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(29 October, 2015)

The business of John Chubb Instrumentation was sold to Chilworth Technology in February 2009. Since then I have carried out consultancy work on a number of projects, written a few papers and developed a number of other interests - notably in art and in a couple of philosophy groups. I have also had published my book "An Introduction to Electrostatic Measurements".

Since the sale of JCI I have taken the opportunity to publish papers on a number of the measurement techniques we developed at JCI, which were not included in my book, and to report on a few more recent studies I have carried out. These are listed below together with the abstracts of these papers.

 

  1. "Enhanced performance of field mill fieldmeters for alternating electric fields" Paper with John Harbour submitted to J Electrostatics, October 2015

    Standard field mill fieldmeters have a frequency response limited by the chopping frequency and show low frequency beat signals in their output when observing alternating electric fields near the chopping frequency and near harmonics of this. The paper reports experimental studies with a dual phase sensing system that show how the frequency response can be extended to at least 150 kHz with uniform sensitivity and beating problems inhibited.

  2. "Limitations on the performance of field mill fieldmeters with alternating electric fields" J Electrostatics 78 2015 p1-3.

    The response of field mill type electrostatic fieldmeters to alternating electric fields is limited by the chopping frequency. Measurement reported here show that alternating frequencies at the chopping frequency, and related harmonics, can create confusing low frequency outputs. Hence care is needed for interpreting observations where such alternating electric fields may be present.

  3. "How should the electrostatic suitability of materials be assessed?" Paper submitted to J Electrostatics July 2015.

    There is no one single test that shows the electrostatic suitability of materials for all situations. The paper offers some more philosophic thoughts on the basic approaches that need to be adopted for methods to assess the electrostatic suitability of materials. In essence the recommendation is that test methods should be, or be close to, the relevant practical operation and situation. Alternative, perhaps more convenient measurement methods, need to be shown to match the results achieved in the relevant practical operation and situation.

  4. "A 'Static' business" Physics World, January 2015. An outline history of the business of John Chubb Instrumentation.

  5. "COMPARISON OF ATMOSPHERIC ELECTRIC FIELD MEASUREMENTS BY A POLE MOUNTED FIELDMETER AND BY A HORIZONTAL WIRE ANTENNA" J Electrostatics 73 2015 p1-5

    The studies reported show that measurements of atmospheric electric fields by pole mounted electrostatic fieldmeters can match measurements by a horizontal antenna wire. However, significant differences can arise. These differences are tentatively attributed to tribocharging actions during initial set up of the antenna system and by wind blown airborne particulates at the antenna wire. Pole mounted fieldmeters provide opportunity for long term unattended measurements in quite adverse weather conditions with continuous checking of operational health against debris, spider webs, etc.

  6. "AN ALTERNATIVE METHOD FOR CHARGE DECAY MEASUREMENT TO ASSESS THE SUITABILITY OF MATERIALS"

    J Electrostatics 72 (5) 2014 p396-401

    A method of charge decay testing is proposed in which a localized electric field is applied by a fieldmeter to an area of the material to be tested. The variation of electric field is recorded as charge migrates across the surface. Arrangements are described for this method of testing and studies reported comparing results with corona and tribocharge decay measurements. Interesting differences are shown between the methods of testing.

    Induction charge decay testing is not proposed as a replacement for corona or tribocharge decay testing. It offers the opportunity for simpler instrumentation and measurement of faster charge decay times.

  7. "THE MEASUREMENT OF ATMOSPHERIC ELECTRIC FIELDS USING POLE MOUNTED ELECTROSTATIC FIELDMETERS" J Electrostatics 72 2014 (4) p295-300

    A pole mounted field mill type electrostatic fieldmeter provides a simple and practical way for measurement, and for long term continuous monitoring, of ground level atmospheric electric fields. The paper describes a number of studies of this measurement method. These show how atmospheric electric field values are derived from the response of the fieldmeter when earth bonded and its height above ground level. The response of the fieldmeter is calibrated via the linear variation of its response to voltage applied during the set up procedure. The studies confirm a linearity of fieldmeter response with height above ground and independence of mounting orientation.

  8. "ASSESSMENT OF THE ELECTROSTATIC SUITABLITY OF MATERIALS"

    by Ian Pavey and John Chubb was presented at the Electrostatics Society of America meeting Cambridge, Ontario, Canada June 12-14 2012. Papers available at: ( http://electrostatics.org/esa2012proceedings.html)

  9. "STUTTER TIMING FOR CHARGE DECAY MEASUREMENT" Paper presented at Institute of Physics "Electrostatics 2011" Conference, Bangor, April 2011. IoP Conference Series 301 2011 This paper, with John Harbour and Ian Pavey, describes the approach of "stutter timing" that has been developed to improve the accuracy of measuring charge decay times in the presence of noise in compact and portable charge decay test instrumentation. The approach involves starting and stopping the timing clock as the noisy signal rises above and falls below the target threshold voltage level. Paper presented at Institute of Physics "Electrostatics 2011" Conference, Bangor, April 2011. IoP Conference Series 301 2011
  10. "OPERATIONAL HEALTH MONITORING FOR CONFIDENCE IN LONG TERM ELECTRIC FIELD MEASUREMENTS"

    J. Electrostatics 68 2010 p469-472. The paper by John Chubb and John Harbour describes practical aspects of electrostatic fieldmeter instrumentation for long term monitoring of electric fields in adverse environmental conditions. Examples of applications have been in studies of tank washing on large crude oil tankers and measurement of atmospheric electric fields. Particular attention is drawn to the technique developed for continuous monitoring of operational health to justify confidence in observations.
  11. "LETTER TO THE EDITOR: ASSESSING THE ELECTROSTATIC SUITABILITY OF GARMENTS FOR USE IN ELECTROSTATICALLY SENSITIVE WORK AREAS" J. Electrostatics 68 2010 p404

  12. "Letter to the Editor: Assessing the electrostatic suitability of cleanroom garments"

    An IEC Standard document has recently been published IEC 61340-9-4 "Electrostatics - Standard test methods for specific applications - garments". This states that the electrostatic suitability of cleanroom garments is to be judged solely on the basis of resistivity measurement. It is important that the limitations of this approach are appreciated.

    Cleanroom Technology, April 2010

  13. "ANALYSIS OF LONG CORONA CHARGE DECAY TIMES"

    Experience has shown that with long charge decay time materials the local charge decay time constant comes to increase linearly with time during the progress of charge decay. This is an empirical result. This linear increase provides the basis for calculating the time to 1/e and/or to 10% from much shorter periods of observation. This approach is useful for assessing and comparing materials that have decay times over say 10,000 seconds.

    Paper, with H Walmsley, published in J Electrostatics 68 2010 p284-286.

  14. "RISKS OF IGNITION FROM UNGROUNDED TYPE D FIBC"

    The paper, with Paul Holdstock, shows how the effective resistivity of conductive features within FIBC type fabrics can be measured, without electrical contact, from the variation of shielding performance with frequency. From such measurements an empirical acceptance criterion has been derived that matches well to the results of gas probe ignition tests. Studies are proposed to provide reliable criteria for assessing FIBC Type D bag materials and to help optimize FIBC fabric design.

    J Electrostatics 68 2010 p 145-151

  15. "LETTER TO THE EDITOR" ESDA Threshold 26 (5) Sept/Oct 2010 p5

  16. "AN INTRODUCTION TO ELECTROSTATIC MEASUREMENTS"

    Book by John Chubb published by Nova Publishers (ISBN: 978-1-61668-251-4)
  17. The book presents the experience John Chubb has gained from his work on static electricity from over 50 years of involvement. This is not an academic textbook and does not aim to cover every aspect of electrostatics. Rather it outlines the features required for good quality electrostatic measurements and presents the results of the experience gained from devising, developing and manufacturing a range of practical instruments.

    The book concentrates on the design and practical features of field mill electrostatics fieldmeters, on the use of corona charge decay as an appropriate method for assessing the electrostatic suitability of materials, on the use of capacitance loading as an additional relevant characteristic of materials, on a novel method for measuring the ability of materials to provide shielding against transient electric fields and on methods for calibration of electrostatic measuring instruments. Experience is described from a variety of practical studies of electrostatic problems.



John Chubb, email: jchubb@infostatic.co.uk