For measurement of current contact and contactless devices are used. The second possess smaller sensitivity, but allow to do without intervention in a chain in which measurement is performed.
Instruction
1. Micro and milliamermetra are intended for measurement of a direct current. For this purpose cut off power a chain, break off it then include in it, observing polarity, the measuring device. Again include loading food then read instrument readings. After that cut off power a chain, switch-off the device, and then restore connection.
2. At measurement of the currents making units, tens and hundreds of amperes parallel to micro or to the milliamperemeter it is necessary to connect the shunt. The last has to be calculated on work together with the device of the applied type. It is important to turn on the shunt in a rupture of the chain which is (also previously cut off power), and to attach only to it thin wires the device, but not on the contrary. Recognize by marking of the shunt by what coefficient it is necessary to increase indications.
3. Multipurpose devices (multimeters and testers) and also multilimit ampermeters contain the built-in shunts chosen by the switch. In addition, they are equipped with rectifiers and therefore allow to measure also alternating currents. Cut off power a chain, choose a limit and a sort of current by means of the switch then turn on the device in a rupture of a chain. The analog tester or the ampermeter demands at measurement of a direct current of respect for polarity. Cut off power a chain before each switching of limits. Determine by position of the switch on what scale to read out indications and also by what coefficient to multiply it.
4. Inductive contactless ampermeters (klampmetra, current pincers) allow to measure only alternating current with a force not less than several amperes. To use such device, carefully not to concern the bared conductors, place one wire between sponges then close them. If necessary use wiring rubber gloves. Do not clamp at once two wires in which current proceeds in an antiphase (for example, an electric cord entirely) - instrument readings will be equal to zero.
5. Current pincers with Hall's sensor differ from described above by the fact that are sensitive also to constant magnetic field. It gives the chance to measure in the contactless way not only a variable, but also direct current. When using of such device choose not only a limit, but also a current sort, otherwise indications will not be true.