Utility model content
This utility model is in order to overcome above-mentioned deficiency of the prior art, it is provided that the electrification railway contact net bar-shaped suspended compound insulator of resistance to lightning impulse that a kind of rational in infrastructure, easy for installation and resistance to thunder level is high.
For achieving the above object, solution of the present utility model is: a kind of bar-shaped suspended compound insulator of resistance to lightning impulse, including plug, the first sheath, the full skirt being located on sheath, high-pressure side gold utensil, earth terminal gold utensil and at least one the first stress cone or the first stress cone group, described first stress cone or the first stress cone group are arranged on high-pressure side gold utensil and/or earth terminal gold utensil and plug junction, and described first stress cone group is combined by two the first stress cones boring end laminating. Insulator end gold utensil is the position that whole insulator is the most key, if this position of lightning surge impact failure, first sheath may be burnt, ftractureed and cause plug exposed, and plug burn impaired after can form carbonization road warp, this carbonization path is irreversible, along with the continuous extension in carbonization path, core brittle fracture will be caused and accidents caused. After the external insulation stress cone of correspondence is set; when acting on herein such as lightning impulse voltage or be neighbouring; stress cone dispersibles lightning current wave head; alleviate lightning current rising steepness; in addition stress cone place increases the thickness of external insulation; the structural safety of end metal fitting be can effectively protect, resistance to thunder level and the service life of insulator improved.
Preferably, the described bar-shaped suspended compound insulator of resistance to lightning impulse also includes the second sheath, and the second sheath described in described second sheath is wrapped in two stress cone junctions of stress cone group, and described second sheath is HTV silica gel sheath. HTV silica gel sheath can at utmost reduce the lightning impulse voltage that end metal fitting is subject to, and protects end metal fitting.
China's electrifing railway contacting net system maximum operating voltage is 27.5kV, and the resistance to thunder horizontal peak of Composite Insulators is 310kV, when lightning current is more than line lightning resisting level, can cause insulator surface flashover. Lightning stroke flashover time majority is only about 50s, and line-breaker has little time action, and when only flashover passage transfers power frequency short circuiting arc to, chopper just can trip. The relation of probability (probability of sustained arc) and field intensity that impulse flashover transfers stable power frequency arc to is:
��=(4.5E0.75-14) % formula (1-1)
In formula: ��-power frequency continued flow builds arc probability
Neutral point non-direct grounding system insulator chain average field-strength, unit is kV/m, wherein �� e is circuit rated voltage, and unit is kV; Lj is insulator string electrical arc distance, and unit is m.
After the FQBSG-25/12-890JHP rod post composite insulators produced at present and FQXSG-25/160/940HH composite rod insulator and improvement, the calculating contrast of same model composite insulator is as follows: (system operating voltage calculates by 27.5kV)
Example one: the FQBSG-25/12-890JHP insulator produced at present, it is known that arcing distance Lj=0.68m, E=27.5/ (2 �� 0.68)=20.22/m, is calculated as follows by formula (1-1):
��=(4.5 �� 20.22-14) %=28.90%
Same model insulator after improvement, it is known that arcing distance Lj=0.752m, E=27.5/ (2 �� 0.752)=18.22kV/m, is calculated as follows by formula (1-1):
��=(4.5 �� 18.22-14) %=25.68%
Example two: the FQXSG-25/160-940HH insulator produced at present, it is known that arcing distance Lj=0.72m, E=27.5/ (2 �� 0.72)=20kV/m, is calculated as follows by formula (1-1):
��=(4.5 �� 20-14) %=28.56%
Same model insulator after improvement, it is known that arcing distance Lj=0.881m, E=27.5/ (2 �� 0.881)=15.60kV/m, is calculated as follows by formula (1-1):
��=(4.5 �� 15.6-14) %=21.32%
After result of calculation shows to improve, the probability of sustained arc of insulator reduces by 3.22% and 7.24% respectively, effectively suppresses to stablize the generation of power frequency arc, and the safety of insulator under lightning impulse is highly beneficial by this.
The horizontal important aspect of resistance to thunder of Voltage for Insulators on HV Lines is depending on the lightning impulse flashover voltage of insulator chain, generally insulator chain positive polarity lightning impulse flashover voltage is lower than negative polarity, and therefore the flashover voltage of insulator calculates by positive polarity lightning impulse flashover voltage. Its computing formula is:
UI50=6.3Ld-37.5kV (peak) formula (1-2)
In formula: LdFor dry arc-over distance, unit is cm.
(example one) for improve after FQBSG (NL)-25/12-890JHP insulator:
Know according to formula (1-2): UI50=6.3 �� 75.2-37.5=466.26kV (peak) considers further that lightning impulse withstand voltage (UW1) it is generally the 90% of flashover voltage, therefore have:
UW1=466.26 �� 0.9=419.6kY (peak)
(example two) for improve after FQXSG (NL)-12/160-940HH insulator
Know according to formula (1-2): UI50=6.3 �� 88.1-37.5=517.53kV (peak) considers further that lightning impulse withstand voltage (UW1) it is generally the 90% of flashover voltage, therefore have:
UW1=517.53 �� 0.9=465.77kY (peak)
Result of calculation shows that the lightning impulse withstand voltage innovating the insulator after improving is respectively increased 109.6kY and 155.77kY than TB/T3199.2-2008 standard value.
Preferably, the described bar-shaped suspended compound insulator of resistance to lightning impulse also include can all pressure shading rings of equalizing voltage, described all pressures shading ring is arranged on high-pressure side and/or earth terminal gold utensil. The voltage's distribiuting of insulator is relevant with the direct-to-ground capacitance of self, and the voltage distribution of insulator that direct-to-ground capacitance is big is uniform, otherwise then uneven. The direct-to-ground capacitance of composite insulator is little, and voltage's distribiuting is uneven, and raises inhomogeneities with voltage and become apparent from, arrange after uniform shading ring can equalizing voltage, weaken the electric field force of parallel direction, be beneficial to suppression conducting particles and develop along face, it is prevented that flashover. Gold utensil place maximum field intensity can be reduced simultaneously, reduce electric field distortion degree, be beneficial to raising the flashover voltage of the insulator and discharge inception voltage, under lightning surge is impacted, electric arc can be attracted in self. Described all pressures shading ring is provided with to be raised; ring set one; ring footpath is parallel to cluster parachute; optimized dimensions is the 70% of insulator gamp diameter, does not affect arcing distance, without in-site installation; electric property is good; and the high temperature that moment produces can be derived when lightning impulse overvoltage impacts insulator, it is ensured that insulator temperature rise in this case is less than ambient temperature 20K, and protection insulator is injury-free.
Preferably, the described bar-shaped suspended compound insulator of resistance to lightning impulse also includes at least one second stress cone or the second stress cone group, described second stress cone or the second stress cone group are arranged on plug, described second stress cone group is combined by two the second stress cones boring end laminating, and described second stress cone is external insulation stress cone.
(1) it is effectively protected the structural safety of end metal fitting, improves resistance to thunder level and the service life of insulator;
(2) dynamics of the lightning impulse voltage that end metal fitting is subject to is decreased;
(3) ensure insulator temperature rise less than ambient temperature 20K, improve flashover voltage and the discharge inception voltage of insulator;
(4) simple and reasonable, easy for installation.