| 摘要 |
<p>The ivention relates to a device for protection against short-circuit and overvoltage, for low power electric energy receivers (220Vx40A=8800W max). According to the invention, the device consists of a measuring circuit made with a micro-controller (U2) and Hall current transducer (T), of a power circuit made with a triac (Q1) and a supplying circuit which provides a supply voltage, a voltage to be measured and a voltage for detecting the alternance passing through zero, consisting of a transformer (T1) with median plug. The invention shows the following advantages: high decoupling rate (maximum 10 ms), the shortcircuit current may be adjusted with precision, high rate of reaction at network voltage increase, the precision adjustment of the threshold overvoltage, reduced thermal dissipation; in the case of a short-circuit, it provides the protection of the electromagnetic environment, ease in exploitation and low cost. All these advantages are due to the fact that an overcurrent is detected very quickly (a few instructions, consequently under 1 ms) and there are not sent priming impulses towards the triac (Q1) any more. The flexibility of this device, due to the use of the micro-controller (U2), leads to the possibility of implementing other useful functions, such as the data transmission at distance.</p> |
