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A hypothetical question to improve my understanding of stabilizers and power supply.

Consider a rural village where frequent low voltage issue happens.

Now, if everyone there uses stabilizers to overcome the low voltage issue -

  1. Does it give more load on the transformer which supplies electricity? Why should it have more load? V * I will be almost same, as less Voltage is compensated by more Current by stabilizer, so summation of all Voltage * Current of each house will give same load on the transformer. But possibility of main transformer burning up because of high current(from all house) caused by low voltage.
  2. Most of the stabilizers go to cut off because of extreme low voltage?
  3. What happens to a home which doesn't have stabilizer?
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    \$\begingroup\$ You seem to be assuming that when the supply voltage drops, more current somehow magically becomes available. But it's the inability to supply the required current that causes the voltage to drop so it's a completely flawed question. \$\endgroup\$
    – Finbarr
    Commented Jun 4, 2020 at 22:09

3 Answers 3

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When the demand current rises from a drop in voltage, the stabilizer increases the demand and thus causes more drop to the shared network.

But if everyone has a stabilizer, then the distribution becomes more unstable and probably unusable. Effectively, AC stabilizers are a negative incremental resistance.

It is better to regulate the source with manual or auto-taps then ensure the rated load does not drop more than 10% voltage in each distribution. Normally 5% for generation and 5% for distribution in well-designed networks worst-case.

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    \$\begingroup\$ One query: From the point of power distribution network, what makes it to provide more current to one using stabilizer? The negative incremental resistance you mentioned is because of more current stabilizer withdrawing, right, so kind of total resistance has reduced from distribution perspective? Not because it sees less resistance so giving more current. Am I correct? \$\endgroup\$
    – Sreeraj Chundayil
    Commented Jun 5, 2020 at 10:36
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    \$\begingroup\$ Yes. It's a Supply regulation error due to reduced load impedance on one load which is minor but if all users did this it would be more unstable. which contributes to the overall problem that you have. Regulation error is the inverse of Damping Factor (impedance ratio) on speakers. Negative feedback lowers both input and output impedance due to each negative feedback The better solution is to lower grid source impedance at > 50MVA sources with stabilizer (auto-tap-changer) then load stabilizers are not needed. as in all of North America \$\endgroup\$
    – D.A.S.
    Commented Jun 5, 2020 at 14:02
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These stabilisers already exist in rural villages to overcome the voltage drop due to long distance lines. In the city is not needed because they have to install enough transformers and the HV power line is always near.

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  • \$\begingroup\$ I will edit it to rural village. If enough transformers are not there. \$\endgroup\$
    – Sreeraj Chundayil
    Commented Jun 4, 2020 at 22:00
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    \$\begingroup\$ Then the answer is: They would overload the transformer, causing the black out. The home without the stabiliser would face even higher voltage drop. But in my opinion this should be caried out by the electric company, they have to provide a stable voltage. \$\endgroup\$
    – Marko Buršič
    Commented Jun 4, 2020 at 22:05
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    \$\begingroup\$ @MarkoBuršič I suspect the OP is referring to India where faked nameplate capacities by the various "electric companies" is a chronic problem. (They get paid for the nameplated capacity but choose to buy way under that and "redo" the nameplate so they still get paid for more capacity than they can actually deliver.) (And no, I had nothing to do with marking your answer down.) \$\endgroup\$
    – jonk
    Commented Jun 4, 2020 at 23:21
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Lets simplify this to one phase and pure resistive loss in the power line. Let's assume the power company hasn't line protectors which trip at certain current.

If we assume the power company outputs voltage Uo to a rural village but there's resistance R in the supplying line which causes the actual voltage in the village be Uv=Uo-IR where I=the total loading current of the village.

If everybody has a voltage stabilizer and everybody have ON certain devices which need certain total power P one can calculate What is the remaining Uv.

Substituting I=P/Uv one gets a 2nd degree equation for Uv. It has a solution if P is equal or less than (Uo^2)/(4R). In that case there's still Uv at least Uo/2 and everybody are happy except the power company who dissipates substantially power in the wire resistance. The limit case is when the dissipation in the wire resistance is as much as the power consumption of the village. That's the maximum available power to the village.

If the inhabitants demand higher power than (Uo^2)/(4R) there's no solution, the current increases, the voltage drops and finally the stabilizers stop. The voltage can be back until the stabilizers start again want too much.

Assuming pure resistance is nonsense. There's transformers and the lines itself also have capacitance and inductance. Voltage stabilizers which take more current when the voltage drops can be considered as negative resistance. The whole circuit has good chances to be an oscillator which works with the same idea as a microwave diode oscillator (=negative resistance diode in a reactive circuit). Another unreal assumption was the lack of protection devices in the distribution system. The power company cannot allow too high dissipation in their devices, so a part of the load will be dropped off.

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