Can we remove Neutral wire? Importance of Neutral wire

can we remove neutral wire to cut the long story short the answer is yes but of course that depends upon few conditions in this video you will learn in which situation you can remove neutral wire why neutral is so important and why the size of neutral conductor is smaller as compared to the other phase wires so to get all these details you need to watch the video to understand if we can remove neutral wire let's go to our distribution transformer distribution transformer is connected in delta star configuration as shown and the conductor shown by the dotted line is called as neutral conductor or simply neutral this neutral conductor carries the return current of all the three phases now let's connect load to the secondary of this transformer so i have connected 3 heaters of 100 watts each the connected load is basically a balanced load as current taken by each heater is same now the neutral will carry the sum of three return currents that is ir plus iy plus i b at first many of the people will think that the conductor required for neutral should be three times in the size than the other three conductors but we know that current of the three phase system is out of phase by 120 degree from each other and hence if we draw a waveform for this current it will look like this now if you observe the waveform carefully you will find that the sum of return current is zero at every instance how let me show you for example at instant shown here corresponding to 240 degrees current of phase b is maximum and current of phase y and b is negative 0.5 so we can write it like this now if we add all these currents we will get some of these current equals to zero and this is true for every instance therefore now we can remove the neutral conductor and this will not affect the voltage or current in the circuit it will still function as it is without any problem great why are we using neutral then let's remove neutral from everywhere because we don't need it wait let's not jump to the conclusion let's also look at the second side of the coin we can remove the neutral conductor or wire however to achieve this the load connected to the circuit must be identical the load must be balanced so in an ideal situation or in the situation where load is equal current flowing through neutral conductor is always zero in practical life this situation is not possible you will not have identical loads on each phase for three-phase loads like three-phase induction motors you don't need neutral because that is balanced you can put it in operation without any neutral wire now let's say i change the heater connected to b phase this new heater is now drawing 200 watts of power and hence my waveform will now look like this if you observe waveform carefully you will find that the sum of the return currents is no more zero that means definitely there is some return current but as we have removed the neutral conductor there is no written path for the current to flow as a result voltage imbalance in the system will occur if the load is not identical then removing neutral conductor can cause unequal voltages across the loads some phase will have lower voltage and some will have higher and hence the device receiving this high or low voltage will be under risk for example if a device is designed to operate at 230 volts maximum and suddenly it receives 350 volts well that can damage the device completely and hence we cannot or rather we should not remove the neutral wire if the load on each phase is not identical or balanced the issue is not really with the three-phase load it is with the single phase load let's say we have three different houses connected to three different phase as shown now as we have seen i can remove the neutral wire if power taken by all the houses is equal but that is not possible practically power taken by each house will be different than the other and in such case if i remove the neutral voltage imbalance will occur as a result maybe raid house will have low voltage than the normal yellow house may have high voltage than the normal and maybe blue house will have very high voltage than the normal and surely this high voltage will damage the devices connected to that house so to avoid such situation a neutral wire is must now the neutral wire need not be the same size as the other wires because neutral wire will not carry the same amount of current as other phase wires are carrying to prove it consider the waveform shown here this waveform is of the three houses which we connected to the three different phases consider the peak value of current is one ampere and which is taken by the red house let's consider this instance here current taken by the red house is 1 ampere similarly current taken by yellow house is negative 0.25 ampere and negative 0.5 ampere is taken by the blue house as we have seen current flowing through neutral wire is some of the three return currents so let's add the current of all phases so i n equals to i r plus i y plus i b and that's gonna give us i n or the current flowing through the neutral wire is 0.25 ampere so as you can see current flowing through the neutral conductor is only 0.25 amp whereas the peak value of current is 1 amp this is true for all the instances you can take any instance of the waveform and do the calculation and you will get current flowing through neutral wire is much lesser than the peak value and hence conductor size of the neutral need not be the same size of other phase conductors so i hope that answers the questions you have now let's quickly summarize this video current flowing through neutral is always zero in an ideal situation that is in situation where loads connected in all the three phases are identical we can remove neutral wire only if loads connected in all the three phases are identical removing neutral wire from system where loads are not same or identical will result in unequal voltages across the loads conductor required for neutral wire can be smaller as compared to the other phase wire as current flowing through the neutral wire will be less than the current flowing through other wires in case if you are new on this channel my name is gaurav j i post videos related to electrical engineering with easiest explanation so if you are interested in electrical engineering you can consider subscribing the channel if the video helped you do hit the like button that's all i ask that's all for this video guys i'll see you in my next one but till then keep watching keep learning [Music] you

Channel: Gaurav J - TheElectricalGuy

Views: 61,223

Keywords: theelectricalguy, gaurav j, neutral, neutral wire, remove neutral, size of neutral wire, importance of neutral, neutral conductor, purpose on neutral

Id: dRuYSd7pwSY

Length: 7min 53sec (473 seconds)

Published: Thu Jul 02 2020