http://www.lmpforum.com/inforum/index.php?automodule=blog Community Blog List Syndication Sun, 30 Sep 2007 00:52:49 +0100 forum@lmpforum.com (LMPForum) IP.Blog 60
In order to reduce energy consumption, there must first be energy wasted, and second, a means of reducing that energy wastage.
You can only save a portion of the energy that is being wasted.

If you are serious about saving energy, you must:

1. Establish where energy is being wasted.
2. Determine how much energy is being wasted
3. Determine possible means of reducing the wastage
4. Determine the amount of reduced wastage
5. Determine the cost and viability of reducing the wastage

Energy wastage generally occurs due to either reduced operating efficiency, or excessive output.
For example, an office is provided with lighting sufficient to light the work areas at night. As the ambient light level is increased, (day time) the supplemental lighting levels required, are reduced, but so often, the full light output is used irrespective of the ambient light levels. The artificial light levels can be reduced, or in some cases totally removed without greatly affecting the light levels at the work area.

It is important that in reducing the energy consumed, you do not reduce the "work" output to a level that it begins to impact on the productivity of the plant. Lighting can often be reduced during the day, pumps and fans can be slowed down when there is reduced flow required.

Energy saving is more commonly related to process control, than to "magic" add on boxes.

Typical add ons for saving energy:

Nola type energy savers for induction motors. - These will save energy if the motor is operating at very light load and is operating inefficiently. Larger and more modern motors are far more efficient than old small motors. There are some applications for saving energy using this technology, but they are very limited.
Motors must be small, operate under very light load for very long periods of time.

Power factor correction. - Power factor correction is a means of reducing the current drawn by an inductive load. This will reduce the line losses in a transmission system, but will have little or no impact on the KWHr meter except where the mater is installed many KM from the connected load and the correction is applied at the connected load.
In the industrial installations, there are usually electricity tarriffs based on KWHrs plus an additional surcharge for poor power factor, or a KVA maximum demand penalty or similar. Money can be saved by a reduction in the penalty, not the reduction in KWHrs.
In the domestic installation, the power is charged for KWHrs used. There is no power factor penalty or KVA maximum demand penalty. There is no financial gain from the addition of power factor correction in the domestic environment.

Lighting Controllers. - Lighting controllers that reduce the level of artificial light during periods of high ambient lighting, will achieve appreciable energy savings. Some controllers permanently reduce the voltage to the lamps, reducing the light output under all conditions. These will reduce the energy saved, but will also reduce the usefulness of the lighting when it is required most.

Variable Speed Controllers. - VSDs can be used to control the speed of a machine. There can be significant energy reduction if the machine is slowed down when it does not need to operate at full speed. For example, pumps operated so that they run at a speed dependent on the flow requirements will reduce the cavitation losses in the pump. If the pump is required to run at constant full speed, the addition of a VSD will actually waste another 5% of energy.]]> Sun, 09 Sep 2007 01:58:16 +0100
At the motor terminals there are capacitors connected across the phases and an adjustable 3 phase load bank.

The motor starter is a softstart with an isolation contactor on the field side (opened when the e/stop is activated). There is also a 3 phase contactor between the motor terminal and the capacitor bank.

The procedure tried so far; start the motor in reverse (remember forward operation is a pump) against a partially open valve (to provide some load), once running at full speed close the contactor to the capacitors, 10-20 seconds later hit the e/stop to disconnect the mains supply. At this point the motor speed dropped away but the outlet valve was opened to increase the speed.

Here's the problem - there was an insulation breakdown on the capacitor feed cables that resulted in a flash-over and futher damage to the cables before the contactor was opened.

Was this due to the reactance of the capacitors and the reactance of the motor combining to create a resonant circuit or just a faulty cable? How do I avoid this in future? How long should the capacitance stay in the circuit once excitation has been achieved and the induction motor is generating?

Further info - motor 250kW, 3phase, 50 hz, 400V - capacitor bank 120kVA per phase - test load 0-400kW]]> Tue, 28 Aug 2007 07:09:23 +0100
The origin of the word is unclear, with some suggestion that it cam from a Monty Pythons sketch.

I can get upwards of 400 SPAM emails a day and it can be an issue trolling through all that garbage. - I don't and I know that I do miss some legitimate emails because of the filtering that I use, but that is life I am afraid.
There is nothing worse than being away and out of contact with the internet for a week or so and finding over 2700 emails waiting to be processed! It would take for ever to open each one and discard the bad and keep the good. It takes long enough just to process the obviously good emails.

The moment that you have a domain name and a web presence, you seem to be a target. There are lots of emails to ficticious addresses at your domain. One of the first steps to take is to not use any of the obvious addresses such as info@.. or editor@.. or webmaster@... etc. These will all be targets. Better that you just filter these addresses and send them to a spam processor or reporting agent.

How can you avoid spam?? you cant. You can however take steps to minimise the volume of spam that you get and there are tools to help you from being exposed to the full volume of spam.

Rule 1. Never publish your email address in any webpage. The spiders are capable of finding email addresses in any web documents including PDF documents. It was possible to fool the spiders by embedding your address in javascript, not any more. If you wish people to be able to see your address on your web page, make a graphic with your address in it. There are plenty of graphics programs that you can use. You can write it out in full in a fasion that a human needs to interpret it and put it together, but be careful, these script kiddies are on to that and can recreate the address from your text if you make it easy for them.

Rule 2. Never use your primary email address in entry forms for unknown or untrusted web sites. Some of these companies are unscrupulous and sell their contact lists on to the SPAM organisations for big money.

Rule 3. Never use your primary email address in magazine articles that you may write. Those pages are often published on the internet as a PDF file and your address can be spidered from there. If at all possible, create a secure web based contact page that will send comments and messages on to you.

Rule 4. If you have your own domain name, you can create as many email addresses as you like. Use a new address for each new company you deal with and record who has access to what address. Better still, make it obvious that you are doing this by making their name part of your address. You can then easily identify where any address leaks are occurring. If you suddenly start getting SPAM to an address that you gave to company XYZ, then you know that they have a contact list leak, or are onselling addresses. Either way, you probably don't want to hear from them again, just send them a message expressing your disapointment in their behaviour and filter that address straight into the junk box.

Many of todays ISPs offer a level of SPAM filtering to reduce the rubbish that you get in your INBOX. This can be great and some of the filters work really well. Be careful with the challenge type filters that were very popular. These can result in even more traffic as the bounced emails get sent between spoofed and nonexistant addresses.

There are also SPAM filtering specialist sites such as http://www.spamcop.net who provide a spam reporting service and also a spam filtering service. You can route your email from your Inbox through these filtering services to reduce the spam considerably.

SPAM reporting services such as SPAMCOP and Bluesecurity analise any SPAM reported to them and operate to identify the originators and close them down. It is worth reporting spam via these organisations, but be careful, there are some who are really using an apparent front as a means of gaining even more addresses.

SPAM filtering programs that operate on your PC either as a filter plugin for your email program, or as a prefilter such as Mailwasher are also well worth looking at. The latest version of Mailwasher include the ability to report the spam to reporting services.

Once your email address is in the spam system, it is sold to many and you can not get it out again. You can change addresses frequently or use filtering techniques to keep the volume down. The best thing to do is to try to slow down the publication of your address by following the rules above and using common sense. It is not a case of if your address becomes a target, but when.]]> Wed, 03 May 2006 23:39:14 +0100