ELECTROSTATIC DISCHARGE

ELECTROSTATIC DISCHARGE (ESD)

STATIC ELECTRICITY  TAKEN SERIOUSLY  

We are all familiar with the naturally occurring static electricity, associated with thunderstorms  which is caused by  the friction of air molecules  in the upper atmosphere, an  action which results in often quite spectacular lightning displays. These occurrences are a vital atmospheric  interaction  which is essential to the survival of all  species of life on this earth. 

 

Electrostatic charge accumulation,  generated either naturally in the atmosphere or by  man made technology,  can be destructive when upon discharge,   a resulting spark  may ignite  volatile liquids  or gases,  causing  fire or explosion.  Control of electrostatic discharge (ESD) is essential in these circumstances.  ESD can be described as the action of  the transfer of  accumulated electrostatic charges,  which remain inert on the surface  of an object until contact is made with  another  conductive or semi-conductive object, even a human being. ESD can produce a  visible spark.  

 

IN THE HOME AND WORKPLACE

In our immediate  environment, electrostatic charges are also generated  artificially  by photocopiers, air conditioning, computers in the office and by appliances such as hair dryers, dishwashers, washing machines and  cooling fans.

 

Examples  of  ESD-  A newspaper columnist  was literally thrown from his chair  by the shock as he switched on the computer in his office .The cause?  Electrostatic discharge  (ESD) of the considerable  magnitude of the  charges  which had accumulated on his body mass as a result of  the   synthetic clothing he was wearing  and the  office furnishings. ESD has  the potential to cause malfunction of  some computers when these  charges are transferred from the hand of the operator to the  PC.  ( Sydney Morning Herald 29.6.1992).   

 

An  elderly lady was reported to have received an electrostatic shock while using a landline telephone, then  became   hypersensitive to all  electrical appliances.  In another instance after replacing several phones for a lady an Australian   telephone company was unable to provide a  telephone  handset that  was impervious to  ESD. The problem was found to be the customer’s unusually  high  rate of ESD  which  was severe enough to cause the phone to  malfunctioned.    The phone company solved the problem by providing  her with an anti static table mat.  Many minor incidents of a similar nature have been reported.  People  also report being often painfully ‘zapped’ on touching the metal supermarket trolley or  the car door on leaving the vehicle.

 

All synthetic materials, are known to generate electrostatic charges. Many people are familiar with the spark and 'ZAP' or mini shock produced by the electrostatic discharge (ESD)  which occurs at the touch  as we  leave  a motor vehicle, or on removing synthetic clothing, combing or brushing hair with nylon comb/brush or even on touching another person.  These effects are more prevalent in cold or hot, low humidity atmospheric conditions. Electro static charges  produced under these circumstances may be ignored by some individuals, no more than a nuisance to others but for the hypersensitive individual, it can be a source of varying degree of stress. Calibrated instruments are used by industry to determine the magnitude of electrostatic charges.

 

AREAS WHERE  ESD CONTROL IS NECESSARY :

*     In the hospital operating theatre synthetic fabrics are banned as they  could generate static sparks.

*     Where explosives are used, the operator of the detonator must be 'earthed' so that he does not                          accidentally  trigger the detonating device with the static charges that his body may carry.

*      anti-static solutions are sprayed on machine benches and cutting trenches in clothing factories to prevent      static  'cling' from synthetic fabrics during manufacture of goods.

*      process workers in the electronics industry must use static control methods in order to prevent static charges  transferring to the delicate electronic components and causing malfunction of the product. Guarantee of              product reliability  could not be given  otherwise.

*     To prevent electrostatic accumulation  which creates a risk of  explosion or fire,  motor vehicles carrying  volatile liquids are ‘grounded’ by  an attached  metal chain dragging from the rear of the vehicle, which  touches the road at all times.  

*     Somewhat less dangerous is the  packaging of goods where handling of plastic bags can produce  considerable static charges on the body mass of the packer. This has been observed to   hinder  work     performance.   Static control  has been found to improve work efficiency in  these  situations.    

 

It is reported that most Mazda new model cars, have a small anti-static panel near the inside door handle - this         panel is earthed and requires a light touch to comfortably discharge static from the body.  Anti-static straps             attached to the rear of a car have been found to benefit  both driver and passengers and to  reduce stress from  drivers  though 'sensitivity' may not be evident.  

As demonstrated,  adequate electrostatic discharge  (ESD)  control  is essential in many industries.  This paper will illustrate how  ESD  control  has been  found to benefit   many  people  providing  greater  comfort,  better work performance and well-being . 

  

STATIC ELECTRICITY  -   NOT  JUST A PARTY TRICK

AFFECTS  ON  MOOD AND  STRESS LEVELS

Most of us have seen  the paper and nylon comb ‘party trick’ which is one  way to demonstrate  static electricity.  Removing synthetic clothing or brushing hair with a nylon comb/brush, in a darkened room  can  produce  a visual electrostatic  ‘display’ of  ESD.    

Greater  than  we might expect,   is the degree of  involvement of   ESD in  our lives     Most people are unaware that static electricity is  generated by the friction of the synthetic  upholstery fabrics   in motor vehicles, furniture  and by  synthetic  soled footwear scuffing against  synthetic floor coverings.  Friction of all synthetic  materials, is  known to generate electrostatic charges.

 

Many of us are familiar with the  'ZAP' or mini shock produced by the electrostatic discharge (ESD) of charges we have accumulated on our body mass.  This can occur  as we  touch  any conductive or semi-conductive object,   the metal  as we  leave  a motor vehicle, or even upon touching another person.  These effects are more often observed in cold,  hot and  low humidity atmospheric conditions. ESD occurring  under these circumstances may be ignored by some individuals, no more than a nuisance to others, but for the hypersensitive individual, it can be a source of moderate to severe stress.  In atmospheric  conditions that generate natural electrostatics, school children become overactive and less easy to control according to teachers.  This same effect may well occur when children are in an environment where artificially generated electrostatic charges are present, in  large shopping complexes and other air-conditioned  premises, for instance.

 

Little attention though is paid to the physical and psychological  discomfort of the unfortunate individual who is adversely affected by the accumulation of electrostatic charges and  by electrostress in general.  Reported effects are  moderate to severe debilitation,  clumsiness, memory lapses, behaviour problems and  various degrees of discomfort, stress and  pain.    The ‘sick building syndrome’ list of symptoms is almost identical.

 

SEEKING A SOLUTION

In response to many queries from people who were seeking relief from the stress levels induced by  our modern  indoor environment, now saturated with electric and magnetic and electrostatic  emissions and charges,  advice was sought from the ESD industry with some success.  On observing electrostatic control -  that is ‘grounding /earthing’  the person  and using other methods of reducing static build-up,  stress levels were found to be significantly reduced

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STATIC ELECTRICITY AND EFFECTS ON HEALTH

Static electricity produced by electrical equipment and friction of synthetic furnishing fabrics, is very much evident in our modern homes, offices and in motor vehicles.  An increasing number of people are developing a hyper-sensitivity to excessive exposure to these artificially generated   fields of electrical energy. The condition, becoming known as ELECTROSTRESS or ElectroHyper-Sensitivity (EHS) can develop due to chronic exposure to this environment.  

 

The EHS  individual can react adversely to any frequency in the electromagnetic spectrum, including static electricity,  experiencing stress which translates to  a variety of symptoms  ranging from moderate to severe in intensity.  Some reported effects are:

*          muscle weakness, draining of energy, excessive fatigue.

*          clumsiness, person becoming accident prone

*          dry eyes

*          memory lapses

*          behaviour problem

We have found  from experience and  observation that very dry  skin and hair adds to the  individual  susceptibility to EHS and ESD stress.  

Little is known of, or documented on the effects of electrostatics on the human system and  symptoms are often attributed to other factors.  Anecdotal evidence from EHS people, working and living in an artificial electrical atmosphere, suggests that it may be a problem of considerable proportions. The ‘sick building’ syndrome  is  a modern phenomenon.  In Sweden and UK there are studies underway to determine the extent and cause of ElectroHyperSensitivity  (EHS).

 

ANECDOTE                       

Worth noting is the reported case of a child’s health improving  after electrostatic control was employed in the bedroom.  Initially,  magnetic and electric fields were eliminated from his room, yet some physical symptoms lingered.  The laminated surface of the bedroom furniture was found to hold a large electrostatic charge, which transferred to the body  mass of the child.    The furniture was treated with an anti-static solution and the  child recovered completely.

 

SYNTHETIC   FABRICS AND ELECTROSTATICS

 Most people are not aware that static electricity is also generated by the friction of synthetic fabrics in clothing  and  upholstery  in motor vehicles and by  synthetic  soled footwear against floor coverings.  

 

ADAPTING  INDUSTRIAL  ESD CONTROL   FOR PERSONAL COMFORT  

People employed in  an industry where ESD  control is used may be considered fortunate as he/she is also protected from the physical effects that  ESD  may induce.     ESD control is used  in industry for the   protection of the equipment  and is the sole reason for installation of the system   It appears not to have  occurred to anyone -  at  least  there is no documentation to support the  notion -  that  the operators  may   perform  more efficiently due to lessening of stress caused by the  electrostatic charged  environment. 

    

In 1989, while seeking assistance  for means of relieving  stress from exposure to electric and magnetic field exposure,  the author was alerted to the electrostatic effect and resulting stress.   By   means of  ESD control, in the form of the  grounded/earthed anti-static mat  or wrist strap, the  considerable stress  experienced from sources of

electrostatic charge  was  reduced   to a tolerable level.   Since that time,  electrostatic control  has  lessened the  discomfort  of many people, especially those  who are electrically hyper-sensitive (EHS). This  grounding method can  be used in many situations to relieve or to prevent  electrostress.

 

PERSONAL EXPERIENCES  

Following is a sample of the  empirical evidence supplied  by  people  who have derived benefit from  observing  control of electrostatic accumulation and electrostatic discharge (ESD).   The original signed letters are on file.  Increased energy levels  and general  well-being are some benefits reported by  people who have avoided  electrostatic build-up  or  to control often painful electrostatic discharge (ESD)  from the body mass. ESD occurs on  body contact with another conductive or semi-conductive object as explained earlier..  ESD control has   greatly reduced or completely  eliminated previously experienced stressful symptoms.  Controlling the ESD can be achieved by using a  suitably earthed /grounded antistatic wrist strap or table mat.   Details below.

Some  reported symptoms and benefits of ESD control:

·        Tired and gritty eyes   are no longer a  problem

·        Operating a  sewing machine  is  now less stressful, energy levels increased

·        A woman  with  Electro Hyper-Sensitivity   (EHS)    can now   tolerate the dentist’s  surgery, where the electrically operated chair  and fluorescent lights were formerly a problem.  She takes an anti static table MAT   with her on  each visit.

·        Operating a computer is now less  stressful  - work performance  increased.  

·        Induced  Repetitive Strain Injury (RSI ) symptoms which occurred within  approximately 45 minutes at the computer –  have been eliminated  

·        Touching the MAT while  using the telephone  has  lessened stress. Electro static  charges and electric and  magnetic field  emissions  from  landline  telephones  causes stress for some people. People have found they could use the phone for the first time in a number of years after observing  ESD avoidance.  

·        Irritability lessened, better  sleep and work performance  experienced  since  using the MAT  in the house where  considerable  electrostatic  charges accumulate. The house is situated adjacent to an electricity substation.    

For computer use  -  a  grounded, (earthed )   glass  shield for the computer monitor screen  is also advised. This will  eliminate 90% of the electric field emissions from the monitor screen.

 

HOW THE MAT WORKS.

P.V.C. materials or plastics generally,  can be turned into “semiconductors” by adding certain compounds.  These materials are not quite conductors and not quite insulators.  They have the ability to drain electrostatic discharge (ESD) at a slower rate than conductors so reducing the possibility of spark.  We call these materials “static dissipative”.     

                                                                                     

The MAT functions as a ‘grounding’ device, eliminating the electrostatic charges which accumulate on the body mass in certain atmospheric conditions.

 

The P.V.C. MAT is a dissipative material which, upon skin contact allows the ESD   to take place via the attached grounding lead,  in a controlled manner.  Incorporated in the grounding lead,  as a safety factor,  is a 1 MegaOhm electrical resister.  The MAT is connected to the earth pin only of the grounding lead.  The integrity of the grounding system of the building is extremely important and should be checked by an electrician.

The resistivity of the P.V.C. material can be scientifically determined.   It falls into the range of 10 9   OHMS per square (nom).  (Ref: USA and European Ranges for Description of Materials.  EIA – IS5A 1985)

 

The ANTI-STATIC MAT is placed partially under the keyboard of a computer or electric typewriter, allowing  a section exposed for hand contact with the MAT.  Developing a routine of frequently touching the MAT will allow accumulated static to be discharged harmlessly to ground, via the earthing system of the electricity supply. The MAT does NOT use any electricity.  It can be located to be used while ironing, using electric typewriters, the telephone and computers.  Discharging static by touching the MAT  in these circumstances is found to reduce electrostress.   Anti static wrist straps work well also but are not as convenient as the mat.

The following tips are useful:

·        Wear natural fibre clothing ,

·        use a perfume free skin moisturizer  

·        use a hair product to prevent dry  hair.

·        Use an anti static  solution to wipe desk and bench surfaces  This is available from hosiery  counters and fabric stores.

·        use the same solution on spectacle lenses

 

THE HOUSEHOLD ELECTRICAL EARTHING (GROUNDING)   SYSTEM

In older dwellings, as electrical safety standards require, the household water supply pipe has always been used as the means of 'earthing' the household electrical supply by bonding the earth wire to the galvanised or copper water pipe.  Due to the more recent practice of using PVC piping for plumbing systems, electricity safety standards now require the mandatory practice of the installation of a 1.5 metre copper electrode, at the site of the electricity meter and for it to be exposed to the weather.  The  effectiveness of  any static control device is dependant on the integrity of  the earthing/grounding  system of the building.  Therefore it is recommended that the soil surrounding the copper electrode should be kept damp at all times,  as the terrain may be poorly conductive and in very dry weather can be less effective than desired.  Though the electrode will be installed to electrical safety standard requirements, empirical  evidence indicates that the moisture content of the surrounding area is essential  for  EMR  considerations.    

 

ABBREVIATIONS

EHS    = HYPERSENSITIVITY = An unusual or excessive physical or behavioural response to electric, magnetic  emissions and electrostatic charges. The effect can occur immediately or as a delayed reaction producing  either a debilitating or a  temporary  hyperactive condition,  followed by period of debilitation as well as a range of  physical and psychological symptoms in the  living organism.

ESD    =    Electrostatic Discharge  

 

   INFORMATION