Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Power Theft Prevention

Power Theft Prevention

Power Theft Prevention

Hi guys.
As part of my infrastructure to prevent power theft by customers connected to our power network, I want to install 50Hz to 5Hz frequency converter at my 11kV/400V main power distribution transformer transformer and also a 5Hz to 50Hz converter at the customer's premises integrated with their meter at 400/230V. 
When power is received from the 11kV grid and transformed from 11kV to 400V, the frequency is also transformed from 50Hz to 5Hz. When the power gets to the consumer's premises, it is transformed from 5Hz to 50Hz by a 5Hz/50Hz frequency/frequency converter.
Thus, if customer bypasses the meter at their end, it will automatically bypass the 5Hz to 50Hz converter which will cause their equipment to malfunction because power supply will be at 5Hz which is not suitable for any of the equipment/loads. This is expected prevent power theft. 
A sketch of the conceptual circuit configuration is attached.

Please, let me know if this has been realized before, the size of the Frequency/Frequency Converter or complete kWH Meter unit with the converter integrated in the same package,and cost. Basic specifications - 50Hz/5Hz at 400V, 3-phase and 5Hz/50Hz, at 400V & 230V (single & 3 phase)of various amperage for tariffing kWH meters with the frequency/frequency converters installed.

Grateful you treat as urgent.

Best Regards, Anthony

RE: Power Theft Prevention

To be blunt, it's a stupid idea.

RE: Power Theft Prevention

If you're going to go to that much trouble, install metering at each transformer and ocmpare it to the meters periodically. If they don't match up (within a reasonable amount of losses), you've got theft.

But otherwise I agree with LionelHutz. Expensive, wasteful, lossy, not very good idea.

RE: Power Theft Prevention

As the power provider, you will be introducing about 6% constant losses across those inverters, which will NOT be seen by the user. So those losses come out of your revenue, 24/7/365. On the other hand, you may be underestimating the physical size and extreme cost of those inverters, not to mention that the above mentioned losses will be heat, which must be dealt with.

As was said (and what other utilities are doing with “smart” meters now), measure a group of users, then measure each one with their meters and add those together. The two values should match. If they don’t, one (or more) of the meters in that group is bypassed. If the group is 20 users, you only need to send out an investigator to those 20 locations. If you are not using smart metering, the cost to implement that will be a FRACTION of the capital expenditure of that inverter scheme.

" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

RE: Power Theft Prevention

Thony is coming up as Nigeria so the issue is a bit more understandable.

Is there an issue with higher ( or maybe lower) transmission line losses at low frequency?
Or other physical issues with transformers?
Or do you just plan to do this on the transmission line itself.
what are the losses in the frequency convertors?

But this would only impact anything with a motor surely? and I'm pretty sure there would quickly be a lucrative trade in Chinese frequency convertors...

Unless tis is a simple one consumer power line, then it seems expensive and inefficient.

But maybe if the thefts are 50% of your transmission amount then it's worth a try?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Power Theft Prevention

Compared to the cost of the inverters, it may be cheaper to just give the customer free power.

I spent a few years as the system engineer for a small utility in a culture where power theft was rife.
I have seen quite a few schemes to steal power.
I can't think of a single power theft method that would stopped with your method as you think it will. (And I have seen quite a few schemes.)

Put a revenue meter on each transformer, and compare to the sum of the meter readings of the clients on that transformer.
Have your IT person add a routine to the billing software that will flag any discrepancy.

Ohm's law
Not just a good idea;
It's the LAW!

RE: Power Theft Prevention

Yes electricity theft can be a thorny issue. One idea is to place a second meter at the transformer.
Also insist on meter readers to look at the meters, as this is frequently your main source of see who may be stealing electricity. Also don't give the meter readers the previous meter read, so they don't have any idea what this was (it becomes more difficult to fudge the numbers of the meter read).

Maybe just as dumb but cheaper is don't step the voltage down to the final voltage at the pole top, but have it higher, and do the last bit at the customer. Transformers are cheaper than frequency converters.

Another method may be actuality prosecution of a few of the energy diverters in a very public way with very large fines. And refuse to reconnect service until the fines are paid. Make an example out of a few to get the message across.
If that person is unknown make a large blackout in the area (if you can) until that person is known. Offer large rewards for information, that usually get information flowing.

That said, we don't have the energy theft culture here, so we don't see as many problems.

RE: Power Theft Prevention

We had one instance a a fellow who had never been suspected of stealing power until he died, and the next meter read was less than the previous read.
He had an arrangement that let him run the meter backwards for one week every month.
That effectively cut his consumption in half.
The reverse connection was in effect when he died and the meter just kept running backwards.
That worked with the old electro-mechanical meters but won't work with the new digital meters.
The digital meters save the incoming power in one register and save the reverse power in another register.
The meter then reports the sum of the registers.

Ohm's law
Not just a good idea;
It's the LAW!

RE: Power Theft Prevention

At a former utility employer we used to install what we called 'spy transformers' which was a pole top transformer with the internals removed and a meter installed inside. We'd install them on a pole and connect them to the service drop of a suspected diversion (theft). The night troubleman would go out the same night as the monthly meter read for the diversion, take the cover off the transformer, and read the 'spy' meter. We'd then compare the results of the house meter and spy meter.

We once caught the owner of a fairly large electrical contractor with a tap on the underground service drop between the riser and the meter on the house. He eventually lost his license (and company) for a few $1,000 of free electricity.

Not sure why he didn't notice the pole-top transformer that had the secondary connected to the primary bushings and the transformer secondary connected to his service drop!!!!!

BTW: It was a disgruntled employee who turned him in!!!

RE: Power Theft Prevention

Even if frequency converters were not cost prohibitive, the proposed solution seems easily bypassed by customers also installing a frequency converters on the bypass.

As a quick way to estimate the enormous costs for this, every house would need the equivalent of two island capable pure sign wave inverters. That would be the equivalent to several years of power costs for my house.

Although AMI is obviously useful for reactive analysis once theft is suspected in a specific location, I am curious if any utilities have been successful at using differential AMI meter summation to pre-emptively identify residential theft. Other than large commercial/industrial customers, I rarely have less than 100 customers downstream of a 12 kV metering location. Having 1 out of 100 customers stealing power is about the same as having 1% error in metering values. For circuit level analysis, the line, transformer, and service conductor losses are a couple of percent.

RE: Power Theft Prevention

Thanks guys. Very helpful feedback. Super stars you are.

RE: Power Theft Prevention

It seems to me an incredibly expensive and inefficient solution. The losses for frequency converters of this type are significant; I would say that for single-phase units integrated into the meter, you would have a 5% loss. For the larger unit downstream of the transformer secondary, you might consider an additional 4% loss.

Furthermore, the low-frequency BT circuit breakers in your 5 Hz network cannot be "normal" off-the-shelf breakers; they will need to be specially tested for operation at such a low frequency.

The aspects related to the management of these frequency converters integrated into the meters also seem incredibly complicated to me. When I think about the spaces where power meters are currently installed (wall niches, outdoor panels), they do not seem suitable for accommodating an electronic converter (which must dissipate significant losses) while ensuring reliability.

Wouldn't it be more advisable to follow the best practices adopted by almost all modern utilities to prevent theft? For example, as already suggested by others users, real-time power measurement on the transformer secondary, on the distribution panels of the BT network, and on the users to identify any imbalances indicative of energy theft.

Si duri puer ingeni videtur,
preconem facias vel architectum.

RE: Power Theft Prevention

Having just remembering it, meter seals. Most utilities here use a plastic use once seal, that must be broken to open it. It is plastic with a wire clip. It does not take much to cut the wire, or break the devise, but it is very apparent when broken. I think many trucking companies use these also. These each have a unique number, so it can also be told if they are replaced.
That said, my old company once used lead seals on a wire loop.

This is all good, but having a trusted person put there eyes on the meter is also important. Automatic meter reading is not the be all, end all. Also, meter readers can be bribed, so by not giving them the previous meter read, they are less likely to be able to fudge the numbers.

Sort of the dumbest idea we have is to pay the person handling your money, the least amount. The meter reader, clerk, cashier, etc.

RE: Power Theft Prevention

The plastic (and older lead) seals can be easily tampered with. I won't say how, but it's possible (although it's still detectable if you know what you are looking for). This was one of the driving forces behind moving to "smart" meters.

"Spy transformers"... I love it!

Conspiracy nuts will have a field day with that one.

" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

RE: Power Theft Prevention

That seal prevents you from removing the meter.
It is on the ring that holds the meter in place on the socket.
Some thieves open the meter and turn down the calibration all the way so that the meter runs slow.
To do that, a special seal must be broken. It is a one use seal. It is intentionally fragile and cannot be removed without breaking.
The supply is very tightly controlled.
I was the system engineer for a small island utility with about 5000 meters.
The supplier that sold us our meters had the seals, but we were not a big enough utility to be allowed to purchase replacement seals.

Quote (Jeff)

The plastic (and older lead) seals can be easily tampered with.
I won't say either, Jeff. grin

Ohm's law
Not just a good idea;
It's the LAW!

RE: Power Theft Prevention

The meter dept. used to pay out $50 to any company person who found a diversion. The meter dept. supervisor would have to confirm it before you got the paid. The meter readers were always finding upside-down meters back in the day especially when the company would mix up the 'read day' so it wouldn't be at the same time of the month.

I once got 50 bucks for a meter socket that had 1/2" copper pipe with the ends crimped and used as jumpers in the meter jaws. It must have been a very brave soul (or very dumb/lucky) who installed those jumpers!

RE: Power Theft Prevention

Quote (JJ Roy)

The meter readers were always finding upside-down meters back in the day
The newer digital meters will meter accurately even when installed upside down.
The meter for the office of our utility was on the front of the building on a main thoroughfare.
This was on a small island with no roads or vehicles, only sidewalks and push carts.
We intentionally installed the digital meter for the office upside down to make the point to the public that that dodge no longer worked.
Some years back we had a similar thread going and it was developing into a tutorial on how to steal power.
The site management deleted much of the thread for that reason.
And that is why I don't share here a number of creating methods that I have encountered that were used to steal power.
Ps: I like the $50 bounty idea. That one is new to me and I approve. grin.

Ohm's law
Not just a good idea;
It's the LAW!

RE: Power Theft Prevention

I don't think installing copper bars is all that brave. Just need some gloves. Maybe different with voltages higher than in the US.
Residential meters are an all in one unit, so going around the meter is how most do diversion. Meters that require CT's is likely easer, but then again I believe there is a seal on the cabinet.
I also don't recommend it because opening a CT secondary makes bad things happen.

RE: Power Theft Prevention

Failing to take an interruption so as to avoid those dangers may serve to thin the gene pool of lower IQ thieves . . .


"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

RE: Power Theft Prevention

Are you also having a problem with copper theft? SA seems to have a really big problem there LINK.

RE: Power Theft Prevention

Another thought, on smart meters they record interruptions, and that maybe an indication of someone removing a meter.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close