Load Balancing / Voltage stabilization

[SteveInMex]

Hello, I live in Mexico, where I have a small, un-official trailer park on my property.

The property is serviced by my privately owned, 650amp transformer with two hot wires coming from the main lines on the highway. The transformer case is designed with a 3rd possible hot connection, though I don't know if the insides would accommodate it. The transformer is around 15 year old, built by a local company.

There are four RV's on the property. My RV has a 4 wire (both hots, neutral and ground) 50amp service. All the others have a 3 wire (single hot, neutral and ground) 30amp service. One of those is my work shop. Most of the year it's just me, sometimes one or rarely the two remaining trailer might be occupied. One of those has an inexpensive 30amp voltage regulator, and usually doesn't complain about low voltage.

Voltage everywhere around my location changes routinely during the day. In a previous, nearby location, I observed voltage during strong storms ranging from 60 to 160.

I've been told by local electricians that Mexico's target Voltage is 127. At my site, with only my RV occupied and a low load (a few lights, computer, monitor, etc.), in the evenings/overnight/early mornings, 132 per hot is quite routine. Later in the day, 114 is also common. Sometimes 108 per hot is the best I receive. There are occasional brown outs, and occasionally complete loss of power, often the latter is for a little as 10-30 seconds, other times for many hours of the day. (During these times I start a generator)

I have a voltage meter plugged into a 15amp receptacle on each of the hots, so I can see the voltage on both lines with a glance, any time of the day.

The power come from my transformer to an RV style Power Post which initially had 1-50amp, 1-30amp and 1-twin 15amp receptacles. There is currently a 100amp main breaker just outside the transformer chain link fence enclosure, about 170 meters away.

I've added to the post, 3 additional external breaker boxes, 2-30amp receptacles and a 15amp hard wired line for an irrigation pump (10amps max).

My issue(s)...

Much of the year I'm running a single phase, RV air conditioner (15-18,000btu). As soon as the air conditioner comes on, I observe the voltage on it's hot line dropping and the voltage on the other hot line going up

When the pre-load voltage is in the 127-135 range, the drop seems minor and isn't bothersome, but when the pre-load voltage is lower, the difference between the two numbers increases and often, the separate lines' voltage might be (approximately) 120 and 110 or 115 and 108. Other times it might be 113 and 112.

The power lines running from the main breaker are aluminum. One side has two #6 aluminum wires connected, the other side has one #4 aluminum wire (plus the neutral). Distance from the main breaker to the power post is about 170 meters. Both the main breaker at the transformer and the power post are grounded locally.

Example of bigger voltage drop... When the RV interior voltage is 113, the voltage at the main breaker (transformer cage) is about 121v or an 8 volt drop.

The air conditioner's breaker does cut out from time to time when the voltage is low and when it's low, I can 'hear' this in the air conditioner's motor.

A side note, is has been suggested that the transformer, even with it's 'old technology', having a 650amp potential (when new?) "should" have plenty of ability to deliver a higher voltage down to my power post which usually is using less than 50amps. I don't know if that is true or if it matters.

I located the manufacturer of the transformer (a local business) about this voltage drop, and have had numerous discussions about solutions, but in the end, the company owner described the transformer as having "old" technology. The transformer itself has a selector on the outside of it's case with 4 or 5 positions, and it was determined that the selector is in the best position.

He sent one of his guys here to check things with me, testing voltage simultaneously at both the main breaker and my power post, which showed a smallish drop of a few volts. We then doubled the size of the main wires (to the numbers above) from the transformer to the power post, but it didn't change the imbalance of voltage when there's a high load on one of the hots and didn't seem to change the voltage loss, though, testing was only done one day during a short period when the main breaker was outputting around 125v.

We agreed the company would build a regulator to resolve these issues, and which would installed on the input side of the power post, but after 2 years, the device never seemed to get built.

The problems are of course magnified when one or two additional RV's are occupied.

When I am here alone and running the air conditioner, I plug turn on one, sometimes two, other loads on the opposite (from the air conditioner) hot line, a 1,200watt electric heater and sometimes an additional 1,500watt heat gun, in an effort to boost the voltage to the air conditioner's line. And it works. But the draw also drops the total voltage of both lines.

It is of course, an expensive, short-term fix.

What I imagine as possible solutions... Maybe someone else will have a better idea.

1) replace the transformer with a modern, newer technology, load balancing unit, or

2) to purchase a voltage regulator/load balancing device to be installed on the input side of the power post.

I'm retired on a modest, fixed income, so materials price is a very big factor/limiter. Replacing the transformer seems out of reach.

Most of the year, the regular, maximum amperage requirement does not exceed 50-60 amps and is commonly around 30 or less, even when the air conditioner is running. During rare periods, if two additional RV units were occupied, perhaps 90 amps. (It would be easy to upgrade the main breaker as needed)

My goal is finding a way to improve the situation for as little cost as possible.

Thanks in advance for any ideas or specific product suggestions.

Steve

 

[Marvo]

I'm not a supply expert but I'll bump this thread with a few observations.

15 years old is not old as far as transformers go especially in your scenario. A new transformer may have an auto tap changer to compensate for supply voltage variations but also manual tap changing is still a thing so maybe not.

It sounds to me like you have a 'split phase' supply but you say there's an unused hot supply on the transformer so it could also be a 3 phase supply with only 2 of the phases in use. That said if you have multiple RV's on thed site I'd be surprised if it was 3-phase because it would make more sense to use all phases which would go some way towards balancing the load.

It is an unusual fault where increasing the load on one phase causes a voltage increase on the other. I would be suspecting the a poor connection on the transformer or somewhere on the source of the supply or poor grounding. The fact that rain storms have a prolonged and profound effect on the voltages also may point to poor grounding somewhere on the supply side or at the transformer or at your point of supply.

 

[SteveInMex]

It is an unusual fault where increasing the load on one phase causes a voltage increase on the other.

Marvo,

Just come in from many hours in the sun and my brain isn't working...

Yes, when I turn on the air conditioning, that line does down and the other line goes up. If I load up the 2nd line, then the air conditioned line voltage goes up.

If the lines were stable by themselves I expect that neither line would havev voltage significant voltage drop (or increase), or if the transformer would newer tech, or capable of balancing the output, both lines would remain relatively constant in their output.

I quite believe that the main lines on the highway have significant voltage changes depending on load and other circumstances, which leads me to think that my transformer is not designed to handle that variance, as the voltage is puts out changes during the day with even a light load.

I was told by a reasonably experienced source that it is possible to buy a voltage regulator designed for using two hots and would keep both hots at a near balance of voltage output. I don't know what search terms would reflect such a device, having tried voltage regulators, load balancing regulators, all I found were items far to big for my needs.

 

[Marvo]

Apologies, I mis understood.

A ferroresonant transformer might be a suitable workaround, they're simply and old school (like me). It won't fix the actual problem but it should give a constant voltage output if the supply voltage is within about 20% or where it should be. Here's a YT video that explains how they work.

Edit;
If you're going to google them they're sometimes called 'constant voltage transformers' or 'cvt's' for short.

 

[Marvo]

From a less technical and a more holistic point of view, you're in some far flung location in Mexico with few inhabitants so probably no local industry and you got an electricity supply with unstable voltage. Realistically your chances of getting the electrical supply authority to upgrade or perform significant improvements are at or are approaching zero unless you marry into or give a hefty bribe to the local mayors family. I'd suggest you'd be going in the right direction trying to find a financially viable workaround.

As I've already stated I'm not an expert in supply or in renewables but I'd suggest either the old school direction of a ferroresonant transformer on each phase of the supply or look at the new school approach of an inverter and battery setup that would isolate you from the grid supply and also give you some back up power should you need it.

 

[SteveInMex]

Yes, there's no chance of affecting main line supply voltage stability, except perhaps to make it less stable...

I have a ferroresonant ac/dc converter in the shed so I know of this term. I will look into a pair of ferroresonant transformers as an option. or maybe there's a twin unit available.

Another option, but with long-term higher costs... I could disconnect my existing transformer and have the power company hook up one of their own. I would have to pay some charges for set up, and it would probably improve local stability. Long-term, it would cost more every month.

Residential electric rates here have a 3 tier pricing structure. First level pricing is cheap but has a pretty low max kilowatt per billing cycle/use level, which if exceeded additional kilowatts are priced as tier 2, higher. If tier 2 maximums are exceeded, that pushes the consumer into a fixed, tier 3 price structure, and that price rate is meant to be oppressive.

I would almost certainly get booted to tier 3 within a couple of months and never get out.

Or, I could pay for multiple hooks ups, each RV on to it's own meter, and using a power company transformer. My personal use spit across two of those would still cost more per month than the rate I get now, having provided my own transformer.

Having my own transformer gives me a fixed lower rate regardless of consumption. This makes it economically reasonable to be running the air conditioner full-time, as well as irrigation pumps, etc. Not free be much cheaper.

And there's solar. Many, many homes here have installed setups which have them producing more than they use. They can push excess into the grid, but at that point, do not receive payment for that, only credit against future billing. In time I expect the power company will have to start paying for what they receive from this systems.

But the initial price to set up my property would quite exceeds what a new transformer would cost.

Having choices doesn't mean having a good choice (so far).

 

[SteveInMex]

Seems pretty likely that one of the folks on the professional threads knows exactly the kind of device I'm looking for. Hopfully one will notice this request!

 

[Marvo]

Replacing your transformer might not make any difference to your supply stability if the problem lies on the MV/HV supply side. If you're going to throw money at improving the actual supply you need to ascertain exactly what the problem is first and that's going to involve the type of test equipment you're nnot going to have access to or the skills to safely use it.

 

[SteveInMex]

It appears that I've found a voltage regulator (Corrector) that will handle my problem.

I've purchased and installed a ISB Sola Basic "Corrector" 4000 (made in Mexico). This company makes many different kinds of regulators for various issues, protecting a refrigerator, computer, etc..

Two series of products that I have some past experience with are the Voltage Corrector and the Voltage Regulators units, in 4000 and 8000 Va. These allow for voltage input from 85v to 147v.

The Corrector models are less expensive than the Regulator models, the difference being, the Correctors have a "variable" voltage output ranging from 102v to 129v.

The Regulator models have a fixed voltage output of 127v. (note, here in Mexico, the power company intends to supply 127v for residential use.)

Both of these devices are designed for a single hot wire/phase circuit. As indicated in my original post, I have two hot wires. It was this difference which previously had me skip past these products as possible solutions.

However, I went to Schneider Electric Guadalajara for a consultation, about an hour of investigating options. They had several suggestions of which the cheapest would have cost around $3,000 (dollars). Those weren't within my price range...

Once they understood I needed a more economical solution, they suggested I might use two of the Corrector units to solve my problem, one for each hot wire.

Considering my specific needs, I purchased a single Corrector 8000 (as a test) and installed it to the hot wire of my system which support the air conditioner in my trailer.

These units have an internal (not for customer use) adjustment which informs the Corrector if you commonly need voltage boosting or reducing.

The result in my case is, the huge voltage drop on the hot wire serving my air conditioner is now "corrected" to a safe voltage range. Over the next weeks, I will monitor the voltage on both lines and, if the second hot wire's voltage is seen as too high (or too low) I will purchase and install a second Corrector on that hot line as well.

I selected the Correct model because of it's lower price. Certainly, the Regulator model(s) would be a better choice because of the steady voltage output. I have seen individual uses of these units in several homes here in Mexico, and several more at the RV parks here.

The Corrector voltage output depends on input range. These numbers are approximate:

Input / Output
90 109
95 115
100 121
110 121
120 120
135 121

It might be interesting to consider that it would be possible to put two Correctors on the same circuit, the first would bring the voltage to a "reasonable" corrected range (high or low) and the second would use the output voltage of the first and refine the final output.

It's important to note if you might consider one of these units as suitable for your specific voltage issues... this kind of regulator can be killed if the voltage input level is at either end of the maximum input range AND your load (amps) is near the maximum ability of the Corrector. An example, if you have the 4000 model and a 25-30amp load and the input voltage is say, near/below 100v, or near/above 130v, if this condition remains for a long period the 4000Va unit would quite possibly burn up (copper coil inside), where the 8000Va unit would not.

A sustained, high load during a sustained very high or very low input voltage can damage the cooper coil. But short periods with the above input/load do not seem to work quite well.

Steve

 

[Megawatt]

Hello, I live in Mexico, where I have a small, un-official trailer park on my property.

The property is serviced by my privately owned, 650amp transformer with two hot wires coming from the main lines on the highway. The transformer case is designed with a 3rd possible hot connection, though I don't know if the insides would accommodate it. The transformer is around 15 year old, built by a local company.

There are four RV's on the property. My RV has a 4 wire (both hots, neutral and ground) 50amp service. All the others have a 3 wire (single hot, neutral and ground) 30amp service. One of those is my work shop. Most of the year it's just me, sometimes one or rarely the two remaining trailer might be occupied. One of those has an inexpensive 30amp voltage regulator, and usually doesn't complain about low voltage.

Voltage everywhere around my location changes routinely during the day. In a previous, nearby location, I observed voltage during strong storms ranging from 60 to 160.

I've been told by local electricians that Mexico's target Voltage is 127. At my site, with only my RV occupied and a low load (a few lights, computer, monitor, etc.), in the evenings/overnight/early mornings, 132 per hot is quite routine. Later in the day, 114 is also common. Sometimes 108 per hot is the best I receive. There are occasional brown outs, and occasionally complete loss of power, often the latter is for a little as 10-30 seconds, other times for many hours of the day. (During these times I start a generator)

I have a voltage meter plugged into a 15amp receptacle on each of the hots, so I can see the voltage on both lines with a glance, any time of the day.

The power come from my transformer to an RV style Power Post which initially had 1-50amp, 1-30amp and 1-twin 15amp receptacles. There is currently a 100amp main breaker just outside the transformer chain link fence enclosure, about 170 meters away.

I've added to the post, 3 additional external breaker boxes, 2-30amp receptacles and a 15amp hard wired line for an irrigation pump (10amps max).

My issue(s)...

Much of the year I'm running a single phase, RV air conditioner (15-18,000btu). As soon as the air conditioner comes on, I observe the voltage on it's hot line dropping and the voltage on the other hot line going up

When the pre-load voltage is in the 127-135 range, the drop seems minor and isn't bothersome, but when the pre-load voltage is lower, the difference between the two numbers increases and often, the separate lines' voltage might be (approximately) 120 and 110 or 115 and 108. Other times it might be 113 and 112.

The power lines running from the main breaker are aluminum. One side has two #6 aluminum wires connected, the other side has one #4 aluminum wire (plus the neutral). Distance from the main breaker to the power post is about 170 meters. Both the main breaker at the transformer and the power post are grounded locally.

Example of bigger voltage drop... When the RV interior voltage is 113, the voltage at the main breaker (transformer cage) is about 121v or an 8 volt drop.

The air conditioner's breaker does cut out from time to time when the voltage is low and when it's low, I can 'hear' this in the air conditioner's motor.

A side note, is has been suggested that the transformer, even with it's 'old technology', having a 650amp potential (when new?) "should" have plenty of ability to deliver a higher voltage down to my power post which usually is using less than 50amps. I don't know if that is true or if it matters.

I located the manufacturer of the transformer (a local business) about this voltage drop, and have had numerous discussions about solutions, but in the end, the company owner described the transformer as having "old" technology. The transformer itself has a selector on the outside of it's case with 4 or 5 positions, and it was determined that the selector is in the best position.

He sent one of his guys here to check things with me, testing voltage simultaneously at both the main breaker and my power post, which showed a smallish drop of a few volts. We then doubled the size of the main wires (to the numbers above) from the transformer to the power post, but it didn't change the imbalance of voltage when there's a high load on one of the hots and didn't seem to change the voltage loss, though, testing was only done one day during a short period when the main breaker was outputting around 125v.

We agreed the company would build a regulator to resolve these issues, and which would installed on the input side of the power post, but after 2 years, the device never seemed to get built.

The problems are of course magnified when one or two additional RV's are occupied.

When I am here alone and running the air conditioner, I plug turn on one, sometimes two, other loads on the opposite (from the air conditioner) hot line, a 1,200watt electric heater and sometimes an additional 1,500watt heat gun, in an effort to boost the voltage to the air conditioner's line. And it works. But the draw also drops the total voltage of both lines.

It is of course, an expensive, short-term fix.

What I imagine as possible solutions... Maybe someone else will have a better idea.

1) replace the transformer with a modern, newer technology, load balancing unit, or

2) to purchase a voltage regulator/load balancing device to be installed on the input side of the power post.

I'm retired on a modest, fixed income, so materials price is a very big factor/limiter. Replacing the transformer seems out of reach.

Most of the year, the regular, maximum amperage requirement does not exceed 50-60 amps and is commonly around 30 or less, even when the air conditioner is running. During rare periods, if two additional RV units were occupied, perhaps 90 amps. (It would be easy to upgrade the main breaker as needed)

My goal is finding a way to improve the situation for as little cost as possible.

Thanks in advance for any ideas or specific product suggestions.

Steve

I believe that if some how can go up on your wire size from the transformer to your place it would make a huge difference in your voltage readings. The lower the voltage the more current that your loads pull.