Manufacturing Process Unexpectedly Halted

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This medium-sized manufacturing facility, located in an industrial park that experienced an unexplained shutdown of several adjustable speed drives (ASDs) , wreaking havoc on key process equipment. Each day, at approximately 6 am, the utility-owned PF capacitor kicks on to improve the voltage of inductive loads prevalent in many of the park’s manufacturing facilities. The ASDs are conditioned to anticipate this expected power quality event and are typically able to ride through the problem. So when one of the ASDs closed down and interrupted the continuous stream manufacturing process, the facility manager needed to learn why, correct the problem, and prevent it from happening again.

As you can see from the attached screen capture, a second, unanticipated capacitor switching event occurred shortly after the first. This event was categorized by the Encore Series System Capacitor Switching Answer Module , enabling the facility manager to pinpoint the exact source of the problem. Further analysis showed that the ASD shutdown was the result of an overcurrent trip, which was quickly remedied preventing hours of downtime, at a loss of $10,000/hour.

Harmonics Generated from the Source

The subject company manufactures meat products such as sausage, salami, and bologna. Most of their load consists of HVAC and refrigeration as they have about 6000 sq. ft. of cold room storage. They also have machinery such as grinders, slicers, and presses. The facility is served by a 120/240V through a utility-owned 500 kVA High-Leg Delta transformer that they share with another factory.

Interruptions occurred when a main 1200 amp circuit breaker was tripped frequently. The events occurred often and sometimes several times a day. Previous measurements had not shown the reason for the events as the highest measurement of current shown was 760 amps, which was not enough to cause the breaker to trip.

From the recordings, the following was noted:

• At times the peak current exceeded the 1200A breaker rating without tripping the breaker. An interruption that was tied to such a peak current was detected only once during the measurement period. Further investigation from the wave forms captured determined that the voltages were distorted during such times. This distortion caused nuisance tripping of other breakers and caused the capacitor banks to fry.
• A long-term measurement showed that the capacity of the breaker could be reached when a combination of tasks occurred at the same time.
•  Since most of the load at this site is linear, no harmonics are generated from within the facility. When we looked outside the factory, the cause of the distortion was traced to a faulty power transformer.

Dranetz App Note: Corrugated and Cardboard Packaging

We’ll bet you don’t spend a lot of time thinking about corrugated and cardboard packaging, do you?

But take a close look and you’ll see that it’s all around us.  According to the New York Department of Environmental  Conservation (NYDEC), 90% of all products shipped in the United States are shipped in corrugated and cardboard boxes. That’s a lot of boxes, trees, pulp, power, and energy.  And that’s where Dranetz comes in.

Recently, Dranetz was asked by a large corrugated packaging manufacturer with multiple manufacturing sites on the East Coast and central parts of the United States to assist with assessment of planned expansions as well as ongoing energy management, and provide proactive power quality analysis. Using both the PowerVisa power quality demand & energy analyzer and a permanently installed Encore Series power monitoring system, the electrical design team was provided with crucial information on a host of issues, including energy usage and PQ problems originating all the way back to the electric utility itself.

The initial results were so successful, that over the next year an Encore system has been budgeted for every one of their plants. To find out more, click on the link below to download the complete Dranetz application note.
Corrugated and Cardboard Manufacturing Application Note

To find more information and application notes about power quality and energy management, please visit us at www.dranetz.com.