Calculation formula for starting time of electric energy meter

In the national standard (GB/T 17215), the starting calculation formula for an electric energy meter is given: t=(3600 × 1)/(C × P). What do these letters mean: t: starting time (seconds), which is the time it takes for the meter to start recording the amount of electricity from being powered on? C: meter constant (imp/kWh), which is the small red light flashing on your meter. Each time it flashes, it represents how much electricity is used. P: starting power (kW), usually "starting current x voltage". In other words, this formula is used to calculate how long it takes for the meter to start writing when a particularly small current (such as 0.4% Ib) is applied to it. Why is there a 3600 in the formula? Because 1 hour equals 3600 seconds. The constant C of the electric meter refers to "how many flashes per kilowatt hour of electricity used", which can be converted to "how many flashes per second", and then reversed to calculate "how many seconds it takes to flash" - that is, the start-up time.

For example, you will understand: there is an electric meter with a constant C=1000 imp/kWh (which means it will flash 1000 times per kilowatt hour). Voltage 220V, basic current 5A (which is 5 in the 5 (60) A marked on your home meter), level 1 electric energy meter. According to national standards, the starting current of a level 1 electric meter is 0.4% Ib, which is 0.4% × 5A=0.02A (20mA). The first step is to calculate the starting power. According to Ohm's law, the power calculation formula is power=voltage × current 220V × 0.02A=4.4W, which is converted to kilowatts: 4.4W=0.0044kW. The second step is to use the formula to calculate the time. C × P=1000 × 0.0044=4.4t=3600 ÷ 4.4 ≈ 818 seconds. The third step is to use the easy to understand unit of 818 seconds ÷ 60 ≈ 13 minutes and 38 seconds. That is to say, if a current as small as 20mA is applied to this meter, it should be able to read a word within 13 minutes and 38 seconds (flashing the energy meter records a pulse). Only then can it be considered qualified for startup.