RC SNUBBERS:
A simple snubber comprising a small resistor (R) in series with small capacitor(C) is often used. This combination can be used to suppres the rapid rise in voltage across a thyristor, preventing the erroneous turn-on of the thyristor; it does this by limiting the rate of rise in voltage 9dV/dt) across the thyristor to a value which will not trigger it. Snubbers are also often used to prevent arcing across the contacts of relays and switches and the electrical interference and welding/sticking of the contacts that can occur. An appropriately-designed RC snubber can be used with either DC or AC loads. This sort of snubber is commonly used with inductiveloads such as electric motors. The voltage across a capacitor cannot change instantaneously, so a decreasing transient current will flow through it for a small fraction of a second, allowing the voltage across the switch to increase more slowly when the switch is opened. While the values can be optimised for the application, a 100 ohm non-inductive resistor in series with 100 nanofarad, or larger, capacitor of appropriate voltage rating is usually effective. Determination of voltage rating can be difficult owing to the nature of transent waveforms; the actual rating can be determined only by measuring temperature rise of the capacitor. This type of snubber is oftern manufactured as a single component.
A simple snubber comprising a small resistor (R) in series with small capacitor(C) is often used. This combination can be used to suppres the rapid rise in voltage across a thyristor, preventing the erroneous turn-on of the thyristor; it does this by limiting the rate of rise in voltage 9dV/dt) across the thyristor to a value which will not trigger it. Snubbers are also often used to prevent arcing across the contacts of relays and switches and the electrical interference and welding/sticking of the contacts that can occur. An appropriately-designed RC snubber can be used with either DC or AC loads. This sort of snubber is commonly used with inductiveloads such as electric motors. The voltage across a capacitor cannot change instantaneously, so a decreasing transient current will flow through it for a small fraction of a second, allowing the voltage across the switch to increase more slowly when the switch is opened. While the values can be optimised for the application, a 100 ohm non-inductive resistor in series with 100 nanofarad, or larger, capacitor of appropriate voltage rating is usually effective. Determination of voltage rating can be difficult owing to the nature of transent waveforms; the actual rating can be determined only by measuring temperature rise of the capacitor. This type of snubber is oftern manufactured as a single component.
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