Electric fences are designed to create an electrical circuit when touched by a person or animal. A component called a power energizer converts power into a brief high voltage pulse. One terminal of the power energizer releases an electrical pulse along a connected bare wire about once per second. Another terminal is connected to a metal rod implanted in the earth, called a ground or earth rod. A person or animal touching both the wire and the earth during a pulse will complete an electrical circuit and will conduct the pulse, causing an electric shock. The effects of the shock depend upon the voltage, the energy of the pulse, the degree of contact between the recipient and the fence and ground and the route of the current through the body; it can range from barely noticeable to uncomfortable, painful or even lethal.
Garage & Gate Motors
The typical electric garage door opener consists of a power unit that contains the electric motor. The power unit attaches to a track. A trolley connected to an arm that attaches to the top of the garage door slides back and forth on the track, thus opening and closing the garage door. The trolley is pulled along the track by a chain, belt, or screw that turns when the motor is operated. A quick-release mechanism is attached to the trolley to allow the garage door to be disconnected from the opener for manual operation during a power failure or in case of emergency. Limit switches on the power unit control the distance the garage door opens and closes once the motor receives a signal from the remote control or wall push button to operate the door. The entire assembly hangs above the garage door. The power unit hangs from the ceiling and is located towards the rear of the garage. The end of the track on the opposite end of the power unit attaches to a header bracket that is attached to the header wall above the garage door. The power head is usually supported by punched angle iron. Recently another type of opener, known as the jackshaft opener, has become more popular. This style of opener was used frequently on commercial doors but in recent years has been adapted for residential use. This style of opener consists of a motor that attaches to the side of the torsion rod and moves the door up and down by simply spinning the rod. These openers need a few extra components to function safely for residential use. These include a cable tension monitor, to detect when a cable is broken, and a separate locking mechanism to lock the door when it is fully closed. These have the advantage that they free up ceiling space that an ordinary opener and rail would occupy. These also have the disadvantage that the door must have a torsion rod to attach the motor to. Types of garage door openers: There are five types of garage door openers. Chain drive, belt drive, screw drive, direct drive, and jackshaft.
- Chain drive openers have a chain (similar to a bicycle’s) that connects the trolley to the motor.
- Belt drive openers use a rubber belt in place of a chain.
- Screw drive openers have a long screw inside the track. The trolley connects to this screw.
- Direct Drive openers have the motor installed inside the trolley and use a gear wheel to guide the trolley along a fixed chain.
- Jackshaft openers mount on the wall at either end of the torsion bar.
The most popular electric gates for residential properties are swing gates, but these are not the only option available. Articulated Articulated gate openers can be used for gates with wide posts allowing opening in small spaces. An easy system for DIY installers as they are simple to install but not as aesthetically pleasing as other motor designs. Also known as Crank arm operators, they are the main type of automation system sold in France, where low aluminium gates are often used. Underground Under-gate Jack operators usually control the gate by directly moving the pivot point of each gate leaf. This makes the unit ideal cosmetically and also allows for up to 180 degrees of leaf swing as required. However controlling the pivot point of the gate, is like opening a door by twisting the hinge, and as so is very difficult due to the loads needed at that point. This is highlighted with snap, as the gate has to change direct, as soon as it can. For this reason they are recommend as only suitable for ‘Domestic’ systems in a low risk of abuse environment. Another major consideration with the use of under-gate units is that of water immersion/ingress and warranty voidance. If the water table is high or the drainage of the unit’s foundation box inadequate throughout the systems life, then water ingress and unit failure is increased. Ram or link arm units are usually simpler to install and maintain, they are visible to otherwise ignorant abuse and as they fix down along each gate leaf, they also have an obvious and sometimes major, mechanical advantage over Jacks. Therefore, Rams are far more suitable on Multi-user & commercial systems. Also the manual release is always above ground, making it often more user friendly in operation. Sliding If space is an issue or the driveway behind the gates is on a steep incline, a better option would be a sliding gate. Sliding gates are also very popular in a commercial environment. Sliding gates are also used for cantillever gate systems.
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