Hot Sockets in Meter Bases









Hot sockets are one of the things hot socketthat you will encounter if you spend anytime working in self-contained meter bases or changing meters. Here I want to discuss a few things that cause hot sockets, what kind of damage a hot socket can cause and what to look for when changing meters to spot a hot socket.

What causes Hot Sockets?

The biggest cause of hot sockets seems to be in my experience, loose connections. Loose connections can be at a couple of different places in the meter base. One of the places is where the wire attaches to the lugs. This is a notorious spot that heats up over time when it is not tightened properly. What happens is over time little micro arcs occur between the loose wire and the lug causing it to overheat. This, in turn, causes the socket terminal where the meter plugs in to overheat and voila, you have your first cause of a hot socket.

Another cause is the terminal or socket itself. In most meter bases these are spring loaded jaws that apply force to the terminals on the back of the meter. When the meter is pulled and set these jaws open and close back. Sometimes plastic boots are installed on the terminals of the meter in order to turn off a customer for non-payment or for any other reason. The more a meter is pulled in and out of these jaws the looser they become. When they get slack then tiny micro arcs happen which causes the terminal to overheat and we have another cause of a hot socket.

Yet another cause is the hot and the cold along with fluctuations in the load. As the metal in the terminals heats up and cools down due to the weather and load changes it expands and contracts. This over time can cause the jaws to loosen up and overheat.

A hot socket can also be caused where the terminal is put together or attaches to the bus bar in the meter base. Sometimes it is a screw or bolt and other times it is springloaded jaws that connect to bus bar. Either way, any slackness and you will eventually end up with a hot socket.

What kind of damage can a Hot Socket cause?

A hot socket is a very dangerous occurence. The worst thing it could cause is a house fire. You can see in the picures below that a hot socket in a meter base can lead to melted wire. It can also lead to overheated terminals on the meter itself. This causes irreversible damage to the meter to the point that the meter has to be replaced.

hot socket

Especially with the newer solid state meters there seems to be a lower tolerance for overheating of the terminals in a meter base. It is also not uncommon for customers who have hot sockets to experience flickering and dimming lights.

What to look for when changing meters?

When changing meters it is imperative that before pulling out any meter a quick visual inspection is done. This includes looking at the front of the meter and visually inspecting the wiring and terminals before pulling the meter out. It is very important not to take this step for granted. When terminals get so hot that they fail they can actually weld the terminals to the socket. This along with melted blocks in the meter base can cause a serious safety issue when pulling the meter.









So, look at the back of the meter the best you can before pulling it out. Once the meter is out you need to visually inspect the meter and the meter base before installing a new one. Some of the signs of an overheated terminal on a meter are discoloration and melting of the base plate. Likewise, some of the signs of a hot socket are discoloration and melted blocks and wire.

If you find this situation do not put a meter back in. The blocks, and possibly the wire and meter will all need to be replaced. Depending on you jurisdiction, this may be up to the utility or the homeowner to repair.

Conclusion

Hot sockets are something that every utility deals with. Be sure to be on the lookout for the causes and effects of hot sockets to keep those meters turning. As always, like us on Facebook and invite your friends!







Edison and the Electric Chair: A Story of Light and Death A Review








Recently I read Edison and the Electric Chair: A Story of Light and Death. I wanted to give a quick review of the book in case anyone was thinking about reading it.

Review

When I picked this book to read I thought that it would be more about the electric chair. Not that I am totally interested in the electric chair or the death penalty or anything. Also, I did not know that Thomas Edison had anything to do with the electric chair.

It turns out though that this book does not focus a ton on the electric chair. It does do a decent job offering a bit of biographical information on Thomas Edison. I feel like the book focused more on the battle between alternating current and direct current.

Obviously Thomas Edison was a proponent of his own direct current system over the alternating current of George Westinghouse. So, the book focused more on the war between George Westinghouse and Thomas Edison than it did on the electric chair. Which, in my opinion was not a bad thing.

The book talks about the discovery of the light bulb and how it changed the world. It also talks about how different electric companies started.

How does it relate to Metering?

There are actually a couple of mentions of meters in this book. One is from one of the metering pioneers Elihu Thompson.

What about Thomas Edison and the Electric Chair?

There is a good discussion of the electric chair and how it was chosen to become the new humane way of enforcing the death penalty. Several examples of different methods are described and there are pictures included as well. I am not going to spoil the book but it also talks much about Thomas Edison’s role.

Would I Recommend Edison and the Electric Chair: A Story of Light and Death?

The answer is yes. Overall I thought that it was a good book and I would recommend it. I was able to learn something and anytime you can learn something it is usually a good thing. If you are interested in checking this book out follow the link for Edison and the Electric Chair: A Story of Light and Death.









What is the difference between voltage and current?








Voltage and current are two different measures that are found in electricity. They are both present in every electrical circuit from the flashlight all the way to refrigerators. But, the question is what is the difference? To illustrate the difference between voltage and current we will look at the age old comparison of electricity to water.

Current Flow

Current is a bit easier to illustrate. We can compare it to water in a garden hose. Imagine you have a simple water wheel. To make this water wheel turn you need to pour water over it. Let’s say we have two different sized water hoses. One is 3/4″ and the other is 1″. Now, let’s pour the water over the water wheel with the smaller hose and see what happens. The water wheel turns. Now, the larger hose. What happens? The water wheel turns faster.

This is a result of more water flowing in the larger water hose. More water = faster water wheel. Pretty simple. We need to make sure that when we think of current in the same way as water in a hose that we always think of the hose as full all the time. That way when you turn the hose on you instantly have water flow.

In the early days of electricity it was a commonly held belief that electricity was a fluid. This fluid was made up of tiny particles that would flow into different materials.

Voltage, the Driving Force

Again we are going to compare voltage to the water system. First remember that voltage is the driving or electromotive force that is a part of electrical circuits. How does this translate to water? Think of the voltage as the pressure in a water system.








With the two hoses from the example above how can we make the smaller hose move the water wheel faster? With more pressure of course. So, with more pressure the smaller hose can make the water wheel turn faster. How does this relate to voltage?

Example

Look at the distribution lines above your head next time you are out and about. The wires on these lines carry thousands of volts. However, they are not very big. Remember Ohm’s Law? Let’s say you have a 2,500 watt motor. This is a multi-voltage motor. Meaning that you can wire it a couple of different ways depending on the voltage available. You need to run new wires to this motor, but what size do you need? That depends on the voltage.

Wait, I know what you are saying. Wire is sized by the number of amps. You are correct. However, depending on the voltage we may be able to run a smaller wire therefore possibly saving money. If the voltage in this case is 120 then the amperage will be 2,500/120 = 20.8 amps requiring a 10 gauge wire. If the voltage is 240 then the amperage will be 2,500/240 = 10.4 amps requiring a smaller 12 gauge wire.

Conclusion

Voltage and current are two different quantities that go hand in hand. Voltage is the driving force while current is the flow of electrons in the circuit.









What is Electric Current and how it relates to Metering








What is electric current? A good question indeed. What is the unit of measure for electric current? How can we measure electric current? And finally how does it relate to metering? These are the questions that will be tackled in this post. So, let’s get started with the first one.

What is electric current?

Electric current is the flow of electrons in a circuit. It is also what is used to power our stuff. Remember that in a circuit we have both voltage and current available. But, without the current flow our electrical stuff does not move. So, now that you know that electric current is the flow of electrons in a circuit what is the unit of measure used?

What is the unit of measure?

Current is measured using what are known as amperes, or amps for short. This is typically notated as an “A” in formulas but can also be notated as an “I”. This “I” stands for intensity of current. As with any unit of measure amps can be smaller or larger. So, it is not uncommon to see milliamps or kiloamps. Milliamps is typically notated as mA and kiloamps as kA. So, now that you know the unit of measure, how do you measure amps?

How do you measure Amps?

Amps, or electric current, are measured using what is known as an ammeter. An ammeter can come in a couple of different varieties. There is the common clamp on ammeter. The clamp on ammeter comes with a spring loaded jaw that enables you to open the jaw and place it around the conductors. This places the ammeter in parallel with the circuit. Clamp on ammeters can be found in digital and analog variants.

Another type of ammeter is placed in series with the circuit. These are typically found on multimeters. Also, when an ammeter is placed in series in the circuit it typically is not able to measure a very substantial load. Make sure you read the specs on your meter before you place it in series in any circuit.







How does electric current relate to Metering?

Ah yes, finally, the meat of the article. Electric current is very important to metering. This is because we are essentially measuring the changes in current flow. Remember that using Ohm’s law and the power formula that Watts = Volts x Amps. This means that the amount of watts used are in direct proportion to the amount of current that is being used. As the amps go up, so does the watts. As the amps go down so do the watts.

We as meter techs should know how amps relates to watts and how to convert amps to watts. We should also know how to go the other way and convert watts to amps. This will help us in troubleshooting with customers. Let’s have an example.

A customer is complaining of a high bill. You go to the meter and notice it is spinning pretty fast. So, you take the cover off the meter base and check the amperage. Let’s say that it is 30 amps. How do you convert this 30 amps to watts? Using Ohm’s law we plug in the numbers. Assume this is a 240v service. W = 240 volts x 30 amps = 7,200 watts. Let’s convert that to kilowatts and divide 7,200 by 1,000. We get 7.2 kw. This means that whatever the customer has on is pulling 7.2 kw and if left on for one hour it will use 7.2 kwh. A load like this could mean that an appliance like the air conditioning is not functioning properly and is running all day.

Conclusion

Electric current is one of the most important units we have in metering. It is measured by using ammeters and its unit of measurement is the amp. Using Ohm’s law we can convert amps to watts and back again.








What is Voltage and how it relates to Metering








What is voltage? This is certainly an important term to know in the electrical field. You hear it all the time. What is the voltage on the machine? Or, can you check the voltage on that circuit? We hear it, we say it but, what is voltage and how does it relate to metering?

What is voltage?

The most commonly used voltage definition states that voltage is the difference in potential between two points in a circuit. What a definition of voltage right? Another way that voltage is defined is by talking about water. Some find it easier to understand the voltage definition when we talk in terms of water pipes. Voltage is the driving force in an electrical circuit. We can think of it as the pressure in the circuit. So, what is voltage? It is the driving force in an electrical circuit.

How is voltage measured?

Voltage is measured using a voltmeter. With a voltmeter we can choose two different points in the circuit to measure the difference in potential across those two points. The unit of measure for voltage is known as the volt. The volt is named after Alessandro Volta who created the first battery known as a voltaic pile.

How does voltage relate to metering?

Ah yes, the big question is, how do we use voltage in metering? Well, we have to remember that meters measure kilowatts. So, what does that have to do with voltage? To find the kilowatts, we first need to find the watts. To calculate watts we need to know the current and the, you guessed it, voltage. Using Ohm’s Law we know that power is equal to voltage times current or stated mathematically, P = I x E. There are several ways you can remember this formula. One is by remembering the word PIE. Another is to change the letters to W = V x A.








In the first example, P = power measured in watts, I = current measured in amps, and E = voltage measured in volts. Just a quick fact here, E is the letter used because it stands for electromotive force which is a fancy way to say voltage.

In the second example, W = watts, V = voltage, A = amps. So, the two equations are equal they are just using different terms. The easy way to remember W = V x A is to think of West Virginia or W VA. Pretty simple right.

So, now that we know the terms we need to know how they relate to metering. Well, the nominal voltage in a typical metering circuit remains pretty much constant. A common household voltage is 120/240. So, the meter measures this voltage and then multiplies the voltage times the current in the circuit to get watts. And then as if by magic the readout is in kilowatts.

What?

Look at the equations again and go back to algebra I. If the voltage stays constant and the amperage goes up that means that the wattage will go up. If the amperage goes down, the wattage goes down. To get kilowatts from watts, divide the watts by 1000. In the older electromechanical meters the voltage coil, also known as potential coil, produced a magnetic field in the meter. When current flows through the meter it produces a magnetic field as well. The interaction between these two fields are what causes the disc to turn. So this is why it is important to make sure that the meter chosen for each installation is crucial.

Conclusion

Voltage is the driving force behind each and every electrical circuit. We can use Ohm’s law to calculate watts using the power formula. It is the interaction of voltage and current in a circuit that causes the meter disc to spin. To check the voltage in a circuit we use what is called a voltmeter.









Truper Automatic Wire Stripper Review








An automatic wire stripper can really add to your arsenal of electric tools. The ability to quickly, easily and cleanly strip wire can increase your productivity and reduce waste. Until the automatic wire stripper came about, you really had two options. You could use your knife to strip wire, or you could use a regular wire stripper like the Klein Tools 11047 Wire Stripper/Cutter. What I want to do is give my review of the Truper Automatic Wire Stripper.

Using a knife to strip wire works but there is always the risk of cutting yourself in the process. There is also the risk that you may nick the wire and degrade its capacity. You can also use the standard wire strippers. They work well but there is some skill involved with those as well. You need to know your strippers to know which slots correlate to which size wire. There is also a risk of cutting into the wire as well.

Truper Automatic Wire Stripper

truper automatic wire stripperThese wire strippers can be used to skin wire from 22 AWG – 10 AWG. This gives you a very wide range of wire sizes to choose from. And the best thing about them is that they are automatic. This means that you will not need to squint really hard to see which hold in your regular wire strippers you need to use. You just lay the wire in there and squeeze. That’s it!

I have used normal wire strippers for most of my career. I have also used a knife to skin wire for most of my career as well. So, when I bought these automatic wire strippers I was a bit skeptical. But, they really do a great job of stripping the wire.

Details

truper automatic wire stripper jawsThe Truper automatic wire stripper features a guide that can be set up so all of your strips are the same length. This can be very useful for really anything you are doing. If you are making up a panel and you want all of your strips to be the same length so that just the right amount of bare wire is under the connector, you can do that. All you have to do is move it until you get the right length. Then set it and forget it. It really is that easy.

These automatic strippers also feature a wire cutter. However, it is not the best. It is located between the handles so you do not get a ton of leverage. When I was using them there were a few times where it did not cut all the strands of the stranded wire I was working with. But, these are not really made for cutting wire, they are made for stripping wire. If you are looking to cut wire then check out my review of the Truper Lineman’s Pliers.








Another feature of the this automatic wire stripper is the ability to crimp wire. It offers three different positions for crimping. Again, these are in the middle of the handles. I have never had good luck with any strippers or wire crimpers where the stripping, cutting or crimping is in between the handles.

The grips on these automatic wire strippers are comfortable. They offer plenty of leverage to carry out fast and precise wire strips.

Conclusion

The Truper Automatic Wire Stripper is a tool I wish that I would have had many years ago when I started in the meter field. I think about all of those meter bases I have wired up through the years where I used my knife or regular wire strippers to skin the wire. All of those CT’s and PT’s that I have wired up through the years could have been done much faster.

I highly recommend this tool. After using this tool on the first job you will not regret buying it. It makes stripping wire practically effortless.









Truper Heavy Duty Lineman’s Pliers Review








Lineman’s pliers are one of the most important hand tools in a meter tech’s arsenal of tools. A good set of lineman’s pliers allows you to cut and bend wire with ease. They also need to be durable enough to be used at times as a hammer. Now, trust me I know that they are not a hammer but can you honestly tell me that you have never used your pliers to beat on something? One of the things that meter techs use lineman’s pliers for is cutting meter seals. Most of these types of meter seals have a steel wire which is harder than copper. This means that the pliers must be up to the task of cutting the steel day in and day out.

Now, I know that the Klein Tools 9-Inch High Leverage Side Cutting Pliers are pretty much the standard in the electrical field. But what if you need a set of pliers that work just as well but are different than everyone else? Are there any options out there?

Truper Heavy Duty Lineman’s Pliers

Truper Heavy Duty Lineman's Pliers

Truper is not a new company but it is not as well known in the electrical field as names like Klein, Greenlee and Ideal. But, they do make a good set of lineman’s pliers. Their 9″ heavy duty pliers are made of forged chrome vanadium steel which is supposed to be two times stronger than carbon steel. They also feature a good comfortable grips. The finish on the pliers is a satin finish which helps with rust resistance.







My Review

Truper Heavy Duy Pliers LengthSo, what do I think about the Truper Heavy Duty Lineman’s Pliers? All in all I think that they are a good tool for any toolbox out there. I do not think that you would be disappointed if you made the purchase. Now, there are a couple of things that I would like to mention about these pliers. The overall length is about 9.5″. The distance from the pivot point to the end of the handle is about 7.5″. This means that you get good leverage when using these pliers.

The grips are comfortable and they offer a raised portion to help aid in holding on to the pliers. I also feel like this helps keep your hands from slipping if you need to use the pliers to push something as well. I also want to note that the grips are not for use on live circuits. So, keep that in mind when using these pliers. I have used Klein Pliers most of my career and one difference that I notice between these and the Klein are that the head of Truper pliers seems to be larger. That could be a good thing if you are using the pliers to bang on things because of the added mass. It could also be bad if you need to get into tight spaces.

My biggest complaint with the pliers is the jaw design. You can see in the picture below what I am talking about. Just below the cutters there is a gap when the jaw open. More than once while using these pliers to cut wire the wire has fallen into that gap. This prevents you from cutting the wire because the gap portion clamps down on wire. Once you get used to it, there is no problem. Just something I though I would point out.Truper heavy duty lineman's pliers jaw

Conclusion

Would I buy the Truper Heavy Duty Lineman’s Pliers? The answer is yes. Although they are not perfect they are perfectly capable of handling any task with ease. Whether it be cutting, bending, pulling wire or wiring up CT’s these pliers get the job done.









Increasing Revenue with High Accuracy CT’s








Increasing revenue is something that we all want to do. High accuracy CT’s can help us achieve that goal. When it comes to instrument rated metering installations we have to remember that our meter is only as accurate as our CT’s. So, the first step in making sure we are accurately measuring our metering installations is making sure we have the most accurate CT’s installed.

Standard Vs. High Accuracy

This is where high accuracy CT’s come into play. Remember that standard current transformers are only guaranteed accurate to within 0.3% from the nameplate value to the rating factor. Also, standard CT’s are 0.6% accurate from 10% of the nameplate value up to the nameplate value. This means that for a common 600:5 CT that anything below 60 amps is not guaranteed to be measured accurately. So, what do you do?

You install a high accuracy CT that is 0.15% accurate from 5% of its nameplate rating through the rating factor. Now, using the same 600:5 ratio as an example, we are now able to measure down to 30 amps with 0.15% accuracy. This is high accuracy CT’s are used to help with increasing revenue.

Where can high accuracy CT’s help with increasing revenue?

One of the places where high accuracy CT’s can help with increasing revenues are department stores or industrial factories that have been converted to warehouse space. These types of customer changes can cause revenue losses because the infrastructure that was put in for these larger customers who have now left or have converted their spaces is no longer being utilized.








Let’s say that the customer was doing some small scale manufacturing and decided that the space was no longer big enough for its manufacturing needs. So, they decide to move into a larger space and convert this previous space into warehousing. Let’s keep with the standard 600:5 for this example. For this example let’s also assume that the rating factor of this standard CT was three. We are also going to assume that we were using this rating factor. Meaning that this was a 1200 amp service and we installed 600:5 CT’s with a rating factor of 3, to make sure that the CT’s were as saturated as possible.

The customer in this example typically pulls around 750-800 amps. This is well within the range of our standard accuracy 600:5 CT’s. Now when they leave, they take all of the manufacturing equipment with them and only leave a few lights. There new load is now only around 40 amps. They do not need to heat or cool the space because what they are storing does not require it. So now, the standard 600:5 CT is not guaranteed to measure the 40 amps accurately.

What if we had installed a high accuracy CT?

If we had installed a high accuracy CT to begin with then we would not be worried. The high accuracy 600:5 CT is able to measure down to 30 amps with 0.15% accuracy. This means we capture those 40 amps and we do so accurately. This is how high accuracy CT’s play a vital role in increasing revenue.

Conclusion

In conclusion, if you are concerned with increasing revenue make sure that you are giving a look to high accuracy CT’s. They can be placed anywhere your standard accuracy CT’s are and can instantly start increasing revenue. High accuracy CT’s help mitigate low current situations such as when large customers move out or convert. If you are in the market for high accuracy CT’s check out Peak Demand.









Reducing Inventory with High Accuracy CTs








Reducing inventory is a big concern with utilities these days. This is primarily driven by the fact that reducing inventory means reduced costs. Reducing costs means that the profit margin can be higher. So, what does that have to do with high accuracy CT’s? How can high accuracy CT’s reduce inventory?

Use the Extended Range of High Accuracy CT’s

When placing new CT’s in service we traditionally had a variety of different CT ratios to choose from. Among the most popular are 200:5, 400:5 and 600:5 variants. This means that when a new service is built the meter tech or engineer will look at the service and size the CT’s according to the projected load. This is done because we want the amps on the service as close to the nameplate rating as possible. We do this because standard CT’s are most accurate at their nameplate rating up to their rating factor.

So, if we have a 400 amp service that is projected to normally run around half of that or less we may use 200:5 CT’s with a rating factor of at least two. This ensures that when the amperage is low we can measure it as accurately as possible.

Enter the new kid on the block. The high accuracy CT. With the high accuracy CT, with its extended range features we can now use one size CT for most of our installations. For instance a 600:5 high accuracy CT will allow us to measure down to 30 amps. But there is more. Many manufacturers are offering these high accuracy CT’s with extended ranges that can measure down even further.



How can High Accuracy CT’s be useful in Reducing Inventory?

High accuracy CT’s can reduce inventory by reducing the number of different ratios that you need. You can now purchase a 600:5 CT with a rating factor of 2 or more that can cover all your needs. This means that you no longer need to use 200:5 or 400:5 CT’s. You can stock one size. This allows you to purchase less. Even if you do not have a new job coming up, in the past you would have needed to keep a certain number of 200:5 and 400:5 CT’s on the shelf for emergencies.

So, instead of having a couple of sets of each size, you can have just a couple of sets of 600:5 CT’s that can be used for each service type. Instead of having purchased four sets of CT’s now you have only purchased two. This is beneficial to reducing inventory and cutting costs. Also, it leads to a reduction in storage space as well.

Conclusion

High accuracy CT’s can be a great way of reducing inventory in your meter shop or warehouse. Look at what you have stored in your warehouse and see if you could benefit from reducing the number of CT’s that are just sitting on the shelf as spares. If you are interested in high accuracy CT’s check out the offerings from Peak Demand.









Extended Range CTs VS High Accuracy CTs








Extended range CT’s are all the rage with CT sales people now. But what exactly are they? Don’t we already have high accuracy CT options out there? Is there a difference in extended range CTs and high accuracy CTs? I will try and break these terms down and explain what the difference is between extended range CTs and high accuracy CTs.

What are Extended Range CTs?

To understand what extended range CTs are we need to understand what standard range CTs are. Standard range CTs have a measurement range from 0 amps through their rating factor. However, notice that I said measurement and not accuracy. That is because if we remember correctly that standard CTs are only certified as being accurate to 0.6% from 10% of their nameplate rating through the nameplate rating. Furthermore, at the nameplate rating up through the rating factor they are accurate to within 0.3%.

So, obviously an extended range CT would be better than that right? Well, yes. However, there is a caveat. That being that there is no standard when it comes to the term “extended range CT.” These extended ranges are noted in the literature that comes from the manufacturer of the CT. This means that the CT could be accurate down to 3% of the nameplate value or even down to 1%. This however all depends on the manufacturer. Which leads us to our next point.

Don’t we Already Have High Accuracy CTs?

The answer to that question is yes. But let’s remember that to be classified as a high accuracy CT that there are certain guidelines that must be adhered to. The IEEE is the body that defines that standard. If you want to learn more about high accuracy CTs follow the link. So the next question then is why do we have extended range CTs if high accuracy CTs already exist and is there a difference?



What is the difference between extended range CTs and high accuracy CTs?

The first difference is that high accuracy CTs actually have a standard that must be met to be called high accuracy. Extended range CTs however do not have this standard. However, most extended range CTs are high accuracy CTs. The reason for this is because manufacturers need a way to separate themselves from the competition. It is not good enough for them to just meet the standard. They need to go above and beyond the standard to attract more customers.

This is good for utilities because it means that in the end they have access to more choices and better products. Utilities who want high accuracy CTs will find that not only are they available but they are available with more extended ranges than the standard requires. Just remember also that an extended range CT is not always high accuracy. Check and make sure that the CT has a rating for high accuracy before believing the salesman. Extended range is something that the manufacturer decides.

Conclusion

Extended range CTs can be used anywhere standard CTs are used. They allow you the ability to meter lower levels of current than you would have before now. This also permits greater revenue over the life of the CT. However, make sure that the CT is high accuracy before you jump on the extended range bandwagon.









What are High Accuracy CT’s?








High accuracy CT’s are becoming more and more popular with utilities these days. Because of new manufacturing processes and materials, manufacturers such as Peak Demand are now able to make their CT’s more accurate. But, more accurate than what? Just saying that a CT is high accuracy still does not tell us what it is. So, what is a high accuracy CT?

What is a Standard Accuracy CT?

To understand what makes a CT “high accuracy,” we first need to know what the standard accuracy of a revenue grade CT is. To be classified as a revenue grade CT the IEEE states that it must be a Class 0.3. Well, that really does not tell us much. Class 0.3 means that the CT must be accurate to within 0.3% of the nameplate rating up to the rating factor.

We can use a common Class 0.3,  600:5 CT with a rating factor of 2 to create an example. From the nameplate value of 600 amps all the way up to 1200 amps when using the rating factor, the CT has to be accurate to within 0.3%. However, below 600 amps, more specifically from 10% of 600, which is 60 amps, all the way to 600 amps the CT only has to be 0.6% accurate. Below 60 amps the accuracy is not guaranteed. Thus the need for a higher accuracy solution.

What is a High Accuracy CT?

A high accuracy CT is a Class 0.15S. This means that the CT must be accurate to within 0.15%, but there is more. Not only does the Class 0.15S have a closer accuracy tolerance range, the ampere range is greater as well. Now, instead of only being accurate from the nameplate rating up to the rating factor, the CT must be accurate all the way down to 5% of the nameplate value.




We can use a Class 0.15S, 600:5 CT with rating factor of 4 to create another example. In the previous example the CT was accurate to within 0.3% from 600 amps all the way to 1200 amps. From 60 amps to 600 amps the CT was accurate to 0.6%. And below 60 amps there was no guaranteed accuracy. Now with the Class 0.15S 600:5 CT the accuracy is guaranteed from 5% of the nameplate value all the way to the rating factor. So, from 30 amps all the way to 1200 amps the CT is 0.15% accurate. What a difference. This offers a very big advantage to utilities.

Conclusion

A high accuracy CT can be a great solution for any utility that is looking to increase their revenue. Manufacturers like Peak Demand have high accuracy solutions available such as their Alta Series™ of High Accuracy 600V Metering Current Transformers line. The next time you are in the market for CT’s think about using high accuracy CT’s instead of the standard Class 0.3 CT’s you have been using all these years.









All about A Base Meters








A base meter

A base meters are one type of meter that has been used for many years. What are the typical characteristics of an A base meter? What are A base meters used for? How many different types of A base meters are there?

 

What are the typical characteristics of an A base meter?

Older A base meters typically had a baseplate that was flat on the back. This held all of the components of the meter and gave them a base to mount to. The base was flat because the meter was mounted to the wall inside a meter base enclosure. The older A base meters were characterized by a rectangular bottom where the terminals were and a rounded top. This is also where the globe and disc assembly were mounted.

The connections to an A base meter are on the bottom. This is also where the power is brought in. It is also where the power is sent to the customer in the case of a self-contained meter. These meters can be used, depending on the type of meter it is, with single phase or three phase power. A base meters are also used in transformer rated installations as well. In this case they are used with CTs and PTs.

What are A base meters used for?

A base meters are used for metering residential, commercial and industrial customers. Although they are not as widely used as they once were, A base meters are still in use today. There are also even models that are available with AMR and AMI modules installed. This allows easier reading and communications than were once possible. When used with most residential customers an A base meter will normally have four terminals. Two of the terminals are line in terminals and the other two are line out terminals.








So, to figure out which are which you can do a simple test with a voltmeter. Note that this only works if the meter is energized and the power is on to the service. To figure out which terminals are which check the voltage between each terminal. So, start with the far left terminal and check it against the one beside it. If you get a voltage then those two are different phases. If you get zero then those two are the same phase.

A base meters are also used for commercial and industrial customers. However, in this capacity they are normally used as transformer rated meters. If this is the case they will normally be enclosed in a large meter base with a glass window on them so the meter can be read without opening the meter base.

How many different types of A base meters are there?

Well, this can be sort of a loaded question. The way that I look at this question is how many different service types can be measured by an A base meter. And the answer to that is, all of them. There are A base meters that can meter the entire scale of service types. Whether it be 120/240v, 240v delta, 120/208v etc. So, there are just as many meter types in the A base world as there are in the S base world. This means that for whatever need you may have an A base will cover you.

Conclusion

A base meters were once a mainstay in the electric meterman’s arsenal.

They are not used nearly as widely as they once were but they can still be a viable option for those older installations where an upgrade may be difficult or too expensive. Furthermore, A base meters are characterized by flat baseplates and terminals on the bottom. They are also used in many different types of installations. This also means that there are many different types of A base meters still out there in use today.







What are test switches for?









Every now and then in the electric metering field you will run across a transformer rated metering installation that does not have a test switch. Is this a good thing or a bad thing? Most CT rated installations require that test switches be installed. These switches can be used for a few different things. To test the meter, to shunt the CT’s, to safely remove the CT rated meter from service and they can also be used to check the voltage and the amperage on the service without actually having to open an enclosure or go into a fence.

Why do certain installations not utilize test switches? The answer here would most likely be cost. The meter bases or CT rated installations that you will typically find without test switches are form 3s and form 4s meter bases. Form 3s and form 4s meters are many times found on large residences and sometimes large temporary services such as construction services or school trailers that are not thought to be in service very long. The cost of installing the test switch along with the cost of the larger meter base to hold the test switch is often times a deterrent. Also, in the case of residences one could argue that they just do not use enough power to justify putting a large meter base and test switch on the wall because the meter will be changed out when all of the form 2s meters are changed on their neighbors homes.

Installing a transformer rated service without a test switch can be a bad thing. One thing that you have to remember is that when you pull the meter in a CT rated service and you do not use a test switch is that you are opening the circuit of the secondary side of the CT. This leads to a build up of voltage on this circuit which is dangerous to metering personnel. The proper procedure without a test switch would then be to shunt the secondary side of the CT before pulling the meter.

Test switches can be used to test the meter. With different types of test equipment they can be used to test the meter in service using the load that is available at the customer’s site. This can be a good test to show exactly how the meter is metering the service under the load that is currently on the service. You can also test the meter using a phantom load while it is still in the meter base using the test switches.








Test switches are also used to test the CT’s in the service. You can use various different types of test equipment to test the CT’s. You can test the burden on the CT circuit as well as determine how many amps are on the CT circuit as well.

To remove the meter from service you need to shunt the CT. There is a switch that does this for you. Shunt the CT out and you can safely remove the meter from service. You can also use the test switches to remove all voltage from the meter as well before removing the meter from service and before installing the meter in service.

With the new regulations regarding arc-flash hazards and safety, many utilities have adopted safety policies that no longer allow their personnel to work inside energized cabinets, pad mount transformers or other enclosures if the service is too large or if the voltage is too high. This is yet another thing that the test switch can be used for. It can be used to check and make sure that the customer is getting the proper voltage. You can also check the rotation in the meter base at the test switch as well.

All in all, it is a good practice to install test switches in all of your CT rated metering installations. They will allow you to test the meter in service, test the CT’s in service as well as allow you to check voltage and rotation. Test switches also allow you to safely install and remove meters from service by isolating the blocks of the meter base from current and voltage.








The Meter Technician Profession

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So you are thinking about getting into a career in the electric utility industry and you are not really sure what you want to do. There are several career paths that you could choose. A few are power lineman, or engineer, or even maintenance mechanic. What I want to persuade you to do is to think about becoming an electric meter technician.

The electric meter technician is possibly a job that you have never even heard of. In addition, you may have never given any thought to becoming one. So what does and electric meter technician do?

Well, contrary to popular belief, we do more than just read watthour meters. We are not just “meter maids” as some lineman would have you think. Electric meter technicians do read electric watthour meters. But we meter techs also do much more than that.

To be an electric meter technician one should have, or be able to develop, a strong electrical background. Furthermore, you will want to have graduated high school. In addition, if possible, have taken some college courses in electrical theory. It would be even better if you could get an associate’s degree in electrical technology. This education will be helpful in understanding how watthour meters work. It will also help in understanding how the entire electric utility works as a whole.

Electric meter technicians test watthour electric meters either in the shop with test equipment or in the field with watthour meter test equipment. They also check residential, commercial and industrial metering installations for proper wiring and metering accuracy. There are meter techs who specialize in some of these areas. Some meter technicians only deal with residential metering installations and customers. Others deal only with commercial and industrial customers. While others may only stay in the shop and test watthour meters.

The ideal electric meter technician will be able to work outside all day. Outside the meter tech will do things such as change out electric meters, check on high bill complaints, low consumption or stopped meter orders. Meter techs will also work outside installing new metering equipment on instrument rated metering applications.

The electric meter technician will also be called upon to explain billing to customers.







Many times customers do not understand their bill and the meter technician is usually the last person the customer will talk to. The customer has normally already called in and talked to someone on the phone. They were not satisfied over the phone and now want to talk with someone in person. The meter technician is that someone. Because of this the meter tech will need to have strong interpersonal skills to be able to answer the customer’s questions. In addition they will also need to be as professional as possible. You do not want to go out a customer’s residence or business dressed like a slob. That ruins your credibility right away.

Electric meter technicians will also need to be able to perform above basic tasks on the computer. Part of the job requires the meter tech to be able to program watthour meters, download information from the meters, create new programs for the meters as well as run reports out of the billing system to find out if there are any errors. You will need to have an eye for detail. Many times you will be looking for something that stands out as unusual. Being able to determine from that information if there is a problem that needs to be checked and repaired is crucial.

An ability to do algebra also comes in handy as well. Electric meter technicians also use many formulas to complete their work. If current transformers and potential transformers need to be installed you will need to know how to calculate the multiplier. Also, you will need to know how to size the current transformers to the service to be metered. Another thing that you will need to be able to do is calculate and electric bill with demand. Many times customers will not understand demand. So it will be up to you to explain it to them in a way they can understand. There will be times that you will need to explain the math to the customer so that they understand what is going on.

Being a meter technician is a highly rewarding career. Notice that I said career and not job. The electric meter technician is a specialized field and most who are in the field work until retirement. Which also means that there are not a ton of jobs available. So when you get one, keep it! Also worth noting is that it will typically take between 5-7 years to become fully proficient as a meter tech. But even then you will constantly be learning new technology.

So, with that I hope that you give the electric meter technician career a chance.