﻿ How to measure current intensity?

# By what device to measure current intensity?

In the course of work the electrician often should make measurements it: tension, resistance, insulation resistance. There is one more size - it is current intensity. How to measure it, and the speech in this small article will go.

The ampermeter - the device by means of which it is possible to measure current intensity.

First, current intensity is measured by the device which is called – the ampermeter. For measurement in chains of constant and alternating-current different measuring apparatuses are used. On the ampermeter scale for alternating current designation – "is put ?  And", for
constant "– And".

For strain measurement voltmeters are connected in parallel, and ampermeters - is consecutive. That is the chain needs to be broken off in the convenient place and there to connect the ampermeter. What tension in the chain - 127B, 220B or 380B - does not matter, similarly and in direct-current circuits. It as for measurement of current the separate device (ampermeter).

It is possible to measure current size also by the tester (pointer). It is possible to measure by these devices both constant, and alternating current, having installed the corresponding switch by sight of current ( ? And or – And).

In alternating current circuits measurements can be performed clamp-on ammeters, this method is convenient that measurements are performed in the contactless way. Just it is necessary to clasp the conductor with the device magnetic conductor. In direct-current circuits such measurements are not performed.

All these measurements are necessary for specialists to electricians in daily work. For example, knowing the consumed current, it is possible to calculate unit power by the formula

Р = UI

P - power (W), U – tension (V), I – current intensity (And). Let's give the example: the three-phase electric motor consumes 11A on each phase - 11A x 220B = 2420 W - from calculations it is possible to determine power. It is the standard of 7.5 kW.