Main protection contents and differences of transformer
Writer： Hengfeng you electric Time：2023-04-03 views：times
1. Difference between main transformer differential maintenance and gas maintenance
Differential maintenance is the main maintenance of transformer, and gas maintenance is the main maintenance of internal faults of transformer. The scale of differential maintenance is the primary equipment of the differential current transformer on both sides of the transformer. The primary reaction is the phase to phase short circuit of the internal winding of the transformer, the single-phase severe turn to turn short circuit, and the phase to phase short circuit of the outgoing line and the insulating bushing; The scale of gas maintenance is the internal fault of the transformer, which mainly reflects the internal polyphase short circuit, inter turn short circuit, iron core and skin short circuit, iron core heating, oil leakage, right side drop, etc. Differential maintenance can quickly remove the faults within the maintenance scale, analyze that if it is properly debugged, there will be no misoperation, but it is not sensitive to the turn to turn short circuit without serious internal faults of the transformer. Gas maintenance reflects various internal faults of the oil tank, but also reflects the less severe inter turn short circuit and iron core heating problems that cannot be reflected by differential maintenance, and the internal air enters. Therefore, it has high sensitivity and quick action. Its defect is that it can not reflect the external faults of the transformer, poor anti-interference performance and simple misoperation.
2. Treatment of the problem that the disconnector cannot be opened
When the disconnector cannot be opened, if the operating mechanism is frozen, shake it slightly. Now pay attention to each part of the supporting insulator and operating mechanism, so as to find out the place of resistance according to their deformation and displacement. If the resistance to pull-out occurs on the touch device of the knife switch, it should not be forcibly pulled apart; Otherwise, the supporting insulator may be damaged and cause serious accidents. At the moment, the only way is to change the operation method of the equipment.
3. The reason why the disconnector cannot cut off the heavy load current
When breaking a large current, the temperature of the arc is very high, the thermal dissociation and collision are aggravated, and the arc diameter is increased, so the dielectric strength recovery is slow. Because the disconnector has no arc extinguishing equipment, the arc occurs when breaking, and the arc extinguishing capacity of the atmosphere is very poor. Therefore, when the thermal dissociation and collision dissociation are aggravated, the dielectric strength is exploited and simply broken down, If it is broken down, it will form a phase to phase arc short circuit, which can not only damage the disconnector and its nearby equipment, but also pose a great risk to the staff, which will form severe circuit problems. Therefore, the disconnector cannot cut off the heavy load.
4. Phenomenon and treatment method of current transformer disconnection
Common faults of current transformer include:
(1) Overheating
(2) Smell or smoke inside
(3) There is discharge inside, abnormal sound or spark discharge between lead and shell
(4) Main insulation breakdown, resulting in single-phase grounding fault
(5) Short circuit occurs between turns or layers of primary coil and secondary coil
(6) Oil leakage of oil filled current transformer
(7) The secondary circuit is broken
handle:
When the above problems are found, report to the power regulator and cut off the power supply for treatment. If it is found that the secondary circuit connector of the current transformer is heated or disconnected, try to tighten it or short circuit it with a safe thing at the terminal near the current transformer; If it cannot be handled, it shall be reported to the electric dispatcher to stop the current transformer for treatment
5. Problems needing attention when placing equipment room on the device wiring diagram
(1) the spacing size between equipment on the device wiring diagram does not need to be made in proportion. Since the equipment size and device orientation have been determined on the panel placement diagram, the overall size of the equipment and the spacing between them can be arbitrarily expanded or reduced only on the condition that the terminal label is clear
(2) The relative orientation of the equipment shall be consistent with the orientation of the practical device. Since the device wiring diagram is generally a back view, the orientation of the equipment is opposite to that on the panel placement diagram
(3) The shape of the equipment shall be consistent with the physical object as far as possible. Except that the internal wiring diagram can not be drawn for simple equipment such as ammeter and voltmeter, the internal wiring diagram of other complex equipment such as relay shall be drawn
6. Components and functions of relay maintenance equipment
The function of the measurement part is to measure the operation status of the maintained components and respond quickly and accurately to the corresponding changes of one or several physical quantities. The comparison part is also called the logic part. Its function is to compare the physical quantity measured by the measurement part with a set value, so as to determine whether the maintained element has failed, so as to determine whether the maintenance equipment should act. The function of the execution part is to send out signal pulses to trip and act the circuit breaker according to the action instructions of the comparison part, so as to complete the action mission of the maintenance equipment.
