Five ways to ensure better power quality

Unscheduled equipment downtime can result in delayed shipment and lost sales for the business, and loss of sleep and credibility for the plant operations manager.

09/21/2011


Courtesy: Power Standards LabIn today’s manufacturing environment, unscheduled equipment downtime can be very costly to a plant operator, resulting in delayed shipment and lost sales for the business, and loss of sleep and credibility for the plant operations manager. While there could be countless reasons for productions lines grinding to a halt (worn components, software failure, natural disaster, and so on), bad power factor is one of the most common, persistent, and difficult-to-diagnose reasons. Not only can a voltage sag or spike wreak havoc on a plant’s production schedule, it can burn or damage expensive equipment and pose safety concerns as well. The cost of damaged equipment can equal and even exceed that of lost production.

One common reason for not dealing with a power problem is that facilities managers often feel that they do not have control over the power their utility provides, or enough knowledge to discuss it. This doesn’t have to be the case. Below are five ways a facilities engineer can get on even ground with the utility and ensure that power problems at least won’t keep their plant idle.

1. Monitor power quality all the time.

A power glitch causes your production to halt. You call your utility to complain. The utility sends over an engineer who hooks up a monitor to the main panel, leaves, then comes back a week later to read it. Nothing unusual has happened that week—your utility is off the hook, and the problem is back on you.

Sound familiar?

Embedding a permanent power quality monitor inside your panel keeps you in the know about your power, day in and day out. It is the single most important step you as a facilities manager can take to ensure you are not working in the dark.

Whether the problem originates inside your facility or out, the least you can do is to know.

2. Find out if the power quality problems you are experiencing are caused inside or outside your facility.

Typically, a voltage sag passed down by the utility (upstream voltage sag) will cause your current to drop. On the other hand, a surge in current accompanied by a voltage drop is a pretty good indicator that the voltage drop happened inside your facility (a downstream voltage sag).

You can use these general rules—and visual information like that in the graphs below—to determine where to start your troubleshooting process.

3. Have a record.

A picture is worth a thousand words, and when you are trying to prove a point to your utility, it’s priceless. A record of trends or a graph of a captured event (RMS or waveform) will help you discuss specifics, rather than general complaints, with your utility and help you resolve your problem faster.

4. Keep tabs on voltage trends.

To ensure “good power,” you really need to know what “good” means for your equipment. Keep tabs on the voltage you receive, and make sure it falls within your equipment’s standard operating parameters.  If it doesn’t, you may want to bring up the issue with your utility.

If the power you receive is within the expected parameters and you keep having equipment failures, testing your equipment is a good idea.  For more on testing, read Voltage Sag Testing for Commercial and Industrial Equipment, by Andreas Eberhard, Power Standards Lab.

5. Know what’s going on behind your UPS.

It is common practice to deal with pesky upstream voltage sags by installing a UPS. While this does save equipment inside the plant from getting burned or a process from being interrupted, it often obscures ongoing problems that are best resolved.

UPSs wear out faster when they are hit with bad power on a regular basis. If a UPS goes down earlier than expected, you are not only left unprotected but blind to what hit you. 

Monitoring both before and after the UPS will tell you:

  • What exactly your UPS is protecting you from, and
  • Whether your UPS is working the way you expect it to.

This information allows you to fortify your UPS backups if necessary, improving your power environment overall.

Dimusheva is a technical writer at Power Standards Lab. She can be reached at ani(at)powerstandards.com.



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