What is a shortcut resistor?
Shunt Resistor is an accurate device used to measure current in the electrical circuit. Also known as a current short circuit or AMMER shortcut, it works by measuring the voltage decrease through the known resistance. Ohm's law states that v = i x r or solutions for i, i = v / r, where the current is, V is voltage and r is resistance. If the resistance is known and the voltage drop is measured, the current may be determined.
Shunt resistors are used to measure currents that would potentially damage the ammeter. This could be the result of the size of the current passing through the circuit or the possibility of current spikes. They usually have a small, well -defined resistance so that it does not affect the current it measures. Shunt the resistor usually looks different from a normal resistor that has two large terminals with one or more metal strips that connects them. The resistance of the metal is inversely proportional to its cross -sectional surface, so the more strips the resistor zhuntum is, the lower its resistance. This measurement is not accurate because it relies on the resistance is strict and constant 0.001 Ohm. From severalThis is not the case.
First, the resistance of the device itself has a span of error. While the ideal zunt resistor in the above example would have exactly 0.001 Ohm, in fact, there is a span of error called resistance accuracy. Assuming it is +/- 0.25 percent, it would mean that the measured current is between 19.95 and 20.05 Ohms (+/- 0.0025 * 20 = +/- 0.05).
Second, the current passing through the resistor produces heat. Heat changes actual short -circuit resistance. How many devices are determined by a drift of the device, usually measured in parts per mille (PPM) to the level of temperature change. For the resistor in the above example, provided 30 ppm per temperature change and temperature change would mean that the measured current is between 19.988 and 20.012 ohms (+/- 30 ppm * 20 = +/- 0.012).
In addition to the accuracy of resistance and resistance drift, short -circuit resistors are also characterized by current evaluation and performance evaluation.The current evaluation is the maximum amount of current that can go through the short circuit without damaging it. This current generates heat, which in turn affects the short -circuit resistance. The performance evaluation is the maximum amount of current that can continuously pass through the short circuit without damaging or adversely affecting its resistance. Generally, this is 2 / 3 its current evaluation.