Terms AC1 and AC3

AC-1 - This category applies to all AC loads where the power factor is more than 0.95. These are primarily non-inductive or slightly inductive loads, such as heating. Breaking the arc remains easy with minimal arcing and contact wear.

 

AC-3 - This category applies to squirrel cage motors with breaking during normal running of the motor.

On closing, the contactor makes the inrush current, which is about 5 to 7 times the rated full load current of the motor.

On opening, the contactor breaks the rated full load current of the motor.

Advantages of LED light bulbs

How far the light bulb has come. For years incandescent bulbs were the only game in town. But in more recent times consumers have seen new choices come along, such as compact fluorescent light bulbs (CFLs) and light-emitting diodes (LEDs). Sometimes people prefer a certain type of light bulb for the impact they hope it will have on the environment, and other times people choose bulbs based purely on the kind of light they cast. LEDs compare favorably versus incandescent bulbs in some areas. They produce their light from the movement of electrons across a semi-conductive material, while incandescent bulbs have a filament that glows when heated by an electric current. LEDs are said to last as long as transistors -- that's much longer than incandescent bulbs. LEDs have a typical life span of about 30,000 hours, as opposed to the 750 hours that a traditional incandescent bulb will last.

 

Furthermore, an LED's plastic construction is much more durable than glass bulbs. Their small size enables them to be used in more applications, such as in electronic circuits. However, the biggest advantage of LEDs boast over incandescent bulbs is their greater efficiency. LEDs produce light without heat, saving all of the energy that goes into heating filaments for incandescent bulbs. A 2007 study by the Alliance to Save Energy determined that if half of all incandescent decorative Christmas bulbs were replaced with LED bulbs, for example, this could save the U.S. some $17 billion dollars a year in energy costs.

 

So the LED bulb uses much less electricity and causes much less waste than do their traditional incandescent light bulb counterparts, producing much less carbon dioxide. As with most things, however, there is an unfortunate downside and that's immediate cost. LEDs cost much more per bulb than incandescent bulbs, and regardless of the long-term savings they might offer, it's hard for people (especially during difficult economic times) to put so much of their monthly cash flow into expensive light bulbs. Time, and lower prices, may change that equation, however.

 

Source : How stuff works

Industrial Control Wiring Guide

DOWNLOAD :

http://www.modon.gov.sa/en/mediacenter/InformationCenter/Books/Industrial%20Control%20Wiring%20Guide.pdf

 

International Power Plugs & Sockets

KW to Ampere calculation

DC kilowatts to amps calculation

The current I in amps (A) is equal to 1000 times the power P in kilowatts (kW), divided by the voltage V in volts (V):

I(A) = 1000 × P(kW) / V(V)


 AC single phase kilowatts to amps calculation

The phase current I in amps (A) is equal to 1000 times the power P in kilowatts (kW), divided by the power factor PF times the RMS voltage V in volts (V):

I(A) = 1000 × P(kW) / (PF × V(V) )


 AC three phase kilowatts to amps calculation
 
 Calculation with line to line voltage
 

The phase current I in amps (A) is equal to 1000 times the power P in kilowatts (kW), divided by square root of 3 times the power factor FP times the line to line RMS voltage VL-L in volts (V):

I(A) = 1000 × P(kW) / (√3 × PF × VL-L(V) )


 Calculation with line to neutral voltage
 

The phase current I in amps (A) is equal to 1000 times the power P in kilowatts (kW), divided by 3 times the power factor FP times the line to neutral RMS voltage VL-N in volts (V):

I(A) = 1000 × P(kW) / (3 × PF × VL-N(V) )

Understanding Type 2 Coordinated Protection in Motor Branch Circuits

The new IEC (International Electrotechnical Commission) standard, publication

947 “Low Voltage Switchgear and Control, Part 4-1: Contactors and Motor Starters,”

has been recognized by UL (Underwriters Laboratories) and is becoming

widely accepted by designers and users of motor control in the U.S. This standard

addresses coordination between the branch circuit protective device and the motor

starter. It also provides a method to measure performance of these devices if a short

circuit occurs. This standard defines two levels of component protection in the

event of a short circuit: Type 1 and Type 2 coordination.

 

This Product Data Bulletin describes:

 

_ How to conformto the new standard using motor controls built to meet

NEMA and IEC standards

_ Related benefits associated with Type 2 coordination

The IEC standard for motor starters and contactors, 947-4-1, defines two levels of

protection/coordination for the motor starter (contactor and overload relay) under

short circuit conditions. Each level of protection is achieved by using a specific

combination of motor starter and short circuit protective device.

_ Type 1 Coordination

Under short circuit conditions, the contactor or starter shall cause no danger

to persons or installation and may not be suitable for further service

without repair and replacement of parts.

_ Type 2 Coordination

Under short circuit conditions, the contactor or starter shall cause no danger

to persons or installation and shall be suitable for further use. The risk

of contact welding is recognized, in which case the manufacturer shall indicate

the measures to be taken in regards to equipment maintenance.

Faults in electrical systems are most likely to be of a low level, which are handled

well by motor controllers built to meet Type 1 coordination standards. After the

fault is cleared, the only action necessary is to reset the circuit breaker or replace

the fuses. In situations where available fault currents are high and any period of

maintenance downtime is crucial, a higher degree of coordinated protection may

be desirable.

Many industries are dependent upon the continuous operation of a critical manufacturing

process. In these conditions, it is especially important to understand that

Type 1 protection may not prevent damage to the motor starter components. In order

to ensure that high level fault or short circuit does not interrupt a critical process,

it may be prudent to consider implementation of Type 2 coordination in the

selection and application of low voltage motor controllers.

Type 2 coordination, which has no equivalent U.S. standard, does not permit damage

to the starter beyond light contactwelding, easily separated by a screwdriver or several

coil operations. Type 2 coordination does not allowreplacement of parts (except fus-

es) and requires that all parts remain in service. Beyond providing basic electrical and

fire protection, it also minimizes lost production, reduced productivity and unscheduled

disruptions resulting fromdowntime needed to replace or repair a starter.

 

SQUARE D Product Data Bulletin

Why Are Copper Bus Bars Plated?

Even though copper is the most popular choice for use in bus bars, and used very often in other electrical applications because it is more resistant to rust and corrosion than other metals, this doesn’t mean that it won’t oxidize over time.

 

When metals oxidize, the resistance in the conductive metal will increase, requiring more power to be used to carry current along the surface. When the copper oxidizes beyond a certain point, the metal can begin to flake and fall apart.

 

Many metals are plated in order to help them retain their positive qualities and attributes. When it comes to copper bus bars, plating is an important factor in longevity as well as maintaining the integrity of the conductive surface. When copper bus bars are not plated, over time the surface will oxidize. When that occurs, then more power is required to push electricity along the surface because the oxidized surface simply doesn’t conduct as well as a smooth, plated surface.

 

Plating, using tin or silver acts as a coating over the surface of the copper, helps to protect the copper from oxidizing. While this will not completely prevent oxidizing over a long period of time, it will dramatically reduce the effects of such oxidization. The reason why tin and silver is commonly used in the plating technique for copper is that both metals are considered soft metals, easier to work with when plating, and more importantly they don’t offer a great deal of resistance to electrical conductivity.

 

Which is better? Tin or Silver?

 

Throughout the industry there are different thoughts about which metal is better for plating copper, tin or silver. 10 microns of tin will outperform 1 micron of silver. With the price of silver climbing, tin becomes more economical, even though ten times the amount of tin will be required to do the same job.

 

When using silver to plate copper bus bars, a minimum of 3 microns should be used, and preferable 6 microns. On top of that, an anti-tarnish would need to be applied as well to protect the finish. In most fixed bus bar applications, tin is recommended. Silver should be used for moving bus bar parts in which arcing may be a concern.

 

For both tin and silver plating, anti-tarnish is important to keep the surface clean and conductive. When working with copper bus bars, plating is essential not only for longevity, but also integrity and safety.

 

Copyright :

http://blog.prv-engineering.co.uk/2012/05/why-are-copper-bus-bars-plated/