Electrical Engineering

There is no resistance between cathode and anode when measured with a multimeter. You can also lick the terminals. If charged, it'll taste much like the terminals of a 9v battery, which, interestingly, tastes much like going down on a girl.

A loss of excitation will cause the generator to start drawing more and more reactive power over time. Over the first few seconds, and until about thirty seconds after the LOE (depending on the load on the generator before the loss of excitation occurred), active power will stay relatively constant, but reactive power will continue to be absorbed from the rest of the system, and voltage levels will drop. Eventually, the magnetic field between the stator and rotor degrades too much, pole slipping and loss of synchronism will occur. At this point, catastrophic damage will likely have been done to the generator.

An open-circuit test measures a transformer's iron losses. With no current flowing in the secondary windings, and only a tiny 'magnetising' current flowing in the primary windings, there is no significant energy lost due to the resistance of the winding conductors. So a wattmeter attached to the primary of the transformer will not read any 'copper losses', only the 'iron losses' that occur in the core.

To reduce slope overload distortion ,the step size must be increased when the slope of the input signal is high.

The sawtooth is better able to

match the message in the regions of steep slope.

A simple example, and it basically relates to buildings, is in Christmas lights strewn on the Christmas tree. If your Christmas lights are in series, if one bulb becomes duff, all the other bulbs also go out. So which bulb is duff (dead)? By testing each bulb you will eventually find the duff bulb and replace it.
If the Christmas lights had been parallel, one duff bulb would not affect the other bulbs. It would be very apparent that the only dud bulb (not lit) in the parallel circuit needed to be replaced.

So you don't try to put in more current than they can handle - so they don't catch fire.

These relay sense the Negative Sequence Voltage components of system supply & offers protection against Phase Failure, Phase Sequence Reversal with Under/Over Voltage conditions which are dangerous to motor winding and cause motor burnouts.

A normally open contact is similar to a spring loaded switch, found in push buttons, and relays.

For a push button, when you push the button, the button head has a piece of metal that makes contact between two external screws, where the wires are attached.

For a relay, the concept is the same, but instead of pushing the button yourself, the relay would be turned on and off by an external electronic device.

Electrical energy will always create heat because there will always be some component of resistance in any circuit - though it is often considered as negligable.

Electrons "bump into" atom nuclei in the conductive material, transferring some amount of kinetic energy to them. Temperature is fundamentally a measure of atomic kinetic energy. So as a material's resistance increases, for a set current, the amount of "bumps" increase and so the material will get hotter.

In theory; any material can conduct electricity given enough voltage, but materials which we refer to as insulators would need an extremely high voltage and would be destroyed after conducting only a short burst of current.

I hope this answers your question.

CLEANING

Cleaning was one of the earliest industrial applications of ultrasonics. Objects to be cleaned are placed in a bath of fluid which is violently agitated by a number of ultrasonic transducers. The fluid may be water or solvent based, depending on the application. Traditionally the transducers were fitted around the walls of the cleaning bath, but some modern equipment uses an external transducer attached to a resonant probe which transmits the vibrations to the fluid.

The ultrasonics may affect the cleaning process in several ways. Rapid movement in the fluid can help to de-wet surfaces, overcoming surface tension, and may also help to dislodge dirt particles and carry them away from the surface. Cavitation is probably the most interesting (and potent) effect - the shock waves generated by tiny implosions of vapour bubbles can be devastating at close range. The bubbles are so tiny that they can penetrate even the smallest crevices, making the process ideal for parts which could not be cleaned by other methods. Note also that the process must be well controlled to minimise erosion of the surfaces of the parts being cleaned. The standard test of ultrasonic intensity in a cleaning bath is to immerse a standard foil strip for a set time, then remove it and count the number of holes!

CUTTING

Imagine a knife which moves itself backwards and forwards in a sawing action, thirty thousand times a second. True the distance moved is very small but the acceleration is so high that nothing can move with the blade or stick to it. Ultrasonic scalpels are used by surgeons where they want to cut without exerting any pressure. In industry ultrasonic cutting tools are used for products that are difficult to cut by other means.

The heat generated by the ultrasonic vibrations can also be useful. Some man-made fabrics are cut and simultaneously sealed using ultrasonic knives to prevent fraying.

ULTRASONIC MACHINING

Ultrasonics have been used in several ways for machining metals. Lathe tools may benefit from deliberately-induced vibrations to prevent "chatter" which compromises the surface finish of the finished component. Ultrasonic drills, used on very hard ceramics, work by grinding or eroding material away - a liquid slurry around the drill bit contains loose hard particles which are smashed into the surface by the vibrations, eroding material away and creating more loose hard particles

METAL FORMING

My own experience of power ultrasonics is mainly in this field. CarnaudMetalbox R&D (now a part of Crown Cork and Seal - the biggest packaging company in the world) and Loughborough University developed a new aerosol can using a number of novel metal-forming processes, starting with ultrasonic necking (i.e. reducing the diameter of the can at one end). The advantage of using ultrasonics in this case was to minimise friction between the can and the die, thus reducing the forming force. Without ultrasonics the force was so high that the can body would buckle and collapse during the necking process. With ultrasonics a 30% reduction in can diameter could be achieved in a single operation (in conventional necking processes the maximum is typically about 5%).

The ultrasonics were only effective when the vibrations were perpendicular to the surface - for a cylindrical can this meant developing a round die that would vibrate in the radial direction. As with other high-power applications, all tooling had to be resonant, so the desired mode of resonance was a uniform hoop expansion / contraction. We quickly found that while it was fairly easy to design a die to resonate in this mode at the frequency of the ultrasonic equipment, excluding other modes of vibration was a major challenge!

Another difficulty was that with the whole die expanding and contracting there was no convenient nodal (stationary) point which could be used for mouning it. This was solved by the use of a tubular mounting system which was itself resonant at the same frequency as the die.

The ultrasonic forming process went into production making small-diameter aerosol cans in a UK factory. The production line still runs intermittently, making promotional packaging for several prominent customers. One of its products ("Fleurs de Paris" parfum deospray can) won a silver in the 1997 Metal Packaging Manufacturers Association awards.

METAL WELDING

. Ultrasonics can be used to weld different metals together, without solder and flux or special preparation. The process is different to plastic welding in that the two components are vibrated parallel to the interface. This is a more intuitively logical method of generating friction between them, but frictional heating is not thought to be the prime mechanism of the process - the temperature needed to melt (or even soften) most metals would be very difficult to achieve. Instead the mechanism is thought to be diffusion-bonding: atoms of each part diffuse into the other when the two surfaces are brought together in close contact. The ultrasonics promotes this close contact by breaking down the surface oxide layers, allowing the "raw" metals to make contact.

The process has some limitations. It is only suitable for relatively small components (a prime example is welding connectors to car battery leads) since the power required to weld larger parts would be higher than can practically supplied by this method. Also the process tends to mark and deform the components, since high clamping forces and sonotrodes with serrated working faces must be used to grip the workpiece firmly.

PLASTIC WELDING

Plastic welding is used for a huge variety of products ranging from blister packs, cartons and small consumer goods up to car fuel tanks and dashboards. It works by generating heat exactly where it is needed - at the interface between the components to be joined. The components are clamped between a vibrating sonotrode and a fixed mounting. Strangely, the vibrations are usually applied perpendicular to the contact surface, although much of this vibration may be converted to in-plane movement. This also has the advantage that the clamping pressure will keep the sonotrode in contact with the component - serrated surfaces are generally not required. Best results are achieved when the components are clamped close to the interface ("near-field" welding) but if this is not possible then the process can still work at a distance ("far-field").

Staking, or insertion, is a variation of this process in which a metal part (generally a threaded bush) is driven into a hole in a plastic component, which then solidifies around it to form a permanent join. This is a convenient method of producing strong tapped holes in a plastic part.

More information:

SIEVING

Industrial sieves are normally agitated at low frequency to help the product to distribute itself evenly over the surface and to help the small particles go through. Vibrating the mesh at ultrasonic frequencies (in addition to this low-frequency oscillation) can improve the rate of flow dramatically, preventing the product from blocking the holes in the mesh and helping to separate the small particles from the large.

SINTERING

The powder-metallurgy process is used to manufacture top-quality steels and other metals. The powder must be packed as closely as possible before the sintering process begins to prevent the formation of voids or other weaknesses in the finished product. Published research papers indicate that a significant increase in the packing density can be achieved using ultrasonics. Can anyone confirm that this process is in production?

Fuses protect against overcurrent (too much current flow), however caused.

In a parallel circuit, the current flow is independent in each branch.

AS PER THUMB RULE THE CURRENT CARRYING CAPACITY OF WIRE IS 4 TIMES OF ITS CROSSECTIONAL AREA OF WIRE i.e. 10 sq.mm wire carrying maximum current 40 amp , 16 sq.mm carrying maximum current 64 amp ,

now amp convert in watt by multiplying by volt i.e. 240

16 sq.mm carrying max load 64x240= 15360 watt

Many lifts have the same functions. Thus, the four major load control functions found on a load lift are lift, lower, forward, and backward. Joystick Control Functions. 3-4. Joystick Control Functions (Button Pushed). 3-5. Service Brakes. 3-6 ... major contribution to safety if you, as the equipment users and operators: 1. ... Know that the machine can safety lift each load before attempting to lift. These are ...... Any problems discovered in the steps.

Obviously there is more than one way to do this.

VL = Ldi/dt Volts has units of Joules/Coulomb: J/C i has units of Coulombs/second: C/s

So di/di is C/s^2 L has units of J/C / C/s^2 = Js^2/C^2

Ic = CdV/dt => Ic/dV/dt = C/s / J/C-s = C/s * C-s/J = C^2/J C has units of C^2/J OR you could just type Q = CV => C = Q/V = C/J/C = C^2/J same answer

R = V/I => J/C / C/s = J-s/C^2

if your talking about a generator its not the hp of the engine its the size, rpm, and gearing of the generator motor

An 'isolation transformer' is a 1:1 ratio mutual transformer. It electrically isolates the secondary circuit from the primary circuit without changing the voltage level. A bathroom shaver socket uses an isolation transformer.

Incomplete data: To have an accurate result - please provide the following;

1. Voltage Rating - Low Votage or Medium Voltage Applications?

2. Efficiency

3. Power Factor

4. Distance - One way distance from source

5. Location and method and arrangement of Installation

6. Allowable or acceptable voltage drop

7. Type of cable - PVC or XLPE cable with same size has different ampacity