Electrical Engineering

Ungrounded wires which are not connected to any electrical source can have a voltage due to the influence of electric fields. Electric fields, through capacitive coupling, will give rise to voltages on ungrounded metal parts. The electric fields from nearby power lines or electronic lighting ballasts form a kind of ad-hoc capacitor with the ungrounded metal which gives rise to a voltage measurable with a high impedance voltmeter. (Low impedance analog voltmeters will not read this voltage because the voltage has no current source and so the voltage collapses to zero when placed in parallel with a low impedance.) Voltage from capacitive coupling is commonly encountered by electricians when a spare set of wires is run adjacent to a live circuit and may be referred to as "phantom voltage." When using a high impedance meter, the placement of a shunt resistor in parallel with the test leads will bleed off capacitively coupled voltage and give an accurate measurement. Capacitively coupled voltages do not present a shock hazard except in unusual cases involving extremely high fields in specific industrial environments.

No. An LED (light emitting diode) allows current to flow in one direction, thus it cannot alternate as is implied by "an AC source".

ANSWER: YES they can. Any diode can work with AC They can work from AC line directly. My overhead light in my kitchen are across 120 AC now for 8 years. But then again I know what I am doing

i think its also like the form of torque by its shake with that of osillating

The frequency is changed by varying its speed, and the the voltage is changed by varying its field current.

Ohm's Law doesn't apply to an incandescent lamp, regardless of its power rating. This is because the filament is manufactured from tungsten which is a 'non-ohmic' or 'non-linear' conductor, which means that the ratio of voltage to current changes for variations in voltage. For Ohm's Law to apply, this ratio must remain constant for variations in voltage.

2

megger are available in ac &dc

A fixed capacitor can be used for power-factor correction for a single-phase ac appliance such as an induction. One of these can also be used to suppy a phase-altered current to the starting winding on the motor.

In electronics fixed capacitors are used in shunt for decoupling, which earths any ac voltages on a dc-carrying wire, or in series for blocking dc and passing ac signals between stages in equipment.

Anything over 3400 watts is ok for a converter to power the product. The converter's rating is a maximum value so it can power anything up to 3400 watts.

In general the waveforms measured by these instruments is sinusoidal (sine waves).
A square wave is made up of many fundamentals and would possibly cause errors.
The meter measures from 2Khz to 15 Mhz.
Most radio frequency applications deal with sine waves.

In the heater you will have two wires. You should then have 2 supply wires from the panel, and 2 wires from the thermostat. The neutral (white) supply wire should go to one of the wires on the heater. The hot (black) supply wire should connect to one wire from the thermostat. The other wire from the thermostat will connect to the other wire from the heater.

Easy, you just switch it off!

A conductor of electricity is said to be a superconductor if it has some resistance at room temperature but when it is brought down to a critical temperature i.e. to a very low temperature such as -270 oC or so , it loses its resistivity completely.

We have not yet found a substance that works as a superconductor at room temperature but a lot of research is on-going. The aim is to try to find metal alloys or other substances that will behave as superconductors at temperatures which are much closer to room temperature than to absolute zero.

Existing known superconductors are metal alloys which have been discovered to have no electrical resistance when they are at low enough temperatures, typically close to absolute zero i.e. 0 Kelvin or about -273o C.

So "superconductivity" is a property of certain substances at given temperatures, not of any substance at any temperature.

2 is larger than 0.8

A "dry" contact is a contact that is not initially connected to a voltage source. It could be stand-alone, such as a pressure switch mounted on a boiler. Or, if the contact is mounted as part of an electrical unit that has a power source, then the "dry" contact has no pre-wired electrical connection to that power source. For example, a magnetic motor starter may have an extra contact that is not connected to the control circuit that starts and stops the motor. However, when the motor starts, the "dry" contact changes state, because the mechanical action of the starter moves the contact. This "dry" contact could then be wired to devices/circuits that are separate/remote from the motor starter circuits. I do not recognize the term "no volt contact" but I suspect that it is the same thing. A specific type of dry contact in the USA is a "form C" contact which is a three wire contact: Normally Open(NO), Normally Closed (NC), and a Common (C).

The purpose for the fan is to cool the radiator, therefore, the blades would, by definition, turn TOWARD the direction that the part of the blade that is closest to the engine... Therefore, it would push the air toward the radiator, particularly, when the truck is not in operation. As the previous poster indicated, it is generally clockwise.

DC Voltage

it is the flux which is flowing opposite to the main field flux and demaganetize it...

in order to eliminate this demagnetiszing component we have to connect the compensating winding in series with the armature winding which develop the flux in it oppose to the demagnetizing component

There is no difference. Slo-Blo is just a trademarked name for a time delay fuse.

You "could" run a 120V 5A window AC unit off a 12V deep cell battery but, assuming 100% efficiency (something you can never get), you would need an inverter or motor-generator set and 50A out of the battery to run, and maybe 5 or 10 times that to start.

Use a non-contact method such as infrared to measure the drum temperature, or mount a wireless, battery powered temperature transmitter to the drum.

Load cable generally means the final cable before the actual load. So on a clothes dryer the "Load Cable" would be the cable running from the outlet to the actual clothes dryer.