08-02-2013, 12:20 PM
MINI PROJECT – FIRST REVIEW Lightning surge Protector with Instant remedy
1FIRST REVIEW.pptx (Size: 578.21 KB / Downloads: 39)
OBJECTIVELIGHTNING SURGE PROTECTOR
A surge protector (or surge suppressor) is an appliance designed to protect electrical devices from voltage spikes.
A surge protector attempts to limit the voltage supplied to an electric device by either blocking or by shorting to ground any unwanted voltages above a safe threshold.
It shields computer and other electronic devices from surges in electrical power, or transient voltage, that flow from the power supply.
GAS DISCHARGE TUBE
A gas discharge tube (GDT) is a sealed glass-enclosed device containing a special gas mixture trapped between two electrodes, which conducts electric current after becoming ionized by a high voltage spike.
GDTs create an effective short circuit when triggered, so that if any electrical energy (spike, signal, or power) is present, the GDT will short this.
Once triggered, a GDT will continue conducting (called follow-on current) until all electric current sufficiently diminishes, and the gas discharge quenches.
Because of their high current handling capability, GDTs can also be used to protect power lines
VOLTAGE DEPENDENT RESISTOR
Varistors are often used to protect circuits against excessive transient voltages by incorporating them into the circuit in such a way that, when triggered, they will shunt the current created by the high voltage away from sensitive components.
Important parameters are the varistor's energy rating in joules, operating voltage, response time, maximum current, and breakdown (clamping) voltage.
It has a high resistance at low voltages and a low resistance at high voltages.
WORKING
Lightning surge protector protects the electronic devices from millions of voltages.
Normally no current flows through GDT and VDR current starts to flow through these components when voltage between the terminals is higher than the sum of voltage rating of GDT and VDR (250v and 16A).
If the flowing current is more than the specified value of the main self resettable fuse,the fuse will break and circuit will be protected
After the circuit is normal the fuse resets and continue its function.