November 18, 2015

Electric Fence Charger / Energizer Circuit and how it operates | Gallagher Electric Fencing

Electric fence energizer is a device converting power to high voltage pulse shock, moderrn electric fence energizer uses a capacitor to store energy, which decides the distance the electric fence energizer can power. Engineer uses controlled circuit to charge the capacitor, then uses a thyristor to to discharge the stored energy through an isolated transformer , which transform voltage of the capacitor to very high output voltage. One of the output terminal conducts the ground rod , another conducts the fence. the power can be mains or battery, the pulse high voltage is thousands of volts, the period of the pulse is less than 1Hz for safety consideration

Source powered electric fence

The source to power the electric fence energizer depends on the condition it applies. Dry battery, acid-sealed battery, mains, solar and wind source, all is OK.
when the mains is available, people usually use mains to power the fence energizer, it is more cost efficient. The voltage of the mains can be 100volts in Japan, or 120 volts in America or 230volts in European. When use mains, for safety consideration, it is very strictly constructed, use isolated transformer to insulate the fence circuit from the mains. So the fence pulse voltage is insulated from the mains, it is safe for touch. International standards have very strict requirement on how to construct the mains fence energizer, so just use the CE marked or UL marked mains energizers, or you will have potential risks. Just buy from reliable and experienced company for your mains fencer.
When there is no utility available, battery is a normal choice. Lots of electric fence energizer company provide battery energizer. Depends on the size and location your perimeter is. Dry battery or big capacitance acid-sealed battery electric fence energizer you can choose. For pet or small animal control, portable fence normally used, the size of the fence is short, and the location often moved, so use a dry battery electric fence energizer will help a lot. The dry battery energizer can not power too long time, normally less than one month, it is OK for lots of pet , temporary electric fencing often help host a lot, and dry battery is available in lots of store, so it is a convenience choice. Lots of customer use big size acid-sealed battery also, The acid-sealed battery is chargeable, and the size can be up to 100AH, it is portable, and can power big storage energy energizer, so it is for professional customer, who has big farm or perimeter to fence. for lots of place, there is no utility, so charging is a big problem for lots of installer. People now use solar panel to charge the battery instead of utility, it is flexible, more and more people use it to charge their battery. If the power of the fence energizer is small, people use solar panel to charge the battery directly, but for big fencer, the solar panel need a controller to control the charge voltage, because the solar panel have it own characteristic, it have own MPP (Maximum Power Point) output, if it don’t work at its MPP, it will loss lots of energy , and it can not output all energy it can convert, cause energy loss and money loss, so we need a MPPT controller to help the solar panel output its full energy, the acid-sealed battery lifetime is sensitive for temperature, if charge voltage is wrong, it will decrease the lifetime of the battery, so when charge the battery, we need a temperature compensation.

Charge circuit

The charge circuit convert the source into a stable voltage on the storage capacitor, the charge method use art PWM method, the PWM is a commonly used technique for controlling power to inertial electrical devices, made practical by modern electronic power switches. The main advantage of PWM is that power loss in the switching devices is very low, so will help to save lots of energy, especially for battery electric fence energizer. The power consumption is a key issue to evaluation the electric fence energizer.

Isolated transformer

Isolated transformer transfer the voltage on the storage capacitor to high output voltage, the isolated transformer is a very key component for a energizer, lots of article and standards talk a lot about the construction, carefully design can make low impedance electric fence energizer. Low impedance means you can power longer distance, and can save more invest on electric fencing, lots of company mark their energizer as low impedance, it make people confused, you’d better ask the data of energizer under 500 ohms load to evaluate, for a low impedance fence energizer, the isolated transformer can transfer more energy to the output, have less self loss, so the output under 500 ohms have stronger power, normally the voltage is also higher, lots of manufacturer have data on web, so right now, it is easy to judge which is low impedance and which is not, it is a fast way to choose a good electric fence energizer.

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