Accurate wattmeter for measure power loss in feromagnetic controlled AVR

Electronic wattmeters excel in very small (up to negligible) own consumption. The basiccomponents of these devices is the multiplier - a circuit whose output voltage is proportional to the product of input voltage. Wattmeter is a device that contains two coils, one of which is the current coil voltage and the second coil. Current coil is connected in series with the measured electrical circuit and the voltage measuredparallel to the coil circuit. Current flowing through the coil current causes a magnetic field is proportional to the current flowing through the phase shift and. Electromagnetic fields of both coils influence each other in case of measurements in a DC circuit, the resultingdeflection proportional to both voltage and current. When measured in AC electrical powercircuits can be determined using the effective values of current and voltage, and their mutualphase shift. A magnetic induction B can be determined using mean values. An analog multiplier are circuits, that are realized multiplication of two analog signals. They can be made by suitable connection (according to function) discreet parts. Nowadays there are integrated circuits in advance function, whose internal structure is made by complex of circuits with operating ampfliers and other circuits. These circuits have a very high accuracy of arithmetic operation which is mostly better than 1%. The analog multiplier are used in situation, when we need realize multiplication, division, exponentation, square root extraction and logarithmic calculation of analog signals