Advanced Energy Management 

Extending CT wiring for Muichannels Meters

Kelly Reiser

Warning - The advice here is given with no representation of fitness. In all cases your meter manufacturer should be consulted on the proper method of extending CT wiring. 

Current Transformer (CT) Wire Extension

Extending the CT leads adds resistance (burden) to the current circuit, it is important to minimize the amount of resistance in the wiring so that accuracy is maintained  Degradation of accuracy will increase as the wire run get longer and if splice connections are poorly made. Meter manufacturer will accept no responsibility for this degradation of accuracy and typically recommends that a current reading verification be completed to validate accuracy of readings in the case of all extended wiring.  

Overview

While the manufacturer will  recommend that CT wiring not be extended there are occasions when longer current transformer (CT) lead wires are needed. If the standard leads are not long enough, they can be extended to 100 feet (30 m) or more, especially if you keep the wires away from electrically noisy equipment (variable speed drives, fluorescent lighting, etc.). To minimize power line noise from interfering with sensitive CT signals, extension wires should be run in conduit separate from power conductors and other electrical circuits.

The most common practice is to extend the lead in the field using 18 AWG twisted pair wire. You can find 18 gauge twisted pair wiring from your local distributor in both shielded and unshielded varieties.

If you want to extend your CT leads, the typical recommendation is one of the following options:

 - Twisted – This is the recommended solution for CT extensions, standard black and white 18-gauge CT leads are twisted. The twisted pairs help increase noise immunity.  

 - Shielded and twisted – Adding a shield will offer some additional noise immunity, especially for long extensions. It is important that the shield be connected to ground at both ends of the extension to provide the best immunity.  It is also important to note that in all cases the shield cable should also be in the twisted pair configuration. 

Unshielded

Standard CT wires are unshielded but have good noise rejection due to the twisting of the wires. Standard twisted black and white 18-gauge wires are available in various size coils. 

A few recommendations for  current transformer wire are as follows. 

Manufacturer: Alpha Wire

Reel Length: 100ft

Web: Alpha Wire - Newark

Part #: 5606B1801 BK005

Manufacturer: Belden

Reel Length: 1000ft

Web: Belden - Newark

Part #: 9486 0101000

These each come with the following specifications: 18 AWG, Stranded, Twisted pair, 600V, RoHS.

Shielded

CT signals are susceptible to interference, magnetically and capacitively induced into the wires. The twisted-pairs block most magnetically coupled and differential noise, but does not reject common-mode, capacitively coupled noise. A shield can help block common-mode capacitively coupled noise but is most effective if both ends are grounded. If only one end is grounded, the ungrounded end will oscillate up and down with the interfering signal, and then couple into the twisted pair wires.

Cable is typically available in 300- and 600-volt ratings. Most meter manufacturers recommends that 600 V rated cable be used for all CT extensions.

In three phase applications to cut down on the number of cables to run, a jacketed cable with three twisted pairs and an overall shield can be used. We recommend no more than three pairs per cable.

Since standard CT wires are typically 18 AWG, we recommend extending with 18 AWG or larger cables. If you are using UL listed CTs, then you must use a matching wire gauge to that of the CT itself for any extension to preserve the UL listing

Manufacturer: Carol Cable

Reel Length: 1000ft

Web: Carol Cable - Newark

Part #: C2536A.41.10

Manufacturer: Belden

Reel Length: 1000ft

Web: Belden - Newark

Part #: 9341 0101000

Splicing

When the lead wires on standard stock CTs are not long enough, you can extend them by splicing on additional wire. The following recommendations will result in the most trouble free installation.

 - Avoid separation or large loops between the white and black wires as this can increase electrical interference.

 - Wire-nuts can be used only if they are rated for connecting the stranded #18 AWG CTs wires, to the extension wire. To ensure reliable connections, be sure to follow the manufacturer’s instructions.

 - Butt splices and other styles of crimp connections work well if the proper ratcheting crimping tool for the connector is used. Caution!: general purpose crimping tools do not always make reliable connections. After crimping, tug on the wires to make sure that they do not pull out of the crimp.

 - The most reliable and recommended connection type is a soldered connection with heat shrink tubing insulation.

Notes on Crosstalk and Interference

It is common to question how much loss in accuracy or error will be introduced by extending your CT wiring leads. There is no specific answer to this as there are variables that change in each and every case. Various building and wiring conditions will affect the amount of accuracy loss

In the case of crosstalk, the amount of crosstalk depends on the following:

 - Signal frequencies: if your load has strong harmonics, there could be more crosstalk.

 - Cable properties: such as capacitive and inductive coupling between adjacent conductors.

 - CT source impedance: different current transformers have different winding resistances and internal burden resistors, resulting in different source impedances and different susceptibilities to interference and crosstalk.

 - Cable length: the longer the cable, the more crosstalk.

 - -Signals on different CTs: are you monitoring a balanced three-phase load or are there completely different current signals on different CT cables?

Many of these variables are unknown and their interactions with each other are difficult to predict. With the recommended cable types (twisted pair or shielded), properly installed, crosstalk should be negligible. With other cables, it is impossible to predict if crosstalk will significantly affect the accuracy.

Interference is also impossible to accurately predict or quantify, because it depends on all the factors for crosstalk, as well as the amplitude and frequency of the interference, the distance from the source of the interference, and external shielding, such as conduit.

In our experience, it is easier to avoid long CT lead extensions but if longer CT wiring is required make sure to use high quality cable with proper splices to avoid complications.

Green Game Plan

Inspiring a sustainable culture at a school or university.

Kenner B. Kingston, Bill Wilson, Brian Cassil | Oct 19, 2017

Today’s education marketplace expects that green buildings will automatically use less energy, be more healthful, and create less waste. Not true. Why? This expectation overlooks the critical impact of the people who occupy a building.

A sustainable building is only as successful as the culture of its occupants.

The culture of a place, including a school or university, is rooted in a set of values, beliefs, and habits shared by a group. Culture also includes the relationships formed around a shared mission. Campuses that invest in programs such as LEED certification or other energy conservation strategies are often surprised that they haven’t reached the desired outcomes. This is largely because occupancy is a core driver of building performance.

The key to effective change is to empower people to make sustainability a part of their everyday lives. Because of greater levels of transparency and greater opportunity for collaboration, people can connect and engage in ways previously unimaginable. This has created challenges as well as opportunities. The shift in culture, as it pertains to sustainable buildings, requires occupants to change their thinking and shift their habits to align with the larger goals. Change depends on the local context and on an individual’s reasons for taking part. Participants want to know that the effort they invest will have positive outcomes, regardless of the type of recognition they receive as a result.

Performance measures also matter, but what is at the core of participation is the intangible sense of making a difference. Oscar Wilde described a cynic as someone “who knows the price of everything and the value of nothing.” To avoid such cynicism, school administrators should focus on not only the quantifiable data, but also those elements that are harder to measure but are equally if not more important. Although the culture of sustainable design can be data-driven, data represents only a part of a larger perspective that leads to positive, effective change. When both elements – quantifiable and intangible – synthesize, a successful paradigm shift occurs, and desired outcomes follow.

Innovation is most successful when it responds to local culture. If students, faculty, and staff believe that their contributions will yield a desired collective outcome, they are more likely to participate. If they hear from their peers, they are more likely to listen.

A willingness to tailor strategies for change to local practices helps ensure adoption and enables groups to tolerate future culture shift and disruption. It is not a building alone or a set of guidelines that will reduce energy use; rather it is the ability of participants to adapt their behavior to a set of shared goals.

Architectural Nexus, Inc.

Tracking energy usage is just one way to commit to sustainability.

Setting Goals

Setting specific, measurable goals can inspire the interest and engagement needed to promote a culture shift on campus. The goal-setting process offers a chance to choose major themes around sustainability, such as energy, water, transportation, food, and waste, and to develop a calendar of priorities.

From the beginning, one message has to be delivered: all goals will be meaningless unless participants believe that they can move the needle in a positive direction. There may be incentives and recognition, but in the end, people want to know that their actions have an impact.

Leadership and Internal Champions

For an occupant engagement program to be successful, facility planners must identify individuals who believe their actions can positively affect sustainable performance metrics. Internal champions with a passion for sustainable causes can make compelling spokespeople. Cultural change won’t happen without them, so it is vital to enlist such champions early on.

The connection between leadership and the internal champions keeps participation going, and provides a natural feedback loop between the front lines of the student population and all levels of university governance and operations. An internal champion encourage participation and remind people of what can be accomplished within a short period of time.

Even more important than a champion within the student body is support from university leadership. When all parts of the school populace work with one another, a new initiative can run smoothly, and a culture shift can take hold. With support from leaders, it is easier to get the word out around campus and into the classroom through advertisements or as part of the curriculum. Influence from leaders makes it easier to bring about changes in the behaviors of students, faculty and staff.

Participation

Strong messaging, initiatives and incentives help shift entrenched habits and beliefs. Gamifying participation—e.g., adding a fun, competitive element that makes the process more like a game—can foster enthusiasm and boost participation. Support these efforts by educating campus populations about sustainability best practices.

Timing is important. Try to synchronize activities with the academic calendar. If a program runs too long or starts too close to the beginning of a term, people may be inclined to ignore it. The rhythm of campus life is best suited to increments of four to six weeks. This is long enough to help participants develop new habits, but short enough to keep the goal in sight. Building and promoting a program for busy people with a commitment of as little as five minutes per week can dispel the myth that there isn’t enough time to contribute.

Architectural Nexus, Inc.

InHabit is a program developed as a partnership between Sustain3 and Architectural Nexus to address occupant engagement for energy conservation and other sustainable initiatives on campuses.

Communications

Students and educators are bombarded with information and appeals. Short, concise, content delivered and repeated through diverse media channels ensures that a message will not be lost. Even so, face-to-face communication is more effective than social media. When an acquaintance, friend, or colleague shares information and enthusiasm, an individual is more likely to be won over.

On campus, engagement programs need to incorporate compelling stories and strong illustrations. Getting people to embrace sustainability starts a conversation loop, no matter what the focus is. Why should I buy a Prius? How do I compost eggshells or install a sustainable floor at home? Pushing out new content reinforces the discussion.

Graphics can go a long way to convey information. People are much more likely to respond to messaging that is visually stimulating.

An equally vital component is varying how one communicates. Faculty and staff may still read emails, but students are more likely use Snapchat, Instagram, Facebook, Twitter, or text messaging. A cloud-based platform that leverages many media channels with repeated and persistent messaging always wins out. The more closely associated a message is with the team—and with its interests and goals—the more likely it is to resonate.

Taking the pulse of a school—understanding its culture, and identifying established associations and linkages—is perhaps the most nuanced part of the process, but it is the most critical. Defining the places where people interact produces strong associations. Inviting competition between residence halls, grade levels, or other friendly rivals can inspire comradery and participation.

Challenges and Rewards

After the initial goals and metrics are identified, schools need to find ways for engagement to take hold. Gamification may involve developing ideas for challenges and creating the types of rewards and prizes that will resonate with the culture of the campus. Posting team results during competitions helps incentivize continued participation and sparks curiosity among non-participants that may pay off later.

Rewards such as gift cards can also incentivize participation. Alternatively, tying results to specific social causes can serve as an incentive while nurturing a sense of philanthropic purpose. For example, a percentage of a purchase of one item may go to clean water in Africa, and another may contribute to building a school in India.

Of course, some cultures are not conducive to team competition, and it is important to determine this before deciding what incentive to use. In these situations, it works better to invite participation and ask for volunteers.

Measuring Goals and Assessing Efficacy

A successful sustainability engagement program, one that moves groups of people toward a more sustainable culture, must find the right mix of participants and actively involve them. But it is equally important to measure the impact. Although it is difficult to quantify the less tangible goals of long-term sustainability or of improving the quality of life of a community, it is possible to rank how participants see their own engagement and efficacy. Readings from electric and water meters, utility bills, transportation surveys, waste stream audits, and other methods of measuring performance metrics are critical to demonstrating how people’s actions have a tangible impact on moving the needle.

Cloud-based enterprise software has distinct advantages for many different industries

Finding ways to make any facility more energy efficient used to be about making sure everyone knew to turn off equipment and lights after they left the room or shut down for the day. Today’s building manager understands the ability to drill deep with innovative new solutions that involve hardware and software and the latest in energy analytics. With the latest technology, it is economically feasible to find the causes of lost energy, as these go well beyond changing wasteful light bulbs or replacing old, inefficient heating systems. Today, energy waste can be pinpointed with accuracy using technology that has sprung from modern IT solutions.

Real time energy management (RTEM) solutions take on what’s commonly referred to as energy drift as part of an overall focus on the sources of waste, such as those associated with HVAC components that are in need of repair or maintenance. The real-time information provided by today’s cloud-based software can actually pinpoint issues and problems that might otherwise be overlooked like improper control system programming.

Cloud-based Software

Cloud-based enterprise software has distinct advantages for many different industries. The value and benefits that RTEM technology and services unleash can lead to 30 percent savings in energy costs, as well as savings in the life cycle cost of many types of equipment and systems. The key to all of this technology is the ability to acquire and install the equipment at a low cost.

Cloud-based solutions are scalable, and are generally widely accessible, and in energy applications, are often populated by data sent by submeters that are independent of each other. This means that you benefit from a simpler and lower cost installation, and can avoid the IT infrastructure and staff costs required to operate and maintain the data and systems. That means you pay only for the incremental cost of a central system, and this can lower overall costs to the point that a service can become economic.

With cloud-based systems lowering the overall cost of software and data services, and newly designed submetering hardware lowering the cost to collect the data, advanced energy management practices can be justified. When a facility uses only the energy that’s required, while lowering the associated carbon footprint, RTEM begins to make good business sense. In emerging business environments where cap and trade and carbon pricing are becoming the norm rather than the exception, the financial incentives to implement RTEM solutions make going green from top to bottom, even more attractive.

Big Data & Information Security

The cloud is the most secure and economic way to store large amounts of data and have that data available to fuel ongoing analytic functions. When it comes to the real-time amalgamation of all energy data usage for a single facility or an entire portfolio, there is a powerful trend towards software that is cloud-based.

The many advantages of the cloud, combined with the power of Big Data, has resulted in a strong trend in leading technologies to base their value on the exploitation of these two pillars. Those enterprises that intend to pursue the benefits of Real Time Energy Management will inevitably find that the economics and functionality of their alternatives are driven by these two elements. Having the ability to scale up or down with enterprise software that addresses the needs of portfolio managers, means that you can focus and pinpoint on the areas that need the most attention when it comes to energy efficiency. Battling energy drift with real-time energy management solutions means finding answers through the cloud.