IEC TR 60479-3:1998 pdf download – Effects of current on human beingsand livestock – Part 3: Effects of currents passing through the body of livestock

IEC TR 60479-3:1998 pdf download – Effects of current on human beingsand livestock – Part 3: Effects of currents passing through the body of livestock.
This technical report indicates values for the electrical impedance of the body of livestock as a function of the touch voltage, the degree of moisture of the hide or skin and the current path
At this time values are only available for cattle.
It describes the effects of sinusoidal alternating current within the frequency range from 15 Hz to 100 Hz passing through the body of livestock.
NOTS — Iffiless olh.rw’. spocihed, the cutrenl vakies dilind In this technical report are r.m.s. vabies.
1.2 General remarks
For a given current path through the body, the danger depends mainly on the magnitude and duration of the current flow. However, the timecurrent relations specified in clause 5 are, in many cases. not direcity applicable in practice for designing protection against electric shock. The necessary criterion Is the admissible limit of touch voltage (I.e. the product of the current through the body and the body impedance) as a function of time. The relationship between current and voltage is not linear because the impedance of the body of livestock varies with the touch voltage, and data on this relationship Is accordingly required.
The different parts of the body of livestock (such as the hide, skin, blood, muscles, other tissues and joints) present to the electric current an impedance composed of resistive and capacitive components. The dry hides in particular, in the range of voltages up to several hundred volts, frequently present a high resistance.
The value of these impedances depends on a number of factors, in particular the species of the animal, the current path, the touch voltage, the duration of current flow, the frequency. the degree of moisture of the hide andJor the skin, the surface area of contact, the pressure exerted and the temperature.
The impedance values indicated In this report result from close examination of the experimental results available from measurements carried out principally on living animals.
Clause 5 is primarily based on the findings related to the effects of current at frequencies of 50 Hz or 60 Hz which are the most common in electrical installations. The values given are deemed applicable to the frequency range from 15 Hz to 100 Hz, threshold values at the limits of this range being higher than those at 50 Hz and 60 Hz.
This clause considers principally the risk of ventricular fibrillation which Is the main cause of fatal accidents in that range of frequencies.
1.3 Normative references
The following normative documents contains provisions which, through reference in this text, constitute provisions of this technical report. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this technical report are encouraged to investigate the possibility of applying the mast recent editions of the normative documents indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.
IEC 60479-1 :1994, Effects of current on human beings and livestock — Part 1: General aspects
IEC Guide 104:1997. The preparation of safety publications and the use of basic safety pubbcal,ons and group safety publication
ISO/lEG guide 51:1990, Guidelines for the inclusion of safety aspects in standards
1.4 DefinItions
For the purpose of this part of IEC 60479, the definitions given in lEG 60479-1, as well as the following definitions apply.
1.4.1
internal impedance of the body (Z)
impedance between two electrodes in contact with two parts of the body, neglecting hide and skin impedances and the impedance of the hooves, if any
1.4.2
impedance of the hide and skin (Zp)
impedance between an electrode on the hide and/or skin and the conductive tissues underneath
1.4.3
impedance of the hoof (4)
impedance between an electrode under the hoof and the conductive tissues above It
1.4.4
total impedance of the body (ZT)
vectorial sum of the Internal impedance and the impedances of the hide, skin and hooves, If any (see figure 1).