Wednesday, March 25, 2009
This is where the power of LED's comes into play. Sure it's more energy efficient, but it's in the ability to control the angle and direction of each LED in the array of an LED fixture that gives the major benefit. Why so? By controlling the angle, the variation of foot candles can be much lower overall than traditional methods and you can then base the lighting levels based on minimums instead the average. With LED site lighting you will get less shadowing, trespass, conserve light, and probably use less fixtures. The color rendering is better as well which is great for security.
The major players that seem to be emerging are Beta, GE, and Kim. Be on the lookout over the next 3 to 4 years in the industrial electrical products market to see more breakthroughs in LED site lighting!
Friday, March 20, 2009
First, Maxlite has a high lumen CFL (compact fluorescent) for use as a field replacement for metal halide lamps all the way up to 400w (yes, 400w!). How it works is you replace the 175, 250, or 400w HID lamp with the high lumen CFL. The CFL typically seems to run about half the watts as the HID lamp. You bypass the HID ballast inside the ballast housing and, BAM, you have cut your watts in half without replacing the fixture. Seems to good to be true huh? It seems very intriguing but there are a few things to consider. First, the lamp life is rated around 10,000 hrs. This is pretty low compared to HID or the other option of replacing the entire fixture with 46,000hr T8's. Also the temperature rating is around 100 or 120 deg F which will be an issue in some areas and applications. They did a very nice design with an integral heatsink and cooling fan, but be sure to consider the worst case temperature when looking at this. I think this could be a viable option for some circumstances, just be sure to look at all the application angles. T8 and T5 linear high bays or even 320w metal halide with pulse start will probably be a better choice for most applications, but this could be a fit for some.
They also have some other neat products, LED PAR replacements, LED light bars and my favorite...... a 2x4 LED lay-in fixture. This is the first LED 2x4 I have personally seen that works. It is not a bunch of LED's formed to fit in T8 lamp sockets like some others have tried, it is an actual flat array of LED's. Also, the profile is very, very slim, which is great for retrofit applications. The light output seemed adequate and the color seemed fine too. The price is up there for the 2x4 and also the 2x2 (yes, they have a 2x2). They are probably selling in the field for around $600 for a 2x4. I'm not sure how many will be sold at that price, but it is an interesting option for those that are hooked on LED's. Be sure to check them out or call your local lighting distributor for info. Maxlite.com
Thursday, March 12, 2009
In the past, Thermal imagers have cost between $6,000 and $20,000. The Ideal unit, #61-844 lists for $3,500. Thermal digital cameras have been used in the industrial and maintenance segment for years. See below for some common uses.
- Troubleshoot hot spots for switchgear, panelboards and breakers. Heat images overlapped on a digital image can show weak connections and hot spot on "legs" of equipment. This gives a great head start on doing PM (preventive maintenance).
- You can also use these for checking motors, motor bearings, gearboxes and other PT (power transmission) equipment. It helps to get a baseline picture of mechanical equipment while it is working fine to be able to go back and compare later.
- Process ovens, boilers, cooling boxes can sometimes have leaks or process heating/cooling that causes them to be inefficient. Thermal imagers can be used to check the process and equipment.
- Outside of the industrial electrical market, Thermal imaging cameras can be used to help find leaky windows and heat/air loss for buildings or homes.
The Ideal thermal camera is priced more affordably than other's so it should do well with maintenance departments and in-house electrical personnel. A few drawbacks to the camera are, it only has manual focus and it's optimum resolution is only good to about 20'. Other than that, it's packs a lot of functionality for a small price.
For more information on the Ideal Thermal Imager call your local distributor or visit idealindustries.com
Monday, March 9, 2009
When using an AC motor with a variable frequency drive, you actually have a few things to keep in mind. Just because the motor is namplated as "Inverter Duty" or "Inverter Rated" doesn't mean it will fit your application. These terms are used on motor nameplates and in catalogs with a very loose meaning. The only real industry standard is Nema MG1 part 31. It addresses voltage insulation issues.
- Voltage issues and Nema MG1 part 31. It states that a motor can withstand voltage peaks of 3.1 times the motors rated contiguous voltage, usually 600v ac, with a rise time of .1 microsecond or more. Basically, in English, this means the motor can withstand the pulse spikes created by the drive up to 1800 volts. If the motor can't handle these the windings can fail and short and voila! you have a dead motor. Ask the motor manufacturer what the inverter rating is on the windings. Many have motors that are good to 1800 volts. Some even offer 2000 volt insulation. (motor lead length is also an issue here to be covered in a later bullet)
- Thermal issues. This issue is not very well regulated and your on your own. Not only can voltage spikes kill a motor, but heat does too. Motors are rated at a base rpm (1200, 1800, 3600 etc). The fan on a TEFC (totally enclosed fan cooled) motor is designed to give optimum cooling at that speed. When you start to slow the motor down, the fan slows down and the motor can get hot. Find out what the turndown ration will be for the application. This means if you are going to use the drive to run a 1800 rpm motor at 900 rpm this is a 2:1 ratio. Make sure your motor is rated for the application's turndown! Otherwise you cook the motor, bearings and insulation and viola! you have a dead motor. Motor manufacturer's usually have different motors to address turndown ratios needed. Ratios from 4:1 all the way to infinite:1 (rated to run at zero rpm continuous) are not uncommon. Motor manufacturers can do this by oversizing the frame, adding a constant speed blower to the motor or even by increasing the iron content in the frame to help dissipate heat.
- When looking at what motor to use with your AC drive, also factor in "how far away will the motor be from the AC drive?" The higher the voltage, the more important this is. For 460 and 575 electrical systems this is crucial. When you have long leads to the motor you can build up dvdt spikes and the spikes can exceed the voltage rating on the motor. Be sure to consult both the AC drive manufacturer and motor manufacturer for the recommended maximum lead length. In some cases, it will be necessary to use a load reactor or filter to clean these spikes up to avoid a viola! dead motor and downtime in the plant. I've seen everything from 50 feet maximum to others publishing 1000' with their drive and motor. Most drives have made improvements on cleaning up the dvdt spikes but always ask about this!
This post won't make you an expert, but hopefully it will give you some ammo to make a better decision next time you're looking for an AC motor and AC drive combo.
Saturday, March 7, 2009
Before shopping around here's what you need to know for basics:
- Input Voltage
- FLA (Full Load Amps) on the motor nameplate or spec. AC Drives are actually sized by amps/current not HP (horsepower). Although most consumers rarely size by current, it's the safest method. If you compare similar drive brands by HP and look at the continuous current rating you'll be vastly surprised. Some brands exceed the NEMA FLA for the HP it is rated for (FYI this extra current can bail you out on a tough load). Some brands cut it close. Others have introduced a smoke and mirrors approach with terms like Heavy Duty, Light Duty. Proceed with caution in selection on brands using this terminology.
- Application-What are you using this for? Is it a conveyor? Is it a fan? Maybe a pump (if it's a pump, know which design type it is, *NOTE* be careful with positive displacement pumps!*)
- How do you want to control it? Are you just going to use the keypad for starting and stopping? You might want to use remote control via push buttons for starting stopping etc. Also, do you want to give the variable speed drive (AC Drive) a variable speed reference signal from a speed potentiometer or set it using the keypad, or send a 4-20ma signal from a transmitter? If using the keypad, are you going to mount it on the front of the enclosure?
- What type of environment is it going to be in? If you're not mounting it yourself in a control cabinet do you need to be able to connect conduit (some drives are rated IP20 for their enclosure which is sort of finger safe but you don't have a landing area for conduit)? Do you know the Nema rating of where the AC drive will be mounted?
- Do you need any form of communications for the AC Drive? Ethernet, Modbus, Devicenet, Profibus etc.
- Do you have any breaking requirements? Is it a stopping brake, holding brake, emergency stop application?
- Lastly, this isn't a dealbreaker but ask about tech support via phone or locally. Good tech support is a great intangible often overlooked. Sure, you need to take the time to read the manual, properly wire the drive to the AC motor and attempt to get it running. However, sometimes you may need a little help.
There are a lot of brands out there. Here are quite a few in no particular order (and just because they are listed does not mean I endorse them, be sure to do research on any you are looking at). AC Tech, ABB, Baldor, Cutler Hammer, Emerson/Control Techniques, Danfoss, Fuji, GE, Hitachi, LG, Mitsubishi, Rockwell/AllenBradley, SqD/Tele, Vacon, Yaskawa.