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If it is judged transformer core fault
1. Core normally need a little pick Reason
Transformer normal operation, charged winding between the reservoir and keep the electric field, while the core and other metal components in the electric field. Capacitance uneven distribution of field intensity is different, the core can not * take charge and discharge phenomenon will produce, undermine the solid insulation and oil dielectric strength, the core must be a little reliable connection.
Core made of silicon steel sheets, in order to reduce eddy currents, there is a certain insulation resistance between chip (typically only a few ohms to tens of ohms), inter-chip capacitance is great, alternating electric field can be considered as paths in the core just a little access to the entire stack of laminations potential holding potential.
When the core or metal structures subject to two or more points (multi-point) is connected, then the contact will result in a closed loop between its key chain portion flux induced electromotive force, and the formation of a loop, resulting in local overheating , burning core.
Transformer core access point, is available * correctly connected. That is the core must be connected, and it must be a little connection.
Core failure is mainly caused by two reasons, one is bad construction process caused by short circuit, the second is caused by external factors annex and multi-point connection.
2. The multi-core connection type
(1) After completion of the installation of transformers, not to transport the fuel tank cap positioning pin upside down or removed, the multi-point connection.
(2) core clamps limbs board stem from too close, tilt core laminations for some reason, the touch to clip leg plate, forming a multi-point connection.
(3) iron yoke screw bushing is too long, and yoke laminations collide to form a new contacts.
(4) under the iron clamps pad between foot and yoke pressboard loss or damage, so that the yoke of the feet caused by contact laminations collide.
(5) has a submersible pump means and medium-sized transformers, submersible pump bearing wear, metal powder into the tank, sedimentation tank bottom, electromagnetic force formed under the bridge, under the yoke of the feet or bottom is turned on, forming a multi-point connection.
(6) immersed transformer tank cover thermometer seat too long, and the clip or yoke, next to the column edge collide to form new contacts.
(7) The oil-immersed transformer tank fell into the metallic foreign body, foreign body such metals makes the core laminations and structure through the cabinet, formed then.
(8) under the clamps and stepped between the wooden yoke pad damp or dirty surfaces, with more sludge to the insulation resistance value is reduced to zero, constitute a multi-point connection.
3. anomaly occurs when multiple access points
(1) generating eddy currents in the iron core, iron loss increases, local overheating of the core.
(2) multi-point connection is serious, and untreated for a long time, will lead to continuous operation of transformer oil and winding too hot, so the gradual aging of oil-paper insulation. Will cause the core laminations two insulating layers aging and loss, overheating will cause greater core, the core will be burned.
(3) multi-point connection for a long time, so immersed transformer oil degradation and produce a combustible gas, the gas relay.
(4) because the body of the core overheated pads and clamps carbonized wood.
(5) multi-point connection makes wiring severe blows, the transformer loss of the normal one o'clock then, the consequences could be disastrous.
(6) multi-point contact can also cause discharge phenomenon.
4. Multi-point pick fault detection
Core multi-point connection failure determination method is usually detected in two ways:
(1) Gas chromatography analysis. Gas chromatographic analysis such as methane and higher olefin component content, and carbon monoxide, and carbon dioxide gas content and little change compared to the past, or the content of normal, then the core overheating, the core may be overheating due to multi-point connection.
Chromatographic analysis When acetylene gas, indicating the core has been intermittent multi-point connection.
(2) whether the current measurement wiring. Connection of the transformer core outer casing can escorts line clamp meter measuring whether there is current on the lead. When the transformer core correctly connected, because there is no current loop is formed. The terminal current is very small, as milliamps (typically less than 0.3A). When save multi-point connection, the core of the main magnetic flux around the turn deposit the equivalent of a short circuit within the circulation flow through the turns, its value determines the point of failure and the relative positions in normal contacts, ie shorted turn in the number of enclosed flux. Generally up to tens of amps. Have escorts line using the measured current, very accurate determination of the presence or absence of multi-core connection failure.
5. Multi-point connection troubleshooting
(1) Transformers temporary exclusion method can not be outage:
① outer lead wire, the fault current is large, you can temporarily turn lines run. But the need to strengthen surveillance, after the disappearance of the iron core fault appears floating potential.
② multi-point connection fault belongs to unstable angina, can work wired in series a slide resistance, so current limiting 1A or less. Slide resistance option is to open the terminal will work properly measured voltage divided by the line current.
③ use chromatographic analysis to monitor trouble spots gas production rate.
④ After measurement to find the exact point of failure, can not handle, you can tab to move to the core to work the same location of the fault, a more substantial reduction in circulation.
(2) overhaul measure.
Monitoring found that transformer deposit followed by multi-point failure, transformer outage, outage should be timely, complete elimination of multi-point connection failures after exiting. The troubleshooting methods, multi-point connection type and reason, should take appropriate measures to overhaul. But there are some cases, a power outage can not find the point of failure after hanging core, can find contacts exact scene the following methods may be used.
① DC law. The core and clamps connecting piece opens, on both sides of the yoke pass into silicon 6V DC, then DC voltmeter successively measured voltage between silicon levels, when the voltage is zero table indicates the reverse may be considered where a malfunction contact.
② AC method. Low-voltage winding of the transformer is connected to AC voltage 220 ~ 380V, this time in the core there is flux deposit. When connected to multiple points failure, with milliamp meter to measure currents occur (core and clamps connecting pieces should be open). Along with a milliammeter yoke levels measured by point, when the milliammeter current is zero, then where is the fault.
Transformer normal operation, charged winding between the reservoir and keep the electric field, while the core and other metal components in the electric field. Capacitance uneven distribution of field intensity is different, the core can not * take charge and discharge phenomenon will produce, undermine the solid insulation and oil dielectric strength, the core must be a little reliable connection.
Core made of silicon steel sheets, in order to reduce eddy currents, there is a certain insulation resistance between chip (typically only a few ohms to tens of ohms), inter-chip capacitance is great, alternating electric field can be considered as paths in the core just a little access to the entire stack of laminations potential holding potential.
When the core or metal structures subject to two or more points (multi-point) is connected, then the contact will result in a closed loop between its key chain portion flux induced electromotive force, and the formation of a loop, resulting in local overheating , burning core.
Transformer core access point, is available * correctly connected. That is the core must be connected, and it must be a little connection.
Core failure is mainly caused by two reasons, one is bad construction process caused by short circuit, the second is caused by external factors annex and multi-point connection.
2. The multi-core connection type
(1) After completion of the installation of transformers, not to transport the fuel tank cap positioning pin upside down or removed, the multi-point connection.
(2) core clamps limbs board stem from too close, tilt core laminations for some reason, the touch to clip leg plate, forming a multi-point connection.
(3) iron yoke screw bushing is too long, and yoke laminations collide to form a new contacts.
(4) under the iron clamps pad between foot and yoke pressboard loss or damage, so that the yoke of the feet caused by contact laminations collide.
(5) has a submersible pump means and medium-sized transformers, submersible pump bearing wear, metal powder into the tank, sedimentation tank bottom, electromagnetic force formed under the bridge, under the yoke of the feet or bottom is turned on, forming a multi-point connection.
(6) immersed transformer tank cover thermometer seat too long, and the clip or yoke, next to the column edge collide to form new contacts.
(7) The oil-immersed transformer tank fell into the metallic foreign body, foreign body such metals makes the core laminations and structure through the cabinet, formed then.
(8) under the clamps and stepped between the wooden yoke pad damp or dirty surfaces, with more sludge to the insulation resistance value is reduced to zero, constitute a multi-point connection.
3. anomaly occurs when multiple access points
(1) generating eddy currents in the iron core, iron loss increases, local overheating of the core.
(2) multi-point connection is serious, and untreated for a long time, will lead to continuous operation of transformer oil and winding too hot, so the gradual aging of oil-paper insulation. Will cause the core laminations two insulating layers aging and loss, overheating will cause greater core, the core will be burned.
(3) multi-point connection for a long time, so immersed transformer oil degradation and produce a combustible gas, the gas relay.
(4) because the body of the core overheated pads and clamps carbonized wood.
(5) multi-point connection makes wiring severe blows, the transformer loss of the normal one o'clock then, the consequences could be disastrous.
(6) multi-point contact can also cause discharge phenomenon.
4. Multi-point pick fault detection
Core multi-point connection failure determination method is usually detected in two ways:
(1) Gas chromatography analysis. Gas chromatographic analysis such as methane and higher olefin component content, and carbon monoxide, and carbon dioxide gas content and little change compared to the past, or the content of normal, then the core overheating, the core may be overheating due to multi-point connection.
Chromatographic analysis When acetylene gas, indicating the core has been intermittent multi-point connection.
(2) whether the current measurement wiring. Connection of the transformer core outer casing can escorts line clamp meter measuring whether there is current on the lead. When the transformer core correctly connected, because there is no current loop is formed. The terminal current is very small, as milliamps (typically less than 0.3A). When save multi-point connection, the core of the main magnetic flux around the turn deposit the equivalent of a short circuit within the circulation flow through the turns, its value determines the point of failure and the relative positions in normal contacts, ie shorted turn in the number of enclosed flux. Generally up to tens of amps. Have escorts line using the measured current, very accurate determination of the presence or absence of multi-core connection failure.
5. Multi-point connection troubleshooting
(1) Transformers temporary exclusion method can not be outage:
① outer lead wire, the fault current is large, you can temporarily turn lines run. But the need to strengthen surveillance, after the disappearance of the iron core fault appears floating potential.
② multi-point connection fault belongs to unstable angina, can work wired in series a slide resistance, so current limiting 1A or less. Slide resistance option is to open the terminal will work properly measured voltage divided by the line current.
③ use chromatographic analysis to monitor trouble spots gas production rate.
④ After measurement to find the exact point of failure, can not handle, you can tab to move to the core to work the same location of the fault, a more substantial reduction in circulation.
(2) overhaul measure.
Monitoring found that transformer deposit followed by multi-point failure, transformer outage, outage should be timely, complete elimination of multi-point connection failures after exiting. The troubleshooting methods, multi-point connection type and reason, should take appropriate measures to overhaul. But there are some cases, a power outage can not find the point of failure after hanging core, can find contacts exact scene the following methods may be used.
① DC law. The core and clamps connecting piece opens, on both sides of the yoke pass into silicon 6V DC, then DC voltmeter successively measured voltage between silicon levels, when the voltage is zero table indicates the reverse may be considered where a malfunction contact.
② AC method. Low-voltage winding of the transformer is connected to AC voltage 220 ~ 380V, this time in the core there is flux deposit. When connected to multiple points failure, with milliamp meter to measure currents occur (core and clamps connecting pieces should be open). Along with a milliammeter yoke levels measured by point, when the milliammeter current is zero, then where is the fault.