Current in an electrical circuit is its key parameter. It defines operability of the device. It needs to be measured to understand in what mode any given element of the electric circuit works.
Instruction
1. Study specifications of the device which you investigate. There nominal values of operating modes are specified. According to it choose the measuring device and measurement range. The following devices are used to measurement of current: ampermeters, milliamperemeters, microampermeters. In the simplest case testers – avometra, multimeters, etc. can be applied. Set the mode of direct or alternating current.
2. Before measurement of current take preliminary voltage measurements in control points of a chain. Make sure that they are close to nominal and only after that start measurement of current. Otherwise the ampermeter can fail.
3. It is possible to measure current only at the working device. For this purpose break off the studied chain so that after measurements it was possible to restore it easily. Turn on the measuring device in a rupture of a chain. It is necessary to observe polarity if you measure a direct current. On the measuring device the polarity is specified always – pay attention to designations. It is impossible to measure current in a chain without loading as this current is short circuit current, and it will put both the measuring device, and a source of current out of action. Regardless of that, or variable you investigate a direct current, connection has to be consecutive and the measuring device turns on in a gap.
4. After the rupture of a chain switched on the measuring device, the device which you investigate, transfer to an operating mode. The received measurements of current are used for setup of the device or the site of its chain. The beginning of measurements should be spent, install the ampermeter in the mode taking a working interval of currents of the explored site of a chain with a stock no more than 50% of optimum value of current. Otherwise the internal resistance of the measuring device can lead to failure of an operating mode in the explored site of a chain. After measurements restore a chain.