Month: December 2016

Primary Metering vs Secondary Metering

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Primary metering and secondary metering are two different ways of metering the usage of different customers. Though the way they are installed differs, there are some similarities as well. There are also reasons why you choose primary metering over secondary metering and vice versa.

What is the Difference Between Primary Metering and Secondary Metering?

The biggest difference between primary metering and secondary metering are the voltages. In primary metering, the metering is installed on the high voltage lines. Many times when referring to primary metering we are talking about distribution lines. Some common voltages for distribution lines are 12,470v and 24 kv.

Since primary metering installs its equipment on the primary, the metering equipment is rated for this higher voltage. This means that the instrument transformers, CTs and PTs, are bigger than what you would find in a secondary metering installation. Primary metering installations are typically found in three places. They are found overhead on a pole, underground in an enclosure, and they are found in substations.

Whether on a pole, in an enclosure or in a substation, a primary metering installation uses basically the same things. Depending on the type of service, from one to three CT’s and PTs are used.

In secondary metering installations the voltage is lower than in primary installations. Secondary metering is installed on the secondary outputs of both overhead and underground transformers. It can also be installed in CT cabinets or at the riser of an overhead installation.

Depending on the utility PTs may be optional on voltages over 120v. Other utilities require PTs on anything over 240v. This is my recommendation.








What are the Similarities Between Primary Metering and Secondary Metering?

Actually, they are quite similar. The secondary sides of the CTs and PTs wire the same. They are both marked with H1 H2 and X1 X2. This lets you know where to put your wires. Believe it or not, you actually use the same meter form numbers for both. Obviously this depends on the service being metered of course. If you have a single phase tap line that you want to meter with primary metering you have one CT and one PT. You can meter this with a form 3s meter. Just like if you were to have a two wire secondary service. You can use a form 3s meter.

The meter multipliers are calculated the same way. Use the CT ratio times the PT ratio and you have your multiplier.

Why Choose Primary Metering Over Secondary Metering?

This is best described with an example. Lets say that you own an apartment complex and the utilities are included with the rent. The tenants do not pay electric bills to the power company. Instead of having an hundred power bills in the mail every month you have one bill with the total usage.

The same works if you are large factory with several buildings all feeding off of the same primary. You can get one bill from just one meter. This may actually save you money as well in demand charges as well as facilities fees. Check with your utility on this though.

Another scenario may include metering a cryptocurrency operation.

Why Choose Secondary Metering Over Primary Metering?

The biggest reason to choose secondary metering over primary metering is the ability to monitor the usage of each transformer. This alerts you to problems early on that can be fixed before they get too big. This can also help if you are a landlord over an apartment complex. You can make sure that everyone is paying their fair share of the electricity by having them pay their own bills.

Conclusion

Primary metering and secondary metering are both good ways to meter a customer’s service. They are two different approaches to the same problem. You can meter a large industrial customer with primary metering equipment even though they may have ten different transformers on their site. You could also meter those ten transformers with secondary meter and come out the same. If you want to learn more about CT meters, our readers have found CT Meters: Understanding Current Transformer Meters and Their Applications to be helpful.








CT Meters: Understanding Current Transformer Meters and Their Applications

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CT meters, or current transformer meters, are essential for measuring electrical consumption in large-scale systems where direct metering is impractical. Typically used in commercial and industrial settings, CT meters work in conjunction with current transformers (CTs) to provide accurate measurements. Understanding how to calculate CT ratios and multipliers is crucial for ensuring accurate billing and system monitoring.

What is a CT meter?

A CT meter is simply a meter that is used in conjunction with instrument transformers known as current transformers. These are also known as CTs. In electrical metering, meters are divided into two types. There are self-contained meters. In addition there are transformer-rated meters. Transformer-rated meters are also known as CT meters.

What are the characteristics of a CT meter?

The characteristics of a CT meter include its ratings. CT meters now are generally rated at 20 amps. This means that the current coils of the meter are capable of handling 20 amps. You may think that this is low. But, remember that CT meters are used with CTs. Also remember that CTs have outputs determined by their ratios. They are rated with an output on the secondary side of 5 amps. If you remember, when using the rating factor of a CT it is possible for the CT to put out 20 amps.

CT meters also have voltage ratings. Many of the meters now are multi-range. This means that the meter can sense the incoming voltage and adjust its calculations based on the incoming voltage. Most meters now show the voltage on the display. Before digital meters, one had to be careful to make sure that the meter with the correct voltage rating was chosen.

What types of CT meters are there?

When talking about meter types what we are really referring to are the meter forms. Meter form numbers are used to designate what type of meter we have. These meter form numbers help us to decide which meter to use in which installation based on Blondel’s Theorem.

The normal transformer-rated meter forms are as follows:

Form 3s

Form 4s

Form 5s

Form 9s

Now remember that these are the most common. There are more.








Where will you find CT meters?

CT meters are installed on services that are too large for self-contained services. This normally means services that are larger than 200 amps. Although there are now self-contained 320 amp meters as well as 400 amp bolt in meters. CT meters are also used whenever PTs, potential transformers, are used to step down the voltage.

Large residences, commercial and industrial buildings, hospitals and schools are all examples of where you will find a CT meter installed.

Troubleshooting Common Issues with CT Meters

Troubleshooting CT meters often begins with identifying discrepancies in meter readings compared to expected values or other monitoring equipment. One common issue is incorrect readings caused by improper installation of current transformers (CTs). For example, if the CT polarity is reversed—where the primary and secondary markings (H1, H2) or (X1, X2) are incorrectly aligned—the meter may display negative power readings or incorrect energy consumption values. Verifying that the CT orientation matches the system’s design is crucial during the installation or inspection process.

Another frequent issue arises from incorrect CT ratios being programmed into the meter. A mismatch between the actual CT ratio (e.g., 400:5) and the ratio configured in the meter will result in inaccurate multipliers and billing errors. This can be resolved by cross-checking the physical CT labels with the meter’s programmed settings and making adjustments as needed. Additionally, loose or corroded wiring connections between the CTs and the meter can disrupt signal integrity, leading to inconsistent readings. Inspecting and securing connections regularly is essential for maintaining accuracy.

In high-load environments, overloaded CTs can also pose a problem. While CTs are designed to operate within specific ranges, exceeding their rating factor can result in saturation, where the CT no longer accurately reproduces the primary current on the secondary side. This typically manifests as distorted or limited readings at higher loads. To address this, ensure that the selected CTs are appropriately rated for the system’s maximum load, considering any potential surges. Regular testing and calibration of both CTs and meters are recommended to prevent and address these issues, ensuring reliable system performance.

Conclusion

CT meters play a vital role in accurately measuring electrical consumption in large-scale systems where direct metering is impractical. Their use in conjunction with current transformers allows for safe and precise monitoring of high-voltage and high-current environments, making them indispensable in commercial, industrial, and utility applications. Understanding the basics of CT ratios, meter forms, and installation practices is essential for ensuring accurate billing and reliable system operation.

By addressing common issues such as improper installation, incorrect ratio programming, and wiring faults, users can maintain the integrity of their metering systems. Regular testing, maintenance, and an awareness of advancements in metering technology can further enhance the reliability and efficiency of CT meters. As the electrical industry continues to evolve, CT meters remain a cornerstone of accurate energy measurement and system monitoring, ensuring the seamless operation of modern power systems.








Prepaid Metering

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Prepaid metering is a way that both customers and utilities can benefit from the technological advances in metering that have been made in recent years. When it comes to paying for electricity it seems that the electric industry has fallen behind the rest of the retail world. Electric utilities allow customers to use their service and then at the end of the month calculate how much each customer used and then sends them a bill. This has worked well almost since the first electric bills were sent out. However, with post-pay when customers cannot afford to pay their bills they end up working out arrangements with the utility to pay at a later date. Also, some customers decide that they need to move and they do not think that they need to pay their final bills.

If only there were a way to change some of this. But there is. Prepaid metering is a way that utilities can collect the money from their services up front.

Prepaid Metering Is Good For Customers

There are several advantages that prepaid metering has to the traditional way of billing. One being that payments are collected before the customer uses the power. Just like a prepaid phone service, when the purchased time runs out, the service stops. With smart meters now including remote disconnect devices the utility can monitor the usage from the office. This allows the utility to turn the power off to customers when their purchased kwh time runs out.

Some people will cry foul here and say that it is unfair to the customer to be turned off without notice. But, the companies who offer this service provide customers with text an email alerts notifying them that they need to pay or be turned off. Many of these services offer the ability to pay from the customer’s smartphone.








In addition to being able to pay their bills from their smartphones, customer can purchase blocks of power. Customers can purchase what they can afford at the time to keep the lights on. This is beneficial to many customers who may not have the money to pay a $300 light bill at the end of the month. They may only have $50 to get them through the next few days. This ensures that they do not lose service.

Customers also have the added benefit of an online portal where they can monitor their usage. They can keep up to date with the amount of power that they are using as well as the amount of power they have left. Many studies show that customers who are on prepaid rates are more conservative with their energy usage.

Prepaid Metering Is Good For The Utility

Prepaid metering allows the utility to reduce its bad debt expense. The bad debt is debt that is written off because it will never be collected. This can be due to customers leaving without paying or customers who cannot afford to pay and change the name on the account. What happens is the utility ends up being a lender of sorts. When a customer does not pay the utility often gives them a grace period. All the while the customer is using more and more power. Their bill is getting higher and higher.

The utility eliminates some of its bad debt by collecting up front. If the customer decides to leave the utility reimburses, depending on the rate, the customer. This can be good for utilities who have meters in high turnover areas such as college towns, and apartment complexes.

One way to implement this would be to offer it on a voluntary basis. This is where customers sign up voluntarily. Another way is to start with new customers. Still yet, using credit checks is another.

Conclusion

Prepaid metering is not for everyone. But there are instances in which it is perfect for some. Utilities should examine whether it is beneficial to both the bottom line and the customer. Customers should view prepaid metering with an open mind and look at the potential benefits it offers them.








Time of Use

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Time of use is a metering concept based around changing your usage behavior to not only lower your costs, but the costs of the utility as well. What is time of use? How can you take advantage and benefit from time of use? How does the utility benefit from time of use? These are three important questions that surround the time of use concept.

What is time of use?

Time of use is actually a very simple concept. Utilities use on peak periods and off peak periods. On peak periods are those periods during which the utility normally hits their peak. This is defined as a time period. For instance, the on peak period could be from 2pm – 5pm, Monday – Friday. In this example, the off peak periods would be everything outside 2pm – 5pm, Monday – Friday. Or, the periods of time in which the utility does not peak.

These time periods are typically have names with letters such as, period A or B. The electric meters are programmed with these time periods. Typically these meters have more than one register reading that is displayed. The readings that are displayed are for the different time periods.

In a time of use rate, on peak and off peak prices are different. On peak prices are more expensive than off peak prices. This is to encourage businesses and even some individuals to change their usage during these times. Which leads to the next point.








How can you take advantage and benefit from Time of Use?

To take advantage of time of use and reap all of the benefits you need to do a study of your usage. Some utilities will provide you with this service free of charge. They will install a load profile meter (often called a load survey meter). After a few months you can view the data. The data lets you know what times during the day you use the most power. Armed with this information you can make decisions about the available time of use rates offered by your utility.

It may be that you can come in an hour earlier to avoid hitting that peak. Or maybe completing some of your processes in the morning instead of the afternoon. The data lets you know.

Time of use offers a discount during off peak times. This is where the big advantage lies. New industries like crypto mining can benefit from TOU rates. Compare the prices of on peak versus off peak for the rates at your utility. You can save big. But beware, once your are on a time of use rate usage during the on peak time are higher.

How does the Utility benefit from Time of Use?

The utility benefits by being able to shift some load to off peak times. Looking at the utility’s consumption on a line graph shows when they peak. The normal line graph has peaks and valleys. They too are billed on the peak. Or if they generate their own power when the peaks are high they have to bump up their generation. Ideally, looking at a line graph, a utility wants their line to be straight. This means that the generation is constant. Moving some customers from on peak periods to off peak periods is one way of achieving this. The utility benefits from the lower cost of generation or price and passes that on to the customer.

In conclusion, time of use is a rate structure that is comprised of on peak and off peak time periods. It can be a great way for customers to lower their bill by shifting some of their normal routines. Utilities benefit by being able to shift some of their on peak load to off peak times thus reducing their overall demand costs as well.









Totalizing Meter Readings

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Totalizing meter readings can be a very effective way to lower your demand and KWH costs. So, if you are a commercial or industrial customer and have multiple meters you may benefit from totalizing your meter readings. What is totalizing? How can you benefit from totalizing? What are the different methods of totalizing?

What is totalizing?

Totalizing, at its simplest form is nothing more than addition. You take the meter readings from all of the meters that you have and you add them together. This, in turn, gives you one meter reading. Furthermore, it is much easier many times for the customer as they only have to keep up with one bill. A more advanced definition of totalizing is that by combining your meter readings the peak demand can be effectively reduced.

To explain this we need an example. Look at the picture below. In it you see that there are three lines. In this example we have meter A, B and totalized meter C. Also note that the numbers on the bottom are hours of the day. Here we are assuming that the demand interval is hourly. Notice that meter A peaks at 3:00 PM. The peak demand for meter A is 24 KW. Notice that the peak demand for meter B is also 24 KW but it occurs at 9:00 AM. If you do not remember how demand works go over to my page on demand for a better understanding.

.totalizing chart




Now that you have seen where meters A and B peak, let’s look at the totalizing meter C. Meter C peaks at 12:00 PM with a peak of 19.5 KW. This is 4.5 KW less than both meter A and meter B. This is because the totalizer effectively averages out all of its inputs. With KWH totalizing simply adds all of the KWH readings of the meters.

How can you benefit from totalizing?

Well, using the example above I am sure that you can see that your demand is reduced. So, let’s put that into dollars. Assume that your per KW demand charge is $15.00. For each meter that you have, A and B you will pay $360 each (24 KW x 15). So, for both meters you pay $720 per month just in demand charges. In addition, if you totalize with meter C your demand charges would only be $292.50 (19.5 KW x 15). A savings of $427.50! This is huge! However, remember that this is just an example, it is exaggerated.

You also save with your KWH charges. The reason for this is that most rates are tiered. Meaning that the price changes as you use more KWH. Also, in most cases the price goes down. If meter A uses 10,000 KWH in a month and meter B uses 15,000 KWH in month then in total they use 25,000 KWH. However, if the price buckets are as follows:

  • $0.10 for the first 5,000 KWH
  • $0.08 for the next 10,000 KWH
  • $0.06 for all over 15,000 KWH

then if your meters are billed separately you will not be able to take advantage of the cheaper rate bucket. If you totalize however you will be able to take advantage and save on your KWH as well.

What are the different methods of totalizing?

There are two main methods of totalizing. Totalizing with software is the first. Using hardware, such as the meter is the second. To totalize with software the utility downloads readings from each of the meters that are to be totalized. The utility then uploads the readings to a totalizing program. This program looks at all of the readings adds them together and averages them out. Then it gives you the totalized readings.

Using hardware to totalize is a bit different. Wires are run from the meters that need to be totalized. Then to a central meter that totalizes the readings internally. The utility then reads this totalized meter to get the readings. Finally, the utility bills the customer with the totalized readings.

Final Thoughts

Although it sounds like totalizing is definitely worth it you need to be aware that your utility may charge a premium to totalize your readings. This can vary and also may not be worth it. Instead of paying facility charges for the meters that you already have, you may pay for those and the totalizer. In addition, totalizing meters are expensive.

It is best to talk with your utility to determine if you are a good candidate for totalizing.








Computers and the Meter Tech

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As a Meter Technicians a computer will be very useful in your job. Many tasks in the metering world are not possible without the use of a computer. You can use a computer to help you with troubleshooting and performing load checks. Because of the this meter techs will need to know how to use different programs. They will also need to know how to analyze data.

Programming meters as a meter tech is an easy streamlined process. Many of the meter manufacturers have easy to use programming software. Once the program is built all you need to do is connect the probe to the meter. Then click the program and go through the prompt. Building the program can be tricky for those who do not know their way around a computer. If you need to change variables you need to know what the changes will do in the program.

Outside of programming meters, meter techs will need to be able to use Microsoft Word and Excel. Word is not used as much as Excel but is good to know. Many tasks can be completed with Excel. However, it will mostly be used to view data. At times data will also be exported to Excel. At other times data will need to be calculated in Excel. You can also use Excel as a small database for things such as test sites, or new installations. Meter techs also use Excel to view .CSV files and bill details.








One of the most important uses of the computer to the meter tech is billing system. Here the meter tech will look up the details of customer bills when talking to customers about their high bill complaints. It is important to know how to use this system and use it effectively. There are typically historical comments where other techs may have gone out before you. Also, you may find out that this is a problem customer. If that is the case you will know that you need to be on your game. This means meeting the customer with all of the facts.

In the billing system, meter techs will also assign multipliers to meters. This is very important. An incorrect multiplier in the billing system is one of the easiest mistakes to make. Especially if you have just completed a new installation. Billing systems are typically good at kicking out readings that appear to high or too low. And if a meter was just changed and the incorrect multiplier for that particular meter was put in the system it will generally get kicked out. However, with at new installation the computer has no history of that location to go on. Noticing this error could take years. Furthermore, this could be in the customer’s favor or in the favor of the utility.

In conclusion, being a meter tech is more that just going out in the field and swapping out meters. You need to have a good grasp on technology. Computers are essential to meter techs. The sooner you can master at least the basics the better.