Month: January 2017

Reducing Inventory with High Accuracy CTs

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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.









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Extended Range CTs VS High Accuracy CTs

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Extended range CT’s are all the rage with CT sales people now. But what exactly is and extended range current transformer? Don’t we already have high accuracy CT options out there? Is there a difference in extended range current tranformers and high accuracy current tranformers? 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?

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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.









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Socket Type Meters

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Socket type meters, also known as S base meters, are the most common electric meters out there today. What are the characteristics of a socket type meter? Where can they be used? What types of socket type meters are there?

What are the characteristics of a socket type meter?

Socket type meters are characterized most notably by the blades on the back of the meter. The meter baseplate holds all of the metering components. It has blades that come out of the the back of it. These blades plug into a meter socket. Hence the name socket type meter. What must be noted is the fact that the number of blades on the back of the meter varies based on the type of meter it is. This means that there are different meter sockets as well to accommodate the different types of meters.

Socket type meters are easy to install and remove. They just “plug in,” so to speak, just like plugging a cord into a receptacle. Because socket type meters can be plugged in, this means that they can make and break the load. Or, in easier terms, they can be used to turn the power on or off simply by pulling and reinstalling the meter.

Since socket type meters are so easy to install and remove they make it easy to perform maintenance. Many utilities have testing programs where all of the meters are changed-out on a cyclical basis to perform testing.




A socket type meter is usually denoted with an “S” after the form number. For example, a form 2s meter is a socket type meter because of the “S”.

Where can socket type meters be used?

They can be used in all sorts of situations. They can be used to meter residential, commercial and industrial customer. In fact, most homes, at least in the U.S. are utilizing socket type meters today. These types of meters are the go to meter. Socket type meters are also often used as sub meters. They are cheap and easy to install which is what makes them so popular.

What types of socket type meters are there?

The short answer is all of them. There are form 2s meters all the way to form 9s meters with every thing in between. This allows the socket type meter to be used to meter every type of service out there. These meters are also often times fitted with demand registers to allow them to meter demand. And with the electronic registers, these meters are now more capable than ever.









All about A Base Meters

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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.