1, zero-sequence current protection of the protected area is how to divide?
I survived the end of the line of zero-sequence current earthing short circuit through the protection the maximum setting of zero sequence currents; do not protect thefull length of the line, but should not be less than the length of the protected circuit15%~20%; zero-sequence II general protection the total length of the line and extend to the adjacent lines within the scope of paragraph I, and cooperation. Zero-sequence III is I,II of reserve, and in conjunction with adjacent line.
2, computer protection different from the original relay?
Main difference is that the original protection of the input current and voltage signals, and direct comparison between the analog processing, analog and compare withthe devices in a given moment of resistance. And computers can only be numeric orlogical operations. Therefore, first of all require input of analog current, the instantaneous value of voltage transform of discrete digital signals before you can send your computer’s central processing unit, operation required algorithms and proceduresand calculation results were compared with the given number, and tripped to the last judgment.
3, what is the reclosing of accelerating?
When the line fails, protected by setting line switch is off, reclose immediately. If thetransient fault, after the line switch is off, the fault disappears, coincidence is successful, restore power supply line if permanent fault, after the overlap, protect the timeelement is out, making it 0-second trip, this is the fault does not disappear after reclosing action accelerated trip, tripping the fault point.
When the line fails, protected by setting line switch is off, reclose immediately. If thetransient fault, after the line switch is off, the fault disappears, coincidence is successful, restore power supply line if permanent fault, after the overlap, protect the timeelement is out, making it 0-second trip, this is the fault does not disappear after reclosing action accelerated trip, tripping the fault point.
4, error after disconnecting switch should do?
(1) fault isolation switch, the switch just left the static contact arc, then immediatelycloses, it can arc to avoid accidents, if the switch has been opened, the transfer switch are not allowed to close;
(2) when fault isolating switch, even if wrong, even in the arc during closing, no more open, because the load switch three-phase arc can cause a short circuit.
(1) fault isolation switch, the switch just left the static contact arc, then immediatelycloses, it can arc to avoid accidents, if the switch has been opened, the transfer switch are not allowed to close;
(2) when fault isolating switch, even if wrong, even in the arc during closing, no more open, because the load switch three-phase arc can cause a short circuit.
5, what is the r, l, c, parallel resonance?
Resistors, inductors and capacitors in parallel circuits, in the presence of a certain frequency sinusoidal power supply, total Terminal voltage and the current phase occurs, the entire circuit is resistance of special State, this State is called the parallel resonance.
Resistors, inductors and capacitors in parallel circuits, in the presence of a certain frequency sinusoidal power supply, total Terminal voltage and the current phase occurs, the entire circuit is resistance of special State, this State is called the parallel resonance.
6, the starting element of distance protection using negative sequence and zero sequence increment what components a bit?
(1) high sensitivity;
(2) the starting element of the visible surge guard;
(3) in the secondary circuit of voltage disconnection will not malfunction;
(4) symmetrical component appears in regardless of the phase failure, so the starting element can be used for a single relay, so simple.
(1) high sensitivity;
(2) the starting element of the visible surge guard;
(3) in the secondary circuit of voltage disconnection will not malfunction;
(4) symmetrical component appears in regardless of the phase failure, so the starting element can be used for a single relay, so simple.
7, evaluation and subject to what conditions may in protection class of device?
All protection devices for a class of equipment, its technology is in good condition, fully meet the security requirements, and meet the following conditions:
All protection devices for a class of equipment, its technology is in good condition, fully meet the security requirements, and meet the following conditions:
(1) protection, relays, components, auxiliary equipment and defect-free secondary circuit.
(2) the principle, wiring and fixed values are correct, comply with the relevant requirements, ordinances and accident prevention measures demand.
(3) documentation is complete and realistic.
(4) good running condition.
(2) the principle, wiring and fixed values are correct, comply with the relevant requirements, ordinances and accident prevention measures demand.
(3) documentation is complete and realistic.
(4) good running condition.
8, what are the control switch check the project and its contents?
Control switch check includes:
(1) the housing clean and grease-free, intact.
(2) installation should be solid, when not active.
(3) the seal cover seal is good.
(4) the wiring connection should have a firm, not loose, does not rust.
(5) flexible rotation, correct position, good contact.
(6) open the sealed doors, using flashlights to check, should be clean and grease not dry, without burning the contact point. Pressure test of insulating sticks contacts, pressure should be good.
Control switch check includes:
(1) the housing clean and grease-free, intact.
(2) installation should be solid, when not active.
(3) the seal cover seal is good.
(4) the wiring connection should have a firm, not loose, does not rust.
(5) flexible rotation, correct position, good contact.
(6) open the sealed doors, using flashlights to check, should be clean and grease not dry, without burning the contact point. Pressure test of insulating sticks contacts, pressure should be good.
9, transformer differential protection in transformer no-load input private check what?
Differential protection of transformers, in new installations the transformer at ratedvoltage must be done 5 times under no-load test. Before the no-load, should checkthe secondary connection, and make sure that is correct. No-load test in the transformer power supply side and low pressure side, this is because the system impedance and hungry leakage can limit the inrush current of transformers, and power supplysystem impedance is small and generally low voltage winding around the inside, less leakage, is greater in large power and low voltage input inrush current. In the trial,protection devices and should not be, you should increase the operating current of the relay.
Differential protection of transformers, in new installations the transformer at ratedvoltage must be done 5 times under no-load test. Before the no-load, should checkthe secondary connection, and make sure that is correct. No-load test in the transformer power supply side and low pressure side, this is because the system impedance and hungry leakage can limit the inrush current of transformers, and power supplysystem impedance is small and generally low voltage winding around the inside, less leakage, is greater in large power and low voltage input inrush current. In the trial,protection devices and should not be, you should increase the operating current of the relay.
10, in the split second line, what measures should be taken?
Dismantled when the second line, you must record; restored. Shall be recorded in the logbook logs off. The second line changes when there are should be tied on eachthread. Dismantled or the laying of two cables, along the end of the cable and bendand cross symbol tie card.
Dismantled when the second line, you must record; restored. Shall be recorded in the logbook logs off. The second line changes when there are should be tied on eachthread. Dismantled or the laying of two cables, along the end of the cable and bendand cross symbol tie card.
Gas protection measures against accidents in 11, what are the requirements?
(1) will buoy the flapper of gas relay, contact to vertical in order to improve the reliability of gas.
(1) will buoy the flapper of gas relay, contact to vertical in order to improve the reliability of gas.
(2) to prevent the leakage of gas relay short circuit at its ends and cable leads rain-proof measures on the terminals in the terminal box.
(3) gas relay pinout oil line should be used.
(4) the hungry is relay pinout and cables should be connected on terminals in the terminal box cable leads.
12, is a general principle of transformer protection installed?
(1) defence internal short circuit of transformer shell of gas and oil to reduce protection.
(2) defense interphase short circuit of transformer coil and lead-out, large grounding grid side leads to the side of the short and the coil turn to turn short-circuit of longitudinal differential protection or current fast-tripping protection.
(3) defense external interphase short circuit of transformer gas protection and overcurrent protection for longitudinal differential protection reserve (or composite voltage overcurrent protection for startup, or negative phase-sequence current protection).
(4) defense external earthing short circuit in a large grounding grid of zero-sequence current protection.
(5) defense symmetric overload overload protection.
13, the starting element of distance protection what?
(1) short circuit fault, quick-start protection device;
(2) starting surge guard, or paragraph III of the doubles as a measuring element;
(3) paragraph-level switch;
(4) the phase switch;
(5) protection at the transistor, if DC logic fails, blocking whole.
(2) starting surge guard, or paragraph III of the doubles as a measuring element;
(3) paragraph-level switch;
(4) the phase switch;
(5) protection at the transistor, if DC logic fails, blocking whole.
What do 14, 10,000-volt transmission line installed to protect?
(1) short circuit protection: single power supply line is installed with two-stage overcurrent protection, current fast-tripping protection, overcurrent protection. General installation of double power lines with or without direction, current speed and current fast-tripping protection.
(2) ground fault protection: General installation of non-selective insulation monitoring protection, overvoltage protection, zero-sequence directional power protection.
(2) ground fault protection: General installation of non-selective insulation monitoring protection, overvoltage protection, zero-sequence directional power protection.
15, the effect of negative feedback on the performance of the amplifier is what?
(1) reduce the magnification,
(2) increase the magnification of stability,
(3) improved distortion,
(4) broaden the pass band,
(5) to change the input and output impedance of the amplifier.
(2) increase the magnification of stability,
(3) improved distortion,
(4) broaden the pass band,
(5) to change the input and output impedance of the amplifier.
PLC ONE 