The answer to this question appears at the end of this newsletter.


Replacing Vessel Instrumentation
Vessels (and similar equipment) often contain components that should be replaced or calibrated whenever the vessel is out of service (e.g., for repair). This work is often incidental to the reason for the downtime, and it must be done on a tight schedule because each hour of downtime means lost revenue and possibly lost customers. Complicating matters, work inside a vessel is typically cramped, hot, and dirty.

For example, the mechanics must replace tiles in an annealing furnace, after waiting through five days of downtime for the interior air to cool to 150°F. Standing in a fan-blown breeze, they work in 30-minute shifts. When the project is done, the three-day heat-up process will start.

Your crew has to do more than supply power for fans and lights. Now is the time to replace the dozen process sensors variously located throughout the first and last chambers of the furnace (rather than wait for one to fail three months later). You don't want techs going back and forth for parts and tools, or using up "inside time" to open packaging, strip wires, or tape threads. Nor do you want them crawling in and out to perform the requisite testing.

Different crews working in the area will slow each other down, yet all work must be concurrent with that of the mechanics. You must work "between the work."

To succeed, plan the job. Then do a mockup, and rehearse several times. You don't need to duplicate the actual vessel; you just need to identify the steps and what's needed to perform each one. A mockup can consist of a few tables set up in the parking lot.

Consider having a dedicated support crew (cannot include the vessel attendant) outside the vessel, even if they spend most of their time standing around. Do these practice sessions, and the "low utilization" support crew, seem like excessive uses of labor? Ask your plant manager how much revenue the plant loses every hour that vessel is out of service. The answer may quickly justify any labor cost concerns. But don't throw people at the job; plan the job for fastest execution and staff it accordingly.

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Answer to Electrical Troubleshooting Quiz
Erratic indications of process variables may result from loose connections -- so check screw terminals and crimped connections.

If the problem remains, suspect electromagnetic interference (EMI) or radio frequency interference (RFI). You may be able to capture an RFI event using a recording DMM or power analyzer. Look for any source of RFI -- such as fixed or portable wireless equipment -- especially near the sensor wiring, the I/O rack, or the control console.

A common source of EMI is a voltage induced from 480V or 120V wiring running parallel to the wiring between the sensor and the transmitter (other likely places are around the I/O rack and around the operator station). The transmitter sees the induced voltage in addition to the mV input from the sensor as though they are one big input signal. The resulting 4 mA to 20 mA output signal is artificially large.

If specific equipment switches on (or off), coincident to the appearance of the anomaly, wiring for the equipment is probably your EMI source.

Having trouble finding that EMI source? You may need to lift wires via the "divide and conquer" method. First, determine the timing of the anomalies, so you can plan downtime around when one is likely to occur. Coordinate with the operators to determine how long you'll have.

Identify the affected transmitter, and verify against the loop diagram. Shortly before an anomaly is due to occur, break the loop at the transmitter and place a recording DMM on each side. Suppose you saw no anomaly on one side, but you saw a spike on the other. Now you know the direction in which to continue troubleshooting.

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Show & Events
Visit the 2006 EC&M E-TradeShow, a
Year-Long Virtual Business Event
Don't miss these scheduled seminars on October 18 in the EC&M e-Tradeshow:

• "The Basics of Insulation Resistance Testing," by John Olobri, Dir. Sales and Marketing, AEMC Instruments (9:00 am EST and PST, Conference Room A)
• "Good Project Management, Enhancing the Bottom Line," by John DeDad, Senior Director, Editorial and EC&M Development (11:00 am EST and PST, Conference Room A)
• "Presenting AEMC's 3-Phase PQ Analyzer," by Ed Cunie, Eastern Regional Manager, AEMC Instruments (10:00 am EST and PST, Conference Room A)
• "Electrical Market News Update," by Jim Lucy, Chief Editor, Electrical Wholesaling, and Dale Funk, Chief Editor, Electrical Marketing (10:00 am EST and PST, Conference Room B)

Before attending these events, make sure you visit the 2006 EC&M e-TradeShow, a year-long virtual business event. In addition to attending live activities at conference sessions scheduled throughout the year, you can meet with exhibitors in virtual exhibit halls. You can also access past presentations that are archived in the e-TradeShow. Employing the latest interactive 3D technology, sponsors use online trade-show booths to generate leads on a continuous basis throughout the year, while interacting live with customers and prospects during scheduled events. Free access and all the information you need are available at the event's Web site.


Maryland Facilities Expo
Held October 25-26 at The Fairgrounds in Timonium, Md., the Maryland Facilities Expo is a free two-day trade show, offering an exhibition of products and services along with educational seminars for facilities personnel working in all types of industries, including commercial, industrial, educational, government, health care, hotel and resort, distribution, and warehousing.

A few sessions in the conference track that may be of particular interest to EC&M readers include: "The Top 10 Cited OSHA Standards," presented by Eddie Bell, Chesapeake Region Safety Council and "Standby Power Generators -- What You Need to Know," by Al Grimes, Curtis Engine and Equipment, Inc.

For more information on this show, visit the event's Web site.