| Standards and concepts |
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Standards Electric fencing systems are meant to put off. The shock which is given off through touching by men or animal must be harmless. From this point of view the standards have been established to which the sold electric fencers must comply. In Europe these standards for electric fencing have been layed down in EN-standards. All apparatus which are developed and sold have to comply with these standards. There are readings which are relevant for the working and the capacity of the electric fencers, to which the output readings must comply: 1) The unloaded output charge is not allowed to exceed 10.000 Volt 2) The electric power peak in the resistance range of 100 – 500 Ohm is not allowed to be more than 20 Ampere. 3) The impuls energy in the resistance range of 100 – 500 Ohm is not allowed to be more than 5 Joule. Concepts With the explanation of the working of an electric fencer one uses a number of concepts which all have to do with electricity and energy. The most important concepts are mentioned below: Volt The unity of electric power is Volt. With electric fencing one uses the power to transfer the energy. Power U (V=Volt)=I (Energy A=Ampere) x R (resistance R=Ohm). Resistance The resistance is being measured in Ohm (R). The resistance slows the energy down. R=U/I. No resistance means short circuit, 1.000.000 W means a good insulation. An animal or a person has an average resistance of about 500 R. For this reason the power and the impuls energy with this resistance are the relevant values to compare electric fencers. Also conductors like wire, tape and cord have a resistance. The resistance of the various conductors is different. Aluminium wire has the lowest resistance and is therefore most suitable for very long fences. Ampère The power is being measured in Ampère (A). The power is the energy which flows through the wire.I=U/R. The duration and the strength of the power determine the shock/impuls put off by the electric fencer. The duration of the impuls determines how heavy the shock feels. This varies, depending on the type and brand of the electric fencer, between 0,1 and 0,5 microsecond. The distance between de shocks/impulses is about 1,2 seconds. Joule The energy which is being put off as power to the wire per shock/impuls, one measures in Joules. 1 Joule = 1 Watt (W) per second,= R*∫I²*dt One feels this energy when one is touching the fence wire. Loading energy The loading energy of the fencer shows how much energy is being absorbed from the power source (mains, (wet) battery) into the capacitor. A higher loading energy means that the fencer uses more energy. The proportion between loading energy and the impuls energy shows the efficiency of the fencer. A high proportion means that much energy is getting lost, which is not being put off to the conductors. Impuls energy Through the discharge of the capacitor the fencer puts off the stored energy to the conductors (wire, tape, cord etc.). One calls this shock/impuls discharge energy, also known as impuls energy. The impuls energy is often shown unloaded. Officially the impuls energy, which remains with a resistance of 500 W, has to be shown. This value determines the real strength of the fencer, the shock that the animal feels when it is touching the electric fence. |