# Do the line voltages (R, Y, B) remain the same in a 3 phase system?

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#### Deexith Hasan

does line voltages (R,Y,B) remains the same in 3 phase system ?

does line voltages (R,Y,B) remains the same in 3 phase system ? so that i can measure one line voltage as ref for voltage stabilizer...

Re: does line voltages (R,Y,B) remains the same in 3 phase system ?

In theory yes, in practice no. If you are ONLY using three phases, and are measuring the voltage between say R and Y you are probably safe to do as you propose but if it's a four wire system with a neutral wire as well ('Y' rather than delta configuration) and you are measuring R-N, Y-N or B-N you might have to take into consideration that different loads on the phases cause voltage differences due to wiring resistance and possibly inductance.

Brian.

Re: does line voltages (R,Y,B) remains the same in 3 phase system ?

is it normal to build a voltage stablizer based on measuring the one phase with neutral...my circuit is not a voltage stablizer its just an voltage regulator that allows (210-250) voltage range ?????

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my input voltage is 50hz... according to sampling theorem samples should be taken twice the original frequency....i used adc of mcu to measure input voltage periodically at 10ms...is this normal......my frnd told me to use op-amp as comparator to measure the input........

which one is faster op-amp or mcu

Re: does line voltages (R,Y,B) remains the same in 3 phase system ?

An op-amp wont measure voltage, you still need the ADC. The sampling rule is it must be AT LEAST twice the original frequency (Nyquist limit) but faster sampling will give better results. Please take into account the rate at which you can accept fluctuations in voltage. If they are likely to change relatively slowly (no more than say every 250mS) it might be easier to convert the AC to DC so it's easier to measure. It would let you read a single figure for the voltage instead of sampling the waveform and complex math.

Brian.

• Deexith Hasan

### Deexith Hasan

Points: 2
Re: does line voltages (R,Y,B) remains the same in 3 phase system ?

You have to measure each phase and regulate as an individual. Accuracy and speed of response is not what is required, robustness and safety is. Can the kit with stand a lightning strike?, can it with stand a full on short on its output, is it protected against a slight current overload for a long time (over heating).
Frank

• Deexith Hasan

Points: 2