Electrical Terms to Help Understand Electric Fencing
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a.c. | Alternating current as from mains power supply 110v or 220/240v 50/60Hertz. Described as alternating because the current oscillates from positive to negative and back again 60 times each second |
Amp
(Ampere) |
Amps (amperes) is a measurement of the Rate of Flow or 'Volume of Electricity'. For those who are interested; One amp is defined as 6.28 x 10 18 electrons per second. Calculation: Current = Watts divided by Volts and/or Volts divided by Ohms. The equivalent in water is Litres (Volume of water) per hr.
The electrical current that flows through a wire is measured in amps. A 100-watt bulb in your home draws a little less than one amp of current. Most home fuses and circuit breakers shut off power if the current in an individual line exceeds between 5 to 20 amps; while the maximum current that circuits in most homes can handle is between 100 and 200 amps. Power lines often carry a few thousand amps. In contrast, electronic circuits usually carry only a few milliamps (thousandths of an amp). One milliamp is the smallest current you can sense and will produce a slight buzzing feeling if it passes through your skin. |
Amp Hour
(Ampere Hour) |
The Amp Hour (Ah) is referred to frequently in our battery section. It is a measurement of the batteries capacity i.e. the volume of energy stored when fully charged. The measure determines the Amps available when discharged evenly during a 20 hour period.
Dividing the Amp Hour rating of the battery by 20 will tell you how many Amps the battery will output constantly before fully discharging. For example: An 85 Ah battery will provide a maximum 4.25 Amps constant output for 20 hours. (85 divided by 20 = 4.25). |
Circuit | A conducting path around which electrons may flow.
Electrical circuits can be complex, but at the simplest level, you always have the source of electricity (a battery, etc.), a load such as a light bulb or motor, (an animal touching your electric fence), and two wires to carry electricity between the battery and the load. Electrons move from the source, through the load and back to the source. |
Conductor | A material through which electrons will readily flow. (All metals are conductors).
Electricity will always take the shortest path to the ground. Your body is 70% water and that makes you a good conductor of electricity. For example: If a power line has fallen on a tree and you touch the tree, you become the path or 'conductor' to the ground and could get electrocuted. |
Current | It is the current and the duration and rate of its flow which causes a Shock. Increasing the voltage increases the current. Current decreases as resistance increases.
Measured in Amps |
d.c. | Direct current as from batteries. Current flows in one direction from the battery. |
Earth Rod | The stakes in the ground connected to the earth terminal. The earth rod collects the pulse. |
Electrolysis | Corrosion which occurs when different metals are connected in a wet Environment such as with electrical connections between say copper, and galvanized wires on a fence line. Avoid this by using only Galvanized wire and connectors. |
Hydraulic Analogy | This is the often used comparison of electrical circuits to a system of water pipes to explain how electricity "works".
Voltage becomes water pressure; determining the speed of flow – how fast the electrons travel through the circuit and governing the rate of... |
Impedance | Total effective resistance |
Induction | Power transfer without contact. For example, the charging of dead or neutral fence wires which run parallel to live ones. The closer the Live and neutral wires and the further the distance they travel together, the greater the amount of induced voltage. |
Insulator | A material which strongly resists the flow of electrons through it.
The rubber on an electrical cord provides an insulator for the wires. By covering the wires, the electricity cannot go through the rubber and is forced to follow the path of the wires. |
Joule | Unit of energy. One joule is one watt for one second. It is the measure Of the 'kick' of a pulse. Joules are the most important measure of the power of the energiser. |
Kilowatt | A kilowatt is a measure of electrical power equal to 1,000 watts. |
Leakage | Conduction from the live wires to earth caused by poor insulators, shorts and vegetation growth on the wires resulting in a drop in voltage. |
Live Wire | The wire connected to the energiser live terminal. The live wire must be insulated to conduct the pulse down the fence. |
Load | Any power consuming device connected to an electrical circuit. |
Ohm | Unit of resistance. One ohm is the resistance value through which one volt will maintain a current of one amp. Calculation: Ohms = Volts divided by Amps.
The ohm scale is a reverse one, i.e. Low numbers indicate heavy load, and high |
Pulse | A brief electric current or shock emitted by an energiser. Each pulse is on for about 0.0001 of a second. Pulses are spaced about a second apart. |
Resistance | Measured in ohms. The equivalent of friction in water. Calculation: Resistance = Volts divided by Amps.
When current flows through a conductor it creates heat because of resistance. Imagine Resistance as how tightly the material is holding the current. You may have noticed that the cord from an appliance can feel warm after running for a long time. That is the amperage flowing in the circuit. The more amps moving the more heat is produced. When a wire carries too many amps for its size, it becomes 'overloaded' and the insulation can melt and cause a fire or can shock you if you touch it. That's why it is always important to have the correct wire size. In relation to resistance, it is worth noting that an animal with soft feet such as a dog, has less resistance than an animal with hooves. Likewise, a person wearing Wellington boots would feel less shock than someone wearing canvas shoes. |
Short | Low resistance leakage caused by live wires touching earth return wires, steel supports or the ground resulting in a severe drop in voltage. |
Volt | Unit of electrical pressure which causes current to flow. Voltage is a measure of the rate at which electricity is moving i.e. how fast the electrons are moving through a circuit. Calculation: Voltage = Current (Amps) x Resistance (Ohms). One volt drives a current of one amp through a resistance of one ohm.
Current in a wire is driven by voltage in roughly the same way that water in your pipes is driven by pumping stations. 1000 volts Equals 1 Kv. |
Watt | Unit of power, both electrical and mechanical. The power needed to operate an electrical device. The product of voltage x current.
Power is the rate of doing work or providing heat. Power levels around a building can range from a few watts for a typical nightlight to 5,000 watts (or five kilowatts) for a large air conditioner. Motors around the home are usually rated in horsepower. One Horsepower equals 746 watts. Thus a 1.5 horsepower motor uses over 1100 watts; a half horsepower motor in a washing machine will use about 375 watts. |
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