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Old 08-03-2008, 08:31 PM   #1
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Can I shield or reduce the current being sensed by a Current Sensing Transducer?


Can I wrap a magnetic shield around the wire so it's in between the wire and sensor to ultimately reduce the tracked current? Will I need to do it for both wires in a 2 phase system to be effective?

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Old 08-03-2008, 08:42 PM   #2
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Can I shield or reduce the current being sensed by a Current Sensing Transducer?


I don't know how you would calibrate it.

Without seeing your setup, another way would be to solder a thinner wire in parallel with the one carrying the current and monitor this thinner wire.

So if the heavy wire measures 1 milliohm/ft and the paralleled wire is 10 milliohms/ft, it should carry approximately 1/10th the current, plus or minus a wide tolerance.
Errors will be introduced by the soldered splices and the change in conductor temp due to the current passing through it.
This setup you could calibrate.

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Old 08-03-2008, 09:08 PM   #3
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Can I shield or reduce the current being sensed by a Current Sensing Transducer?


Sorry, maybe I didn't make myself clear enough: The owners of our apartment building has recently (illegally) installed submetering for the electricity. I know a little about electrical systems, so I opened the circuit breaker box and saw two current sensing transducers (each placed around a thick wire) connected to a wireless data collecting device. My goal is to reduce the amount of current being tracked to effectively reduce my electrical bill.
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Old 08-03-2008, 10:48 PM   #4
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Can I shield or reduce the current being sensed by a Current Sensing Transducer?


Those current sensing transducers are actually current transformers. Commonly known as CT's.

Ct's always have a ratio of some sort. They come in all sizes from 30:5 up to 6000:5, maybe even bigger. Their purpose is to read huge current, then reduce it so it can be transmitted along small wires. Yours are likely 100:5 or 200:5.

Using the 200:5 as an example, if 200 amps were flowing in the big wire, 5 amps will be flowing in the small wire. At 100 amps, the output would be 2.5 amps. It's an exactly linear ratio.

Are you absolutely sure that these don't go to the power company meter? They're very common on larger services.

One thing to remember about CT's is never disconnect the small wires while there's current flowing in the big wires. To do so will cause the immediate destruction of the CT. Some of them will actually explode, the sides will bulge out on some, and some will just burn up inside. If you're not going to use them, short out the small wires.

They can be left in the circuit without any ill effects though. The power consumption of a CT is VERY small.

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Old 08-03-2008, 11:00 PM   #5
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Can I shield or reduce the current being sensed by a Current Sensing Transducer?


Micromind - They ARE connected to a meter reading company through a wireless connection. So I can't disconnect them entirely, because they would show a constant 0 reading and they would know something is up. I'm just trying to shield SOME of the current. Can I slip some sort of EMI shielding ring in between the big wire and the CT?
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Old 08-04-2008, 07:33 AM   #6
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Can I shield or reduce the current being sensed by a Current Sensing Transducer?


If you pass the wires of a big appliance back through the same loops then its consumption is counted backwards

You may pass some appliances hot wire back through the loop to exclude it from the calculation

You may pass the wire multiple times through the loop (all in backwards direction) to exclude the appliances consumption again and again . . .



Say your entire home uses 30 A and the lights use 2 A

Normally the meter will register 30 A

If you pass the wire back you will have home less lights = 30 - 2 = 28 A. This is like if the meter ignores the lights

If you pass the wire second time this will be 30 - 2 - 2 = 26 A and so on
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Old 08-04-2008, 08:36 AM   #7
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Can I shield or reduce the current being sensed by a Current Sensing Transducer?


Quote:
Originally Posted by copper00 View Post
The owners of our apartment building has recently (illegally) installed submetering for the electricity.
My goal is to reduce the amount of current being tracked to effectively reduce my electrical bill.
Just don't get into a situation where you could even be remotely accused of defrauding PoCo; then the fight is between you and PoCo and not between you and the apt. owners.
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Old 08-04-2008, 08:59 AM   #8
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Can I shield or reduce the current being sensed by a Current Sensing Transducer?


Quote:
Originally Posted by Yoyizit View Post
Just don't get into a situation where you could even be remotely accused of defrauding PoCo; then the fight is between you and PoCo and not between you and the apt. owners.
He is right
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Old 08-04-2008, 09:11 AM   #9
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Can I shield or reduce the current being sensed by a Current Sensing Transducer?


Quote:
Originally Posted by copper00 View Post
My goal is to reduce the amount of current being tracked to effectively reduce my electrical bill.
This would be theft. The penalties are very severe when you get caught. And power companies have seen it all when it comes to people trying to cheat them.
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Old 08-04-2008, 09:57 AM   #10
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Can I shield or reduce the current being sensed by a Current Sensing Transducer?


I appreciate everyone's concerns - But I consider the landlord's actions as THEFT. The electric was included in the rent for 25 years and all of a sudden they decide to charge us? They've also been raising the rents about 15% per year for the last 5 years. They're obviously profit hungry.

The metering gets collected by a little billing company, and the PoCo is not involved at all in terms of the info collected from each individual apartment. BTW - There are 250 apartments in the building.

So can I wrap a piece of Mu-Metal around the the main current wire to shield the CT readings somewhat? Will this work?

I'm not willing to do what Ash suggested, that's gonna get way too messy. Thanks Ash and all for taking the time in helping me.
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Old 08-04-2008, 11:55 AM   #11
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Can I shield or reduce the current being sensed by a Current Sensing Transducer?


Quote:
Originally Posted by copper00 View Post
I consider the landlord's actions as THEFT
I sympathize, but. . .

http://www.lectlaw.com/def/c202.htm

And, as previously mentioned by JRCLEN, "Theft of services is the legal term for a crime which is committed when a person obtains valuable services — as opposed to goods — by deception, force, threat or other unlawful means, i.e., without lawfully compensating the provider of said services."

Last edited by Yoyizit; 08-04-2008 at 12:13 PM.
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Old 08-04-2008, 01:33 PM   #12
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Can I shield or reduce the current being sensed by a Current Sensing Transducer?


You should know what is possible and make the right decision. I am happy you decided not to do this

Theft from thieves is still considered theft. It it was otherwise you might steal everything and blame its owners



What i suggest you to do is

A. save elecctricity in order to minimize your bills in perfectly legal way

B. find another way to escape from your home owners. Maybe turn your back on them and find a better home with better people
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Old 08-04-2008, 02:09 PM   #13
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Can I shield or reduce the current being sensed by a Current Sensing Transducer?


This thread should be closed. I can't believe the OP is even suggesting or asking about this on a public forum.
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Old 08-04-2008, 03:19 PM   #14
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Can I shield or reduce the current being sensed by a Current Sensing Transducer?


This is now closed, please refrain from asking question about how to perform theft of services on the web site.

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