Dr Clive Dalton
Amp: Unit of current. Watts divided by voltage.
Current: It is current and the duration and rat of its low which causes a shock. Increasing voltage increases current. Current decreases as resistance increases.
Capacitance: Ability to store a charge of electricity.
Capacitor: Stores electrical chares and ule as energy which builds up in the capacitor and is released by the SCR switch into the fence at approximately one per second.
Electrolysis: Corrosion which occurs when different metals are connected in a wet environment such as with electrical connections on a fence line.
Impedance: Combination of resistance, induction, frequency and capacitance (sometimes called AC resistance).
Induction: Power transfer without contact. For example – charging of dead or neutral fence wires which run parallel to live ones.
Insulator: A material across which current will not flow.
Joule: Unit of energy. Watts x seconds. Measures the ‘kick’ of a fence pulse.
Leakage: Loss of power conducted from the fence to the ground, caused by poor insulators, shorts and herbage growth on the wires.
Measurement: 500 ohms (2mS) which is the maximum a human or animal can conduct in the worst conditions e.g. with feet and hands in salt water. 5000 ohms (0.2mS) is the equivalent of a cow touching an electric wire. ( See Siemens).
Ohm: Unit of resistance. The ohm scale is a reverse one – so low numbers indicate heavy load and high numbers indicate a light load.
Outrigger: Electrified wire attached to conventional fence, supported in a way to keep stock from contacting the fence.
|Outrigger carrying hot wire on boundary fence|
Power consumption: Electricity consumption does not increase with leakageon the fence because most energisers operate on maximum all the time and the VDR’s absorb the unused surplus.
SCR: Silicon Controlled Rectifier which is a transistorised pulse switch.
Siemens: Unit of conductance, leakage or load. Reciprocal of ohm. 1 Siemens = 1 ohm, 1 millisiemens (mS) + 1000 ohms.
VDR: Voltage dependent resistor. Prevents voltage of more than 5000 volts from leaving the power unit by short circuiting the excess voltage.
Volt: Unit of electrical pressure which causes current to flow. Voltage = current x resistance.
Watt: Unit of power – both electrical and mechanical. 746 watts = 1 Horse power.
Acknowledgement of information source: To Gallagher New Zealand.