Wednesday, November 24, 2010

November Newsletter

Well, it is nearly the end of November.  The day before Thanksgiving, the day after a blizzard warning in which we mostly received wind.  There is currently about 3 or so new inches of fresh snow but the real news is the temperature.
It was 1 degree on the way into the office this morning and quite a fun drive in, as the roads were very slick.

We are currently working on a project that is nothing short of ambitious for us.  We are going to build and market a new product that will be sold exclusively through a Rep company.  We have been in various meetings with factories for items we will need to embark in this venture and still have some more negotiating that needs to be completed prior to an announcement. 
I will let you know as soon as things are all finalized.  Needless to say, we are all a bit excited about this.

The holidays are upon us with things kicking off tomorrow-on Thanksgiving.  It’s always a difficult time to do “business as usual” do to the fact that a number of our factories will be closing for the holidays or for “inventory”.   Every year, we face the same hurdle with our suppliers but somehow manage to pull through. 

So what I’m trying to say is, although we do our best to have as many of the items that we think we may need to fix whatever problem may arise; we may not have the part you need.  This leaves us all at the mercy of the factories.  Hopefully, this season will come and go and most of you will not have the misfortune of being down for any reason.  But if you do happen to go down, rest assured that we will do our very best to help correct the problem if called upon.

Everyone have a great Thanksgiving and enjoy this Holiday Season.


Friday, November 19, 2010

Capacitor Installation Problems

In the past few years, facilities that have capacitors installed for power factor correction have been experiencing quite a few problems with the units failing. Whether it be a few individual cells or the entire bank failing, these problems have started to show up now on a more frequent basis.

I guess if I think back, this has been happening for the past eight or more years but seem to be worse in the last two years than ever before. Most of the failures are on “fixed” bank units. That leads me to a few conclusions about what may be going on at these facilities:

- The load profile has changed either up or down

- A Main Transformer has been changed out

- More Non-Linear load has been added to the system

In any case, something has changed at these facilities that is now causing the capacitors to fail.

Let’s take the Load Profile for example:

When originally installed, the capacitor sizing is based on the kW load of the facility. What also comes into play is the Transformer size, Impedance, existing Power Factor, Site Voltage and other things that we look at such as Linear verses Non-Linear load.

Factoring in all of the above information, we calculate how many kVAR will be needed to correct the power factor. Also the placement of the capacitor bank(s) is looked at very closely. We determine where it will be best suited electrically (depending on system) for survival in the facility. We also make sure that we are not “tuning” the system to a frequency that is close to critical frequencies that are generated by most non-linear loads, such as the 5th, 7th, 11th harmonic.

In most every instance that we have had capacitor failures after a few years of service, I have found that the user has added Variable Frequency Controllers to the system or some other non-linear device(s) that are now causing harmonics that become detrimental to the existing capacitor bank. In one instance, I found that the Main Transformer had been changed out to a different size unit. This caused a rise in voltage that is bad for the power factor and also re-tuned the system close to the 5th harmonic.

In conclusion, what I am trying to say is that if you have power factor capacitors at your facility; pay close attention to changing, adding or deleting anything on the electrical system as this can cause you major headaches in the long run.

If you want more information, you know where to get it.