Three-phase meter power is mainly determined by the current specifications and field voltage of the three-phase meter. If it is a direct current meter, power P=I current *U voltage *3, Here we take a look at the three-phase meter can withstand how much power and how to choose the transformer multiple.  

I. Three-phase electricity meter can withstand how much power  

If the current specification of three-phase meter is 40A and the field voltage is 380V, then the power P=40A*380V*3=45600W, why should we multiply by a 3? Because this is a three-phase electricity meter,40A*380V is only the power of a phase line, so the three-phase power must be multiplied by 3. The three-phase direct electricity meter can achieve 100A at most.  

So the maximum power of the direct-in meter can only withstand 114,000W of power. If the power is higher than that, the direct-in three-phase meter cannot meet the needs. We need a mutual inductance meter.

II. How to choose the transformer multiple  

Mutual inductance meter does not limit the power, as long as the multiple of the transformer reaches, any amount of power can be used. For example, what should we do if we want to measure the power of 200,000 W? The current specification of general transformer type is 1.5(6)A, we can calculate the current first,I=P/U=200000W/380V≈  53A, Then we use the transformer to change the current into the current within the measuring range of the meter. The current range of the mutual inductance meter is generally 1.5 to 6A. If the current is changed into 5A, You need 10 times the transformer, so to measure 200,000, you only need 10 times the transformer.  

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