EXPERIENCE WITH ELECTROSTATIC FIELDMETER INSTRUMENTS WITH NO EARTHING OF THE ROTATING CHOPPER
EXPERIENCE WITH ELECTROSTATIC FIELDMETER INSTRUMENTS WITH NO EARTHING OF THE ROTATING CHOPPER
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使用旋转斩波器不接地的静电场计仪器的经验
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
J. Chubb
中科院分区：
文献类型：
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作者：
J. Chubb
在1990年，两个新的设计的“外地磨”现场仪表被描述[2]，不使用传统的安排与一个双旋转斩波器。所描述的仪器是基于“恒定电容”和“背靠背”场计操作。本文件报告了1990年以来在根据上述两项原则操作商业票据方面取得的经验。还包括高性能和可靠的长期连续运行所需的功能的意见。经验表明，虽然“背靠背”的现场仪表方法看起来更复杂，但在机械和电子方面，可以毫无困难地处理这些复杂性，从而可以实现显著的益处。避免旋转斩波器接地的主要好处是：1）避免接地电刷的磨损：这意味着长而安静的工作寿命，仅受电机驱动和轴承的限制2）避免接地电刷的阻力：这意味着在高旋转速度下容易操作从而快速响应的磁场计是可行的3）避免了对用于接地电刷的特殊贵金属合金的需要，所需的仔细的机械设置以及随着电刷磨损而逐渐降低的零噪声。为了最小化污染的影响，传感区域内的所有表面都需要镀金，并且表面之间的间隙需要很大，以最小化灰尘和表面污染的影响，并避免纤维桥接的风险。对于在潮湿环境中的操作（例如用于测量大气电场），临界间隙需要至少为6mm以避免水桥接。需要长的表面绝缘路径。
In 1990 two novel designs of ‘field mill’ fieldmeter were described [2] which do not use the traditional arrangement with an earthed rotating chopper. The instruments described were based on ‘constant capacitance’ and ‘back to back’ fieldmeter operation. This paper reports the experience gained since 1990 in the operation of commercial instruments based on both the above principles. Also included are comments on features required for high performance and reliable long term continuous operation. Experience has been that although the ‘back to back’ fieldmeter approach appears more complex, both mechanically and electronically the complexities can be handled without difficulty so that the significant benefits can be realised. The main benefits from avoiding the need to earth the rotating chopper are: 1) avoidance of wear of earthing brushes: which means long and quiet operational life, limited only by the motor drive and bearings 2) avoidance of drag of earthing brushes: which means easy operation at high rotational speeds so fast response fieldmeters are feasible 3) avoidance of the need for special precious metal alloys for the earthing brushes, the careful mechanical setting required and the progressive degradation of zero noise as brushes wear. To minimise the influence of contamination all surfaces within the sensing region need to be gold plated and gaps between surfaces need to be large to minimise the influence of dust and surface contamination and to avoid the risk of bridging by fibres. For operation in wet environments (for example for measurement of atmospheric electric fields) critical gaps need to be at least 6mm to avoid water bridging. Long surface insulation paths are needed.