Transformer core failure and exclusion:
Transformer windings and core is the transmission and transformation of the main components of electromagnetic energy. Ensuring that they can be run is a matter of concern. Statistics show that the failure caused by core problems, accounting for the total transformer accident in the third. The manufacturing sector on the core of the transformer core has attracted attention, and the core can be * grounded, core ground monitoring, and to ensure that one point of grounding have been technical improvements. The operation department also put the detection and found that the core failure to a considerable height. However, the transformer core failure is still occurring frequently, the main reason is due to multi-core ground and core grounding caused by poor. Now two kinds of fault conditions to determine and deal with an approach to make an introduction.
1 core normal need a little grounding reasons
During normal operation of the transformer, there is an electric field between the charged windings and the tank, while the core and other metallic components are in the electric field. As the capacitance distribution, field strength varies, if the core is not * ground, will produce charge and discharge phenomena, destruction of solid insulation and oil dielectric strength, so the core must have a little * ground.
Core composed of silicon steel sheet, in order to reduce the eddy current, the chip has a certain insulation resistance (usually only a few ohms to tens of ohms), due to great inter-chip capacitance in the alternating electric field can be seen as access, which core In only a little ground can be laminated to the core laminations potential clamped to ground potential.
When the core or metal components such as two or more than two points (multi-point) grounding, the ground will cause a closed loop, the key chain part of the magnetic flux, induced electromotive force, and the formation of loops, resulting in local Overheating, and even burned iron core.
Transformer core only one point ground, is the normal * ground. The core must be grounded and must be grounded.
Core failure is mainly caused by two reasons: First, the construction process caused by poor short circuit, the second is due to accessories and external factors caused by multi-point grounding.
2 core multi-point grounding type
(1) after the completion of the installation of the transformer, the fuel tank is not on top of the transport pins flip over or removed, constitute a multi-point grounding.
(2) as the core clip pieces from the core column too close, the core lamination for some reason after the tilt, touching the clamp pieces, the formation of multi-point grounding.
(3) iron yoke screw bushing is too long, and iron yoke lamination of touch, constitute a new grounding point.
(4) iron core under the clamp feet and iron yoke between the insulation board off or damaged, so that the foot yoke at the junction of laminated yoke caused by grounding.
(5) with a submersible pump device large and medium-sized transformer, the submersible pump bearing wear, metal powder into the tank, silt the bottom of the tank, under the action of electromagnetic force to form a bridge, the iron yoke and pad feet or bottom connected to form more Point to ground.
(6) oil-immersed transformer tank cover on the thermometer seat cover is too long, and the folder on the pieces or iron yoke, collide along the edge of the column to form a new grounding point.
(7) oil-immersed transformer oil tank has fallen into the metal foreign body, this kind of metal foreign body makes the core lamination and the box structure, forms the earth.
(8) under the folder and iron yoke ladder between the wood block damp or surface is not clean, with more sludge to make its insulation resistance value is reduced to zero, the composition of multi-point grounding.
3 multi-point grounding occurs when the anomaly
(1) eddy current in the core, iron loss increases, the local core overheating.
(2) more serious ground, but also a long time without treatment, continuous operation of the transformer oil and winding will lead to overheating, so that the gradual aging of oil-paper insulation. Will cause the core laminated two pieces of insulation aging and fall off, will cause a larger core overheating, the core will be burned.
(3) a long time multi-point grounding, so that oil-immersed transformer oil degradation and produce flammable gas, the gas relay action.
(4) due to core overheating so that the body in the wood pad and clip pieces of carbonation.
(5) serious multi-point grounding will blow the ground wire, so that the transformer lost the normal point ground, the consequences could be disastrous.
(6) multi-point grounding will cause discharge phenomenon.
4 multi-point ground fault detection
Transformer windings and core is the transmission and transformation of the main components of electromagnetic energy. Ensuring that they can be run is a matter of concern. Statistics show that the failure caused by core problems, accounting for the total transformer accident in the third. The manufacturing sector on the core of the transformer core has attracted attention, and the core can be * grounded, core ground monitoring, and to ensure that one point of grounding have been technical improvements. The operation department also put the detection and found that the core failure to a considerable height. However, the transformer core failure is still occurring frequently, the main reason is due to multi-core ground and core grounding caused by poor. Now two kinds of fault conditions to determine and deal with an approach to make an introduction.
1 core normal need a little grounding reasons
During normal operation of the transformer, there is an electric field between the charged windings and the tank, while the core and other metallic components are in the electric field. As the capacitance distribution, field strength varies, if the core is not * ground, will produce charge and discharge phenomena, destruction of solid insulation and oil dielectric strength, so the core must have a little * ground.
Core composed of silicon steel sheet, in order to reduce the eddy current, the chip has a certain insulation resistance (usually only a few ohms to tens of ohms), due to great inter-chip capacitance in the alternating electric field can be seen as access, which core In only a little ground can be laminated to the core laminations potential clamped to ground potential.
When the core or metal components such as two or more than two points (multi-point) grounding, the ground will cause a closed loop, the key chain part of the magnetic flux, induced electromotive force, and the formation of loops, resulting in local Overheating, and even burned iron core.
Transformer core only one point ground, is the normal * ground. The core must be grounded and must be grounded.
Core failure is mainly caused by two reasons: First, the construction process caused by poor short circuit, the second is due to accessories and external factors caused by multi-point grounding.
2 core multi-point grounding type
(1) after the completion of the installation of the transformer, the fuel tank is not on top of the transport pins flip over or removed, constitute a multi-point grounding.
(2) as the core clip pieces from the core column too close, the core lamination for some reason after the tilt, touching the clamp pieces, the formation of multi-point grounding.
(3) iron yoke screw bushing is too long, and iron yoke lamination of touch, constitute a new grounding point.
(4) iron core under the clamp feet and iron yoke between the insulation board off or damaged, so that the foot yoke at the junction of laminated yoke caused by grounding.
(5) with a submersible pump device large and medium-sized transformer, the submersible pump bearing wear, metal powder into the tank, silt the bottom of the tank, under the action of electromagnetic force to form a bridge, the iron yoke and pad feet or bottom connected to form more Point to ground.
(6) oil-immersed transformer tank cover on the thermometer seat cover is too long, and the folder on the pieces or iron yoke, collide along the edge of the column to form a new grounding point.
(7) oil-immersed transformer oil tank has fallen into the metal foreign body, this kind of metal foreign body makes the core lamination and the box structure, forms the earth.
(8) under the folder and iron yoke ladder between the wood block damp or surface is not clean, with more sludge to make its insulation resistance value is reduced to zero, the composition of multi-point grounding.
3 multi-point grounding occurs when the anomaly
(1) eddy current in the core, iron loss increases, the local core overheating.
(2) more serious ground, but also a long time without treatment, continuous operation of the transformer oil and winding will lead to overheating, so that the gradual aging of oil-paper insulation. Will cause the core laminated two pieces of insulation aging and fall off, will cause a larger core overheating, the core will be burned.
(3) a long time multi-point grounding, so that oil-immersed transformer oil degradation and produce flammable gas, the gas relay action.
(4) due to core overheating so that the body in the wood pad and clip pieces of carbonation.
(5) serious multi-point grounding will blow the ground wire, so that the transformer lost the normal point ground, the consequences could be disastrous.
(6) multi-point grounding will cause discharge phenomenon.
4 multi-point ground fault detection
