.
59, single-phase reclosing of the line, when a permanent single-phase ground fault occurs, the protection and reclosing the action sequence (B).
A, three-phase tripping do not coincide; B, jumping fault phase selection, delay coincidence single phase, accelerated after the jump phase; C, jumping fault phase selection, instantaneous coincidence of single-phase, accelerated after the jump phase.
60, circuit breaker failure protection (C).
A, a recent backup protection, when the fault protection devices tripping, you can rely on the protection of excision failure; B, a remote backup protection, when faulty components of the circuit breaker tripping, the fault element must rely on their own Starting failure protection action signal to remove the point of failure; C, a near back-up protection, when faulty components of the circuit breaker tripping, you can rely on the protection of isolated point of failure.
61, in large ground current system, the line beginning there were two phase metallic side is shorted to ground, the direction of zero sequence current protection device in the direction of the (B).
A, due to short-circuit phase voltage zero and refuse to move; B, the maximum zero sequence voltage due to feelings and sensitive action; C, because of the zero sequence voltage is zero and refuse to move.
62, Which is not a condition of the transformer operating in parallel (B).
A, variable ratio equal; B, the capacity is equal; C, short-circuit voltage equal; D, winding connection group of the same.
63, neutral grounding via arc suppression coil system, arc suppression coil compensation method should be used (C).
A, due to compensation; B, fully compensated; C, over compensation; D, more than can be.
64, on the same system, including the equipment, most are (A).
A, power system; B, power system; C, power grid; D, electrical equipment.
65, a small ground current system of single phase, the ground point current (A).
A, the system is relatively normal for every 3 times the total capacitive current; B, normal system, the total capacitive current; C, grounding line load current.
66, protection of (A) is the most basic performance requirements of relay protection.
A, reliability; B, selective; C, fast; D, sensitivity.
67, high frequency protection in the role of traps (B).
A, send and receive signals; B, Tong-frequency, high frequency resistance; C, through high-frequency, stop frequency; D, to prevent lightning strikes.
68, due to the long line of capacitive effect and sudden changes in network operation mode caused by a relatively long duration over-voltage is called (A).
A, frequency overvoltage; B, the atmosphere over-voltage; C, operating over-voltage; D, resonance over-voltage.
69, involving more than two units need to meet the operation or after an operation on the grid before the impact can decide the next operation must be used (B).
A, real-time instruction; B, one by one instruction; C, comprehensive instructions.
70, the following wiring for the wiring is no alternative (A).
A, radial; B, ring; C, both ends of the supply network; D, double-trunk style.
71, DC bus voltage can not be too high or too low, the allowable range is usually (C).
A, ± 3%; B, ± 5%; C, ± 10%; D, ± 15%.
72, the so-called bus charging protection means (C).
A, mother and next to the associated circuit breaker with outlet protection backup protection; B, by bus to the bus took charge of a circuit breaker protection; C, use of mother of the circuit breaker to another bus charging protection; < br> 73, harmonic restraint differential protection of transformer, set the speed differential is mainly due to broken components (B).
A, action to improve the speed differential protection; B, in order to prevent failures in the region, the higher short circuit level, due to saturation of current transformer high harmonic generation increased, resulting in differential Element Fails ; C, the double set of protection, mutual backup; D, differential protection of backup protection.
74, latching trip pilot protection is a necessary condition (A). Note: The correct answer is C, Please check back
A, is the direction of component motion in the opposite direction components do not move, did not received a blocking signal; B, is the direction of movement components, components do not move the opposite direction, received lockout signal; C, positive and negative direction components are actions, not received a blocking signal; D, positive and negative directional element is not action, not blocking the signal received.
75, pilot protection signals are blocking the signal, allowing the signal and (A).
A, trip signal B, notice the signal C, signal delay D, the instantaneous signal
76, directly in the neutral grounding system, substation transformer low voltage side of power, if only a single transformer substation operation , to prevent ungrounded system power frequency overvoltage condition. One of the point operation mode should be (A).
A, Grounding; B, not ground running; C, according to the decision to run or not run the way; D, decide to run or not according to the load.
77, transformer substation down bus stop operation or transmission operations should normally be issued (C) operating instructions.
A, immediate; B, one by one; C, integrated; D, according to the dispatcher used to issuing.
78, the transformer is (B) of electric power equipment.
A, produce; B, passed; C, the transfer and production.
79, run the transformer in order to adjust separately, you need to cut off the transformer to the load, this voltage transformer is called (B).
A, investment, stop the transformer adjustment; B, no-load voltage; C, load voltage regulation.
80, is generally believed that oil-immersed transformer winding insulation used in the 80 - 140 ℃ range, the temperature for each additional 6 ℃, doubling the insulation aging rate, known as the transformer (B).
A, the aging criteria; B, 6 ℃ criteria; C, operational criteria.
81, together with the isolation switch can pull the following equipment (C).
A, no-load line; B, no-load transformer; C, power without ground fault, voltage transformer.
82, circuit breaker failure protection and the export share bus protection circuit, the blocking device sensitivity should be (A) the requirements of the entire set.
A, failure protection; B, bus differential protection; C, protection of all components on the bus; D, mother of the protection;
83, autotransformer neutral point should be (A) operation.
A, directly to ground; B, is not grounded; C, by the arc suppression coil grounding; D, by the resistance to ground.
84, tied with the grid generator, the generator should be adjusted to the frequency and voltage to meet the (A), the generator only to the grid.
A, either a stable frequency, voltage deviation on both sides of tie points within 1%; B, either a stable frequency, voltage deviation on both sides of tie points within 5%; C, 50 ± 0.2Hz, tied for points on both sides
85, the system generally according to the longest period of oscillation (C) second consideration.
A, 0.5; B, 1.0; C, 1.5; D, 2.0.
86, the following statements is correct (A).
A, arc suppression coil installed in the transformer or the HV side of the neutral point, the system single ground, only from the arc suppression coil compensation function; B, installed in the transformer neutral point on the arc suppression coil On the one hand the system can compensate for normal capacitive current, it also can improve system stability; C, arc suppression coil is the inductive reactance, so the system during normal operation in the arc suppression coil parts of the system to consume reactive power.
87, transport the same load, improve the transportation system of the voltage level will be (B).
A, improve the load power factor; B, reduce line losses; C, to improve the power waveform.
88, the system frequency is lowered, by (C) the ways in which the frequency increased.
A, increase the power generator, reducing the power factor; B, cut into large current associated equipment; C, increase the generator active efforts to reduce the electricity load.
89, a small current grounding system in a single phase ground fault occurs, the ground phase of the voltage (A).
A, lower; B, unchanged; C, increased.
90, cut line and bus rapid short-circuit fault is to improve the power system (A) the most important means.
A, Transient stability; B, static stability; C, dynamic stability; D, more than not.
91, in the small current grounding system, single-phase ground fault occurs, because (A), it is generally allowed a short run.
A, does not destroy the symmetry of the system line voltage; B, made not a small ground current hazards. C, find the point of failure.
92, power switching operation, should be (C) the instructions of the dispatcher on duty.
A, Geological Survey; B, provincial transfer; C, dispatch jurisdiction.
93, change the bus operation mode of operation, by (C) of the dispatcher on duty ordered the operation.
A, Geological Survey; B, provincial transfer; C, dispatch jurisdiction.
94, under normal circumstances, the control point to monitor the voltage below the voltage of 95% of the duration should not exceed (B) hours.
A, 0.5; B, 1; C, 2.
95, LGJQ-400-type cable to allow continuous current (C) A.
A, 645; B, 745; C, 845; D, 945.
96, for the same capacitor, continuous cast, cut an interval of time (A) above.
A, 5min; B, 10min; C, 15min; D, 20min.
97, the impact of the new transformer to be put into operation 5 times, after the overhaul of the impact of the number of transformers required for the (A).
A, 3 times; B, 2 times; C, 1 second.
98, the power system automatic safety device has low frequency, low pressure splitting devices, high current with cutting equipment, cutting machine unit, and (B) and so on.
A, differential protection; B, low frequency, low-voltage load shedding device; C, failure protection.
99, depending on the frequency characteristics of power system frequency generator and (A).
A, load frequency characteristics; B, the power system voltage characteristics; C, generating the static stability.
100, the minimum technical thermal power output from the (A) decision.
A, boiler technology allows minimum load; B, turbine technology allows minimum load; C, the stable operation of generators.
101, a 110kV line by the step-down transformer power supply to the 10kV distribution system, occurs when the 10kV single phase distribution system, the 110kV line protection. (B).
A, Tripping; B, does not move; C, low-voltage side of transformer protection Tripping.
102, line current transformer overload by 10% or lines not exceeding 15% overload, the provincial transfer restrictions ordered by the electric power area, wind up, the circuit overload no more than (B).
A, 15 min; B, 20 min; C, 30 min.
103, the new production line or the line changes, you must (A).
A, to check the phase, phase sequence; B, do not have to check the phase, phase sequence. C, according to decide.
104, electrical equipment damage, direct economic losses of up to (D) million persons, as a large equipment accident.
A, 100; B, 200; C, 500; D, 1000.
105, following a
A, capital cities and cities with independent national plan for the city less than 80% load; B, provincial capitals and cities with independent national plan for the city by 40% or more of the load; C, power grid collapse.