Forum Replies Created
Well, I don’t think electricity is in any danger of disappearing any time soon. The fuel sources (required to make the electricity) are likely to change a few times over the next century or two.
LED’s are most likely to be the future for all lighting soon enough. The only thing holding them back now is price and assembly costs. But that will be better once the automation is put to work.
I must say, I’m not sure what kind of lighting you mean by “GLS” or “FTL”. Not all of us use these terms as often as you might because you are in a particular segment of business. If by FTL you are referring to “fluorescent tube linear” your numbers may be too general to make a valid comparison. Perhaps you have been talking to the marketing folks a little too much.
Lighting has frequently been too complex of a subject for many people to understand. By that I mean that terms such as CRI (color rendering index) really does not compute for most people. But it can be extremely important in some situations. Other terms have been generated due to technical issues with respect to getting the best response for your device (or lamp) and most people really don’t care. In fact, if it turns ON then that is generally all they want to know. If it doesn’t look like enough light, they get a bigger bulb. That is about all that most people (>90%) really care about. As to how much it will save, … there is always tomorrow to pay for it. It just needs to work when it is turned on!
From the information you have given, you are obviously talking about an industrial type of device. Consequently you will need to consider other things such as an automatic cross over switch and other items.
The units of measure will generally be in KVA. Note that the K means “thousands”, the V stands for voltage which you have specified, and the A stands for current in Amps. If you already know what devices must have power, they will likely be part or all of a substation near your switch gear (breakers, etc.). Frequently you can observe the typical current being used at that point. Understand, however, that many of the devices, lights, and more, may not be in use at the time of your observation.
In order to leave a little room for the unexpected, you need to consider the maximum current needed at any point right now, add 10% for future growth and make sure that figure does not exceed 80% of your generator. If you run above 80% of the full load power, you will generally wear out the generator before it should be. Remember that some loads require a momentary higher than normal current to start up. That has to come from somewhere!
That does sound rather confusing. Generally a “built in diode” is referring to a EMF kickback suppression device. When the power to a coil in a contactor is removed, the residual magnetic field collapses very rapidly producing a potentially destructive voltage to your solid state control device. Generally the diode will also have a resistor connected to it to protect the diode should someone connect it improperly. Without the resistor, the diode will be destroyed when connected improperly.
The resistor also increases the risk of damage to the solid state control device. That being said, a diode in the output leg of the control device may also add to the protection until its ratings are exceeded.
Getting back to the language issue, the term “Auxilliary Contactor” may be a reference to a general purpose contactor that is not intended to be used as a “Safety Device”. Or it may be talking about a secondary contactor used to disrupt a circuit should the primary device fail to open. Welded contacts are a real concern when products are not matched to the application appropriately. And sometimes, when certain products have reached the end of life, they may not fail in a desirable way. That is why there are frequently other ways to disconnect power from a device.2012/03/01 at 5:32 pm in reply to: Electric VS Electronic Earthing For PLC RACK/Chasis #12820
I’m not sure I understand your question. I assume that by electrical earthing you are referring to your AC power source ground or earthing. This is a fundamental part of your power distribution and should always be available to your equipment. For electronic earthing, I assume you are talking about the input and output sections of the PLC. If you are using AC modules, then your neutral should be very close to the earth potential. You may, however, be able to measure a small voltage (less than 5VAC) between neutral and earth/ground depending on several factors.
If your I/O modules use DC power, then you may not want to use any earthing connection because your DC power is usually generated from AC power. A connection to earth/ground on both sides of that power supply may cause a partial short circuit inside the power supply. Most of the newer power supplies now have complete isolation but any noise from the AC side can infiltrate the DC side and cause problems.
Mixing AC and DC successfully takes some specific electrical knowledge and then verification if you attempt it.
There is, in fact, such a device and it is used in a lot of battery operated products like cell phones, portable computers, and more. The device is a DC-DC converter that takes power in at a steadily decreasing rate while it provides a reliable and steady output voltage. This is necessary to keep the electronics operating in a predictable way. Without it, the circuitry would become unstable and a characteristic failure mode would become apparent.
Another way to determine the load schedule is to go to each circuit breaker panel and count the total amps the panel could deliver. Add up the total number of amps that panel could provide and multiply by the voltage it provides.
That would provide the peak load schedule. A more realistic picture could be obtained by measuring the current for each breaker while everything is in use. You will need a current clamp to get that. Some circuits will be switching on and off while you are measuring so take the highest reading you see for each circuit. That would provide your actual usage load schedule. Make sure to record which breaker number and the reading together for each panel.
This device is a special relay that will signal or disconnect a more expensive circuit if it detects a problem with the voltage feed. Some of them will monitor three phase voltage for dips or overshoot (variations greater than 10% of nominal typically). It may also monitor loss of a phase or phase reversal. It is a level of protection above that of a fuse or circuit breaker.