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高压真空断路器以具备良好的灭弧特性,适宜频繁操作,不检修周期长的优势

发布时间:2020-01-17   浏览次数:3956

高压真空断路器以具备良好的灭弧特性,适宜频繁操作,不检修周期长的优势,在当今我国电力工业城乡电网改造、化工、冶金、铁道电气化以及矿山等行业得到了广泛的应用,受到了使用部门的普遍好评。

高压真空断路器的使用优势主要是指真空灭弧室,但其不检修周期长的特性并不等于不检修和免维护。针对真空断路器整体而言,真空灭弧室仅是一个组成元件,诸如操动机构、传动机构、绝缘件等,仍为保证真空断路器各项技术性能的重要组成部分。对于各组成部分的正常维护,以达到真空断路器满足的使用效果是非常必要的。

1 真空断路器的安装要求

真空断路器在制造厂未作出承诺时,使用现场进行常规的例行检查是很必要的,尽可能地避免盲目的自信心理。

(1)安装前对真空断路器应进行外观及内部检查,真空灭弧室、各零部件、组件要完整、合格、无损、无异物;

(2)严格执行安装工艺规程要求,各元件安装的紧固件规格必须按照设计规定选用;

(3)检查极间距离,上下出线的位置距离必须符合相关的专业技术规程要求;

(4)所使用的工器具必须清洁,并满足装配的要求,在灭弧室四周紧固螺丝,不得使用活扳手;

(5)各转动、滑动件应运动自如,运动磨擦处应涂抹润滑油脂;

(6)整体安装调试合格后,应清洁抹净,各零部件的可调连接部位均应用红漆打点标记,出线端接线处应涂抹有防腐油脂。

2 使用中对于真空断路器机械特性的调整

通常,真空断路器在出厂调试时,对于其机械性能诸如开距、行程、接触行程、三相同期、分合闸时间、速度等都进行了比较完整的调试,并随机附有调试记录。一般在使用中现场只需对三相同期、分合闸速度和合闸弹跳稍许调整合格之后,即具备了投运条件。

(1)三相同期的调整:

针对测试中合、分闸开距差异较大的一相,如该极合闸过早或过迟,将该极的开距稍许调大或者调小点,只需把该极绝缘拉杆的可调活接头旋入或者旋出半圈,一般可调整使合、分闸不同期性达到1mm以内,获得比较理想的同期参数较佳值。

(2)合、分闸速度的调整:

合、分闸的速度受到多方面因素的影响,而在使用现场可调整的部位仅是分闸弹簧和接触行程。分闸弹簧松紧程度,对合、分闸速度产生直接的影响,而接触行程(指触头压力弹簧的压缩量),仅对分闸速度产生主要的影响。假如合闸速度偏高而分闸速度偏低时,可以将接触行程稍许增大,或者将分闸弹簧拉紧一点即可;反之调松一些。假如合闸速度比较合适,而分闸速度偏低,则可调整总行程使其增大0.1~0.2mm,此时各级的接触行程均增大了0.1~0.2mm左右。其分闸速度也会上升;反之分闸速度过高时,也可将接触行程调小0.1~0.2mm,分闸速度也会降低。

当完成三相同期与合、分闸速度的调整之后,切记要重新对各极的开距和接触行程进行测量修正,并应符合真空断路器产品的相关规定。

(3)合闸弹跳的消除:

真空断路器普遍存在着合闸过程中触头的弹跳问题。分析其产生的主要原因:一是合闸冲击刚性过大,致使动触头发生轴向反弹;二是动触杆导向不良,晃动过大;三是传动环节间隙过大;四是触头平面与中心轴垂直度不好,碰合时产生横向滑动等所致。

对于已经形成的产品,整机结构刚性已成定局,现场一般无法改变。对于动触杆导向不良,在同轴式结构中,触头压簧与导电杆是直接相联,无中间传动件,所以也就无间隙。对于异轴式结构的真空断路器,触头弹簧与动触杆之间有一个转向用的三角拐臂,用三个销钉连结,这就存在三个间隙,轻易出现合闸过程中的弹跳,这是消除弹跳的重点。同时还应重视触头弹簧始压端到导电杆之间传动间隙的调整,使传动环节尽可能紧凑,无缓冲间隙;假如因为灭弧室触头端面垂直度不好而产生弹跳,则可以将灭弧室分别转动90°、180°、270°安装,寻找上下接触面吻合位置,实在不行时则需要更换灭弧室。

在处理合闸弹跳过程中,切记将所有的螺丝都应拧紧,以免受到震颤的干扰。

High-voltage Vacuum Circuit Breakers: Application Advantages and Maintenance Essentials

High-voltage vacuum circuit breakers (HVVCBs), with their excellent arc extinguishing characteristics, suitability for frequent operation, and long maintenance-free periods, have been widely applied in China's power industry, urban-rural grid reconstruction, chemical, metallurgical, railway electrification, mining, and other industries. They have won universal praise from user departments.

The use advantages of HVVCBs mainly lie in the vacuum interrupter, but the "long maintenance-free period" does not mean no maintenance or maintenance exemption. For the entire vacuum circuit breaker, the vacuum interrupter is only a component, while operating mechanisms, transmission mechanisms, insulating parts, etc., remain critical to ensuring its technical performance. Regular maintenance of each component is essential to achieve the desired usage effect of the vacuum circuit breaker.

1. Installation Requirements for Vacuum Circuit Breakers

When the manufacturer does not make commitments, routine on-site inspections are necessary to avoid blind confidence.
(1) Before installation, conduct appearance and internal inspections of the vacuum circuit breaker to ensure the vacuum interrupter, components, and assemblies are complete, qualified, undamaged, and free of foreign objects.
(2) Strictly follow installation procedures, and select fastener specifications as per design requirements.
(3) Check the pole spacing and the position distance of upper/lower outlets to comply with relevant technical regulations.
(4) Use clean tools meeting assembly requirements; do not use adjustable wrenches for tightening screws around the interrupter.
(5) Ensure rotating and sliding parts move freely, and apply lubricating grease to friction points.
(6) After qualified installation and debugging, clean the equipment, mark adjustable connection parts with red paint, and apply anti-corrosion grease to outlet terminals.

2. Adjustment of Mechanical Characteristics during Operation

Generally, vacuum circuit breakers undergo comprehensive debugging of mechanical properties (such as opening distance, travel, contact stroke, three-phase synchronism, switching time, speed, etc.) before delivery, with debugging records attached. On-site adjustment usually only requires fine-tuning of three-phase synchronism, switching speed, and closing bounce to meet operation requirements.

(1) Three-Phase Synchronism Adjustment:
For the phase with the largest opening distance difference in testing, if the pole closes too early or late, slightly adjust the opening distance by screwing the adjustable joint of the pole's insulating pull rod in or out half a turn. This can generally adjust the non-synchronism to within 1mm for optimal parameters.

(2) Switching Speed Adjustment:
Switching speeds are affected by multiple factors, with on-site adjustable parts being the opening spring and contact stroke. The tightness of the opening spring directly impacts switching speeds, while contact stroke (compression of the contact pressure spring) mainly affects the opening speed.

  • If closing speed is too high and opening speed too low, increase contact stroke slightly or tighten the opening spring.
  • If closing speed is appropriate but opening speed is low, increase the total stroke by 0.1–0.2mm (contact stroke of each pole increases accordingly), which will raise the opening speed; conversely, reduce contact stroke to lower the opening speed.
    After adjusting synchronism and speeds, re-measure and correct the opening distance and contact stroke of each pole to meet product regulations.

(3) Elimination of Closing Bounce:
Closing bounce in vacuum circuit breakers mainly results from:

  • Excessive closing impact rigidity causing axial rebound of the moving contact;
  • Poor guidance of the moving contact rod with excessive 晃动 (sway);
  • Excessive clearances in the transmission chain;
  • Poor perpendicularity between the contact plane and central axis, causing lateral sliding during contact.
    For existing products, the overall structural rigidity is fixed, so on-site adjustments focus on:
  • For coaxial structures, the contact spring connects directly to the conductor rod without intermediate parts, minimizing clearances.
  • For non-coaxial structures, the triangular rocker arm connecting the contact spring and moving contact rod has three pin connections, creating clearances that cause bounce. Tighten transmission clearances between the contact spring and conductor rod.
  • If bounce is due to poor perpendicularity of the interrupter contact end face, rotate the interrupter 90°, 180°, or 270° to find the best fit; replace the interrupter if necessary.
    During bounce elimination, ensure all screws are tightened to prevent vibration interference.

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