Connectivity and power monitoring unite in the fight against downtime.
Today, reducing electrical downtime often involves remote monitoring and control. Electrical power monitoring and control systems (PMCS) can alert you to trouble remotely, not just via an audible alarm or flashing light on-site. Thus, you can access information and address the problem - without ever having to visit your facility!
Most PMCS components are evolutionary improvements to meters, trip units, software, and similar items you are probably familiar with. What's new is their connectivity - their ability to alert you at home via a pop-up window or e-mail on your computer, or via a signal to your pager. These items are merging with other familiar technologies, such as data networks and cell phones.
Once notified, you can access detailed real-time and historical information to find and eliminate the cause of the condition that triggered the alarm. You can do so from your operation center, hotel room, home, or almost any where else you have access to a PC and a phone line or Internet connection (wireless or otherwise). If your system has automatic control capabilities, it can immediately take steps to restore power and preserve loads - while you're still analyzing the problems. As you might imagine, this means an extremely rapid response and recovery time.
While the concepts behind such a system may seem simple, the way in which they are the executed varies from system to system. Some systems are well-engineered and highly functional, but others are patchworks of components that stretch the ability of software to glue them together. Some work well within a fairly narrow scope; others are more flexible.
What is a "narrow scope"? In some cases, the system has a rigid design the end-user can't adapt to site-specific needs. In other cases, the system has a dedicated purpose. For example, you can buy a remote generator monitoring system dedicated to that purpose alone (see Sidebar).
Differences abound in the level of offerings that go with the remote-monitoring system. Some systems offer an array of integration and analytical services to help you leverage your investment. With other systems, you provide that expertise yourself. Which is more cost-effective depends on your needs and resources. The Sidebar shows key items to consider when specifying a system.
Remote alarms. Two distinctions highlight the differences between available systems. One is the granularity with which a system can detect alarm conditions. All PMCSs have circuit-monitoring devices that can alarm on larger 3-phase feeds. However, relatively few PMCSs have economical options for alarming on overloaded 15A branch circuits.
The other distinction is the degree to which a PMCS can extract useful troubleshooting information from the electrical distribution system. For example, most PMCSs can sense power circuit breaker position. The better-integrated systems can also show the cause of trip, current at trip, and contact wear.
Communications and connectivity. If the PMCS uses open standards, such as Ethernet, TCP/IP, and Modbus, you can probably use your existing networks and interfaces. That means reduced installation and servicing costs. Think ahead here. What will you do when it's time to upgrade or replace your system? Do you want to be stuck with a network consisting of orphan technology? As little as three years ago, "open" was not a realistic option. Today, you can insist on it. And you should.
One strategy many owners are successfully employing is using multiple communications means. For example, they use their facility's LAN as the backbone and access it via wireless and Internet protocols. Wireless doesn't mean just cell-phones and pagers, either. As PDAs become more popular on the production floor, the wireless PDAs have real-time, two-way communication with the PMCS.
Automatic control capabilities. Communication - the remote-monitoring part - is fairly standard among the newer systems that are beyond "entry level." The two major differences between PMCSs are the degree of remote control and automatic control. Many PMCSs are essentially "read-only." You see the information but can't do anything with it. In looking at the systems available, you'll often encounter control capabilities limited to simple setpoints and the control of a few I/O points on a local meter. This is fine for some situations, but you will probably need a more powerful and capable system if you have mission-critical operations.
The most versatile systems offer fully integrated processors for system-wide control of complex tasks, such as generator starting and paralleling, load shedding, and demand control. Because these systems are for mission-critical operations, they include features like hot backup, safe failure modes, and common programming languages.
Many owners initially want just the remote-monitoring capabilities that PMCSs offer. However, as they use the system, they become frustrated that they can't respond with control. They also find they need the control capabilities so they can implement the cost-saving ideas found with PMCS information. Those who've purchased systems that were easily upgradeable to include a control option have been able to make the leap economically. Those who bought systems lacking that upgrade path or modularity have had to choose between the costly route of replacing their existing system or foregoing the control capabilities. What's the bottom line? If you decide on a system without control abilities, ensure the control option is available.
Support and engineering services. All vendors should have a competent staff to assess your needs, make recommendations, and provide technical support. No two situations are alike, and you will need some customization - especially when integrating with existing systems or developing controls. Some vendors do the integration work themselves and provide a single point of responsibility.
Some PMCS vendors can provide ongoing engineering analysis to help ensure you make good use of the information your system collects. Others can provide you with names of third parties to contract out for such services. This kind of support is valuable to organizations that no longer have in-house electrical experts specialized enough to interpret the information, or whose electrical staff simply is too overloaded to deal with it.
Sidebar: Emergency Generator Remote Control
You can get a dedicated wireless monitoring system just for your generators. These systems use the non-voice or "control" channels of cellular systems. Typically, you'll monitor the mechanical aspects of your generator - oil pressure, coolant temperature, fuel level, underspeed - as well as run time and some basic electrical measurements. For mobile generators, you can order a global positioning system locator option.
Such a system, in addition to your PMCS, makes sense if you rely heavily on emergency power generation. It also makes sense if your generators (by nature of their location) are subject to a hostile operating environment, low maintenance, or tampering. You'll need to compare features with the various PMCSs to see if a dedicated system makes sense for your situation.
Sidebar: What to Ask Before Buying
- Can the vendor supply a full range of monitoring abilities you may need, ranging from high-end power-quality instruments to lower cost devices you can install in larger quantities to monitor power by machine, line, or department?
- Can the system use your existing LAN?
- Can you integrate the system directly into power equipment, through compatible trip units, protective relays, UPSs, and similar devices?
- Can the system log, scale, and track parameters other than purely electrical ones?
- Does the system allow you to automate such things as testing and load shedding?
- Will the vendor(s) provide services after commissioning, such as training, upgrades, troubleshooting? If you are using multiple vendors, which vendor is clearly responsible for what service?
- What history of successful systems - similar in size and scope to the one you are considering - can the vendor demonstrate?
- Does the vendor have experience successfully retrofitting PMCS systems into existing electrical distribution systems?