Application Notes

AN-1159 Accurate Mains Frequency Monitor with Calibration

An AC power mains utility frequency is typically either 50Hz or 60Hz. The frequency variation is normally restricted to about +/- 1% in most countries. Variation occurs usually because of varying load on the grid; a higher load causes the frequency to drop and vice versa. The importance of monitoring power frequency is especially important when a local minigrid is set up – such as with solar-powered or wind-powered installations. The inverter in such cases must shoulder the responsibility of monitoring the output power quality.

In industrial setups that use equipment such as induction motors, it is important to maintain the proper frequency because the speed of an induction motor is a function of the frequency. More elaborate and sensitive setups may use AC drives to maintain the motor speed, but in many situations the motor may be directly connected to the power source without a drive, in which case variations in power frequency directly impact the motor speed.

In this application note we show how to use a Silego GreenPAK SLG46620V and a few external components to design a frequency deviation monitor that signals an alert if the frequency deviates by a specified margin.



Accurate, Mains, Frequency, Monitor, Calibration, ACMP, Schottky, Diode

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