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Inspection method and maintenance procedure of transformer

Writer： Hengfeng you electric Time：2023-04-07 views：times

1、 Inspection method of transformer fault

The causes of transformer failure are sometimes complex. In order to check and analyze the causes smoothly and correctly, the following conditions should be understood in detail in advance:

Operation condition of transformer, such as load condition, overload condition and type of front load; Climate and environmental conditions before and when the fault occurs, such as whether it has been struck by lightning, whether it has been attacked by rain and snow, etc; Temperature rise and

voltage condition of transformer; The nature of relay maintenance action, and find out which action; If changeThe pressure regulator has operation records and should be checked; Check the technical data of the transformer and understand the quality status of the last maintenance; Other external

factors, such as whether there are traces of small animal activities.

Troubleshooting methods:

Intuitive method

Transformers with a capacity of more than 560kv are generally equipped with maintenance devices, such as gas relay, differential maintenance relay and overcurrent maintenance device. When there is a problem with the transformer, the corresponding maintenance device will act, and the gas

relay can accurately reflect the problem of the transformer. If gas relay If there is a signal during the operation of the upper pontoon, it indicates that the transformer accident is relatively light. If the lower pontoon acts, it indicates that a serious accident has occurred in the transformer; Under

particularly serious conditions, when the gas relay acts together, the explosion-proof tube also flushes out gas and oil.

Disassembly inspection

Disassembling the transformer for inspection is a way to judge the nature of the problem and find out the problem part. If the problem occurs in the core or coil, it must be checked for collapse.

If the solid insulation breaks down, there is generally carbon slag accumulation or burnt odor. Therefore, all places with special odor should be carefully smelled and inspected (sometimes the insulation should be stripped for inspection). In addition, check the color and aging degree of the coil from

time to time. According to experience, the insulation aging degree is generally divided into four levels:

Transformer insulation aging classification

Level	Insulation State	Explain
First Stage	Good insulation elasticity, fresh and uniform color	Good insulation
Second Stage	The insulation is slightly hard, but the hand does not deform on time, does not crack or fall off, and the color is slightly dark	Still usable
Third Level	The insulation is brittle, the color is dark, there are slight cracks in the hand on time, and the deformation is not too large	If the insulation is unreliable, replace the coil as appropriate
Fourth Level	The insulation has been carbonized and brittle, and it will fall off or crack when pressed by hand	out of commission

2、 Transformer technical maintenance procedure

Transformers are usually installed in substations. According to different operation and maintenance organizations, the substation can be divided into two types: those with regular duty personnel and those without regular duty personnel. In the substation without regular duty, the designated spot

inspection or maintenance personnel usually maintain the transformer. In terms of operation and inspection of various works of the transformer,The above-mentioned operators have the same rights and responsibilities as the electrician on duty.

The electrician on duty shall check the interval of power transformer and the process content of technical maintenance:

Check the interval of power transformer and the process of technical maintenance

Interval	Contents of technical maintenance procedures	Explain
Power on inspection: 1. For the substation with regular personnel on duty, once every day and night 2. The substation without regular personnel on duty shall not be less than once a day, and the inspection of transformer room shall not be less than once every half a year Unscheduled inspections are carried out in the following cases: 1) When the outdoor temperature changes dramatically 2) Each time the transformer is disconnected under the action of gas relay protection device or differential relay protection device Inspection period of transformer oil in operation: 1) The transformer with temperature difference heat dissipation filter shall not be less than once every three years 2) No temperature difference cooling filter, once a year 3) After overhaul	Carry out the following inspections: 1) Check the thermometer reading 2) Check the shell state of the transformer, whether the transformer leaks oil, whether there is oil in the oil filled bushing, and whether the oil level in the conservator is consistent with the temperature mark 3) Check the condition of insulating sleeve (insulator), oil cooling device, oil collecting device, bus and cable. Whether there is heat at the contact line 4) Check whether the breakdown fuse and signal device are intact 5) Check the condition of the grounding line in the transformer room	The branch line voltage is allowed to continuously exceed 5%, or when the load is 25% of the rated load or the rated load time of day and night is less than 6 hours, the branch line voltage is allowed to continuously exceed 10%. Under the condition that the solidification temperature of transformer oil is not lower than - 40 ℃, the natural oil-cooled transformer can operate at full load

In the substation with regular duty personnel, at least two people shall be on duty in each shift. The foreman on duty shall be responsible for the correct maintenance and safe operation of all electrical equipment in the substation during his duty time.

Shift handover system of substation personnel on duty

Notes for successors

Precautions for shift handover personnel

The successor accepts the duty task of the previous shift, and at the end of the shift, hand over the shift to the successor of the next shift according to the instruction chart. After taking over the shift, read all the records on the duty Notepad, accept the equipment, tools, room keys, duty notepad and statements, report to the superior person on duty that he has entered the duty post and report the defects found after taking over the shift

The shift handover person shall introduce the operation and working system of main electrical equipment, the change of power supply system and operating system, the name of electrical equipment stopped operation and transferred to repair and personnel transfer to the successor

Note: the precautions for shift handover shall be specified in the duty Notepad. Both parties of shift handover shall sign on this Notepad.

Responsibilities of personnel on duty

Normal time

In case of accident

No matter whether the electrical equipment is in standby or working state, the person on duty shall not leave the post without permission before handing it over to the next shift. Under special circumstances, with the permission of the person in charge of the substation, others can leave the duty post when they are on duty.

During operation switching or equipment startup or shutdown, shift handover is prohibited. When the equipment is in fault state, the shift can be handed over as an exception after obtaining the permission of the person in charge of the line and substation

It is forbidden to shift when the accident is being eliminated. When an accident occurs, the person on duty shall immediately notify the person in charge of the substation, and before his arrival, independent measures must be taken to restore the normal operation of electrical equipment

In case of no delay (fire, natural disaster and personal accident), the person on duty shall take independent measures to eliminate the accident, but shall immediately report to the superior leadership after the accident

The above information is provided by Qingdao hengfengyou Electrical Engineering Co., Ltd. for more cooperation intentions, please contact: hfy@hengfengyou.com

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