Remote monitoring closes the gap between meters and breakers
Power management solutions – hardware metering devices, protective relays, communications components and software – enable end users to monitor, analyze, diagnose and control their power distribution systems from across the room or across the world. Remote monitoring helps plant managers make informed decisions about operational efficiency, system reliability, employee safety and en...
Power management solutions — hardware metering devices, protective relays, communications components and software — enable end users to monitor, analyze, diagnose and control their power distribution systems from across the room or across the world. Remote monitoring helps plant managers make informed decisions about operational efficiency, system reliability, employee safety and energy costs.
But when it comes to a manufacturing facility’s electrical system, remote monitoring should be approached thoughtfully. Information needs must be balanced against the cost of the solution. Affordable enabling technologies allow end users to benefit from including remote monitoring in their power management strategies.
Remote monitoring extends beyond low-voltage switchgear to MCCs, circuit breakers, feeders, tie breakers, transformers, busway, panelboards — anything in the plant’s electrical distribution system. “All electrical equipment can be monitored,” said Jane Barber, product manager, GE Consumer & Industrial. “It’s a matter of having sensors fed to devices monitoring the necessary parameters. Each type of equipment has sensors and devices suited specifically to the application facilitating remote communication.”
Barber said sensors for current and voltage provide the basic input to devices used for protection and/or metering and monitoring, as well as status of the power system. Intelligent remote monitoring and power management systems use voltage, current, status and temperature to derive hundreds of useful parameters to help plant managers stay on top of what their electrical systems are doing.
“There are various levels of monitoring,” Barber noted. “There is the basic monitoring of current, voltage and possibly other conditions such as temperature. Another level of sophistication is the ability to monitor and report the actions of protective devices. Consequently, this level requires more intelligence at the protective device level.”
Why remote monitoring?
Reasons for monitoring a facility’s electrical system range from voltage, current and status indications, to integrated power and automation systems, alarm management capabilities and real-time analysis of energy usage. Brandon Ekberg, business manager for software and meters for Eaton Corp. said there are three reasons for remotely monitoring a power system.
“The first is state change such as breaker trips, or bus status — the ‘what’ of the electrical system. The second is the ‘why.’ What’s going on with the electrical system? If a breaker trips, why did it trip? Is it a nuisance or is there a trend behind what’s going on? Are we approaching capacity? A trip could be set at 100 A, but the current is 80 A. It doesn’t trip, but that section typically runs at 50 A. This is a significant difference. A power management system with remote monitoring capabilities can track these trends and notify operators and engineers before a problem becomes a real crisis.
“The third is the ability to understand capacity and energy consumption,” Ekberg said. “How will the installation of new equipment affect the electrical power system? Is there enough capacity? Will new electrical infrastructure be required to accommodate the new equipment? Will more efficient use of resources and energy negate the need to install new equipment? These and other power management questions can be answered by remote monitoring of what’s going on out there in the plant.”
Remote power system monitoring also extends to more complex applications. Quantifying energy use enables facilities to employ load shedding and peak shaving initiatives for energy cost savings. “In order to meet utility curtailment rate agreement peak demand limits, non-essential loads are automatically disconnected until the target limit is reached,” said Robert Kennedy, director of product management at Square D Engineering Services, Schneider Electric. “Alternatively, backup generation is brought online automatically to reduce peak demand seen by the utility — without shutting loads.”
Chuck Miller, solution design manager for Johnson Controls, said there are two ways for end users to reduce their energy spending. “One is you procure it cheaper; the other is you use less of it. Either one of those requires information on how much you use, how much you actually need and what are the systems in your plant that need the most of it.”
Many manufacturers don’t know which part of their operation is the most energy-intensive because they don’t use sub-metering. “With the advent of new wireless technologies, you ought to be taking advantage of the infrastructure that you already have in place because it’s just adding new points,” Miller said. “You put a sub-meter on; you put a flowmeter on; you put an electrical meter on; and you see where energy is being used in your process.”
A relatively new application that takes advantage of remote monitoring and automatic controls involves automatic testing and reporting for emergency power supply systems — for example, backup generators. In critical power applications, various standards such as NFPA require periodic testing of backup generation according to prescribed load levels and durations.
“In some cases, documentation is required to prove that the proper tests were performed in the required timeframe,” said Kennedy. “In the past, this was initiated manually and records were kept on paper. Ensuring adherence to minimum load levels was difficult. If not performed correctly, more harm than good could be done to the generator. With pre-defined, automatic logic to ensure adequate load levels for the required duration (typically 30% load for 30 minutes), and automatic test reports to document the successful testing, this task is greatly simplified.”
PLCs have been used for years to operate simple automatic controls in electrical distribution equipment. For example, PLCs have long facilitated automatic transfer to standby or emergency power. Building automation systems control lighting zones based on shift, time or room/section occupancy sensing. Circuit breaker auxiliary contacts enable remote power monitoring systems to detect breaker status. A simple signal to a breaker’s trip coil is all that’s needed to turn the lights off in an unused section of the plant.
Measurement necessarily comes before management. Hardware, software and communication elements work together to bring diverse power components into a unified system that can be monitored and managed effectively. “The intelligence gap between meters and breakers is closing every year,” said Ekberg. “All these devices — switchgear, MCCs, feeders, all the way down to the circuit breaker — are becoming more intelligent. Even with breakers, by sensing voltage, current and status, intelligent, microprocessor-based equipment can determine hundreds of useful electrical parameters — including power quality — to help operators and plant engineers make better manufacturing decisions quicker.
“Walk-around inspections can now be done virtually, enabling plant personnel to monitor more in less time,” Ekberg said. “It’s also safer. Monitoring from a distance keeps people away from areas where an arc flash could happen.”
Just as voltage, current, status and temperature are the basic measurements from which more complex parameters are derived, the traditional ways to capture data include trip units, meters and relays. “All of these devices can communicate over various communication protocols to remote monitoring systems,” said Barber. “Progress has been made in technology to enable intelligent systems to provide holistic protection, control and monitoring for the entire lineup. This type of architecture not only provides advances in circuit protection and selectivity, but also streamlines the communication architecture by needing just one communication connection to monitor the entire system, providing a holistic, coordinated status of all switchgear conditions and records instead of a connection for each individual device and singular status and event records.”
Ethernet and Web servers embedded in switchgear, switchboards, panelboards and MCCs allow simple and affordable access to energy usage and operational data. Most modern low-voltage switchgear incorporates data communications for connection to a plant-wide LAN. Kennedy estimates that more than 80% of his company’s low-voltage switchgear includes Ethernet connectivity. Common Ethernet networking accessories such as routers, switches and Web servers are shared by both power and automation systems.
Open and easily deployed network solutions put electrical power system monitoring technology within reach of more end users. “In the past 10 years, Ethernet has emerged as the standard for LANs, including power for the facility and automation to the plant floor,” Kennedy said. “In the past five years, Web technologies such as http, FTP and XML have simplified data access, facilitated interoperability and allowed much tighter integration of automation and power products. Also over the past five years, plant engineers have begun to expect more than standard metering products alone, giving rise to customized solutions such as emergency power supply system testing and reporting applications.”
“Remote monitoring of status is beneficial,” said Ekberg. “But monitoring power quality parameters can give manufacturers insight into their processes.”
Top nine PQ problems
Data show that the reliability of a power system may be three to five times worse than the original design if a system is poorly maintained. It’s important to recognize the nine most common power problems present in any environment. They include:
It is almost impossible to name an industry or business sector in which power reliability is not now a critical need. To stay up and running, critical systems and infrastructures require constant monitoring and vigilant management. Monitoring and data analysi
— conducted on site or remotely
— provide instant visibility, isolating problems and their causes so they may be resolved quickly.
Remote monitoring also has become more cost-effective, thanks to the Internet and to relatively low-cost wireless communications. In some remote monitoring configurations, when sensors detect problems or anomalies, they automatically generate an alert message. Companies have the choice of self-monitoring their equipment or of tapping the resources of a provider, which has the capability of flagging and authenticating data sent from any location across the globe, evaluating it and then notifying the company and/or automatically dispatching technicians.
Monitoring can identify abnormal conditions within the entire electrical power system as they develop, before a failure or significant damage can occur.