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Electrical Wiring
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4,935 Questions
For 6600 v Ht 1400000 watt Ac motor Find full load current?
The equation you are looking for is, amperage when kilowatts are shown. This is for three phase systems. To change watts to kilowatts divide watts by 1000. Amps = kW x 1000/1.73 x Volts x pf.
Use .8 for pf on large motors.
Why different electrical devices have different fuses and how the fuses are different?
The current flowing through a cable supplying a load or loads depends on the combined power of those loads, and the size of the cable is chosen according to the anticipated load. If the cable is overloaded, then it will draw excessive current (an 'overload current') and overheat, and its insulation may eventually fail, and present a fire hazard. If one or other of the load devices develops a fault, then that device may draw significantly more current (a 'short-circuit current') than it should and it will fail. So, cables are subject to over currents -i.e. 'overload currents' or 'short-circuit currents'.
A fuse is an over current protective device. It is designed to disconnect the cable supplying a load or loads in the event of an overload or short-circuit current occurring either in the cable or in the loads. By doing so, it protects the cable as well as the load, from overheating and prevents the possibility of a fire.
All fuses work on the same principle. A fuse carriercontains a fuse link, or fuse element, which is connected in series with the cable and its load. When an overload current occurs, the fuse link melts, and creates a break in the circuit, disconnecting the cable. The fuse link is carefully manufactured so that the larger the over current, the faster it melts.
Fuses are rated in amperes, according to the maximum current they can continuously carry without melting, and are manufactured in a range of standard current ratings. What makes each fuse rating different is the cross-sectional area of their fuse link; the greater the cross-sectional area, the higher the current rating.
In your home, individual circuits are each protected by a fuse*, sized according to the current capacity of the individual circuit. These, in turn are protected by a larger fuse which protects all the circuits. The larger fuse is designed to operate only if one of the individual circuit fuses fails to operate quickly enough. By fusing individual circuits in this way, an over current should only affect an individual circuit, without affecting any of the healthy circuits.
There are a great many different types and design of fuse, according to their application and the magnitude of system voltage they are to operate. Fuses designed to operate on low voltage systems are physically quite small, whereas fuses designed to operate of high-voltage systems are physically quite large -but they all work on the same principle.
*In residences, fuses are now being replaced by miniature circuit breakers (MCBs), which can be reset after they have operated, unlike fuses which must be replaced.
How do you measure core loss in a transformer?
Core loss is also called "No-Load" loss. To measure the core lose simply you need variable AC supply, Wattmeters, Ampere meters and Voltmeters. The basic principle to perform this measurement is to supply the transformer with its nominal voltage and then record the Watt or Kilo watt values. You will need precision current and voltage transformers to supply your wattmeters, voltmeters and ampere meters. There is a term called "Form Factor" which should be measured in order to identify how sinusoidal is your supply voltage and based on the value of this Form Factor you need to apply relevant corrections to the measured values. For power transformers normally we record no load values between 90% and 110% of rated voltage. Based on the test circuit configuration you may use "2 or 3 wattmeter" arrangements for 3 phase transformers. For further information you can check out my website at www.eonce.com and if you need more information you can simply fill the form in "Contact" page on the website. Hope this helps. B.M. Mirzaei, P.Eng.
What is a dry-type transformer?
Electric company high voltage transformers used in the utility grid are typically insulated by being immersed in a tank of oil, and cooled by natural convection (circulation) of the oil. A "dry type" transformer is not immersed in oil, and is cooled by air convection or by fans.
Can you use a 9volt 500 milliamp transformer for a door bell?
The key is the door bell specification. They typically run on a 24 VAC transformer. You can certainly hook it up and try it with 9 volts, but it probably won't work as intended. 24 Volt transformers are relatively cheap.
What are hair straighteners made of?
just kidding...
No really im serious.
Will a ground fault interrupter work at any outlet with only 2 wires?
Yes. GFCI receptacles do not rely on a ground conductor to work. They sense any difference between current flowing in the hot wire and current returning in the neutral wire. Under normal circumstances, these two currents will be exactly the same. If there is a difference, then some of the current is flowing from the hot to somewhere else, possibly through a person to ground. This causes the GFCI to trip. The National Electric code even permits an old 2-wire receptacle with no ground wire to be replaced with a GFCI 3-prong receptacle. No ground wire is used, and the GFCI must be labeled "No Equipment Ground". See NEC Article 406.3(D)(3)(b) and (c). This is the only legal way to install a 3-prong receptacle in place of a 2-prong without running a new ground wire.
Name one household items that use a battery as a source of electric current?
Alarm Clock
Hair Dryer
Disco Ball
A lot of things.
A: A DELTA transformer is a 1:1 voltage transfer delta to Y IS 1:2 voltage transfer. That is for 3 phase system, If the phases are not exactly matched or the voltage is not exactly right then on a Y setup there will be circulating current at the common node.
Radio Shacks 25 ohm rheostat works very well to the point where on the slow end, you have to give it a kick start if you turn on the power when it is on that side. If it is already running, it will continue to run (no load) at the low end.
Will an ac unit run on modified sine wave?
The unit should run OK on a modified sine wave since motors are not that sensitive to the waveform. Efficiency might be slightly reduced.
The real problem may be in starting the unit. If the input does not have enough power to allow the compressor to start properly and it stays running on the start winding, it could burn up the start winding. Checking the current input with a clamp-on style amp-meter should show if it is drawing excess current by running on the start winding.
Does the size of a capacitor matter?
Yes, the size of a capacitor "matters" just as much as the size of a resistor "matters". In both a capacitor and a resistor "size" refers not only to the electrical value of the item but to its current-carrying capacity: a small resistor will burn up if you try to push too much current through it. A big resistor will be able to carry a much higher current than a small one having the same resistance value.
Similarly, a small capacitor will be destroyed if you try to push too much current through it and a big capacitor will be able to carry a much higher current than a small one, even if both have exactly the same capacitance value. Capacitance values are measured in Farads (F), microFarads (uF) and picoFarads (pF). Just as a resistor has "Resistance " measured in Ohms, a capacitor has "Capacitive Reactance" or "Impedance", measured in Ohms.
The Impedance of a capacitor varies with the frequency of the alternating current passing through it. (This is quite different behavior to a resistor: the Resistance of a resistor does not change with the frequency.) If you look in a book about electrical engineering components you will be able to learn how the Capacitive Impedance is calculated according to the frequency. "The impedance of a capacitor is inversely proportional to the frequency - that is, for very high-frequency alternating currents the reactance approaches zero - so that a capacitor is nearly a short circuit to a very high frequency AC source. Conversely, for very low frequency alternating currents, the reactance increases without bound so that a capacitor is nearly an open circuit to a very low frequency AC source. This frequency-dependent behaviour accounts for most uses of the capacitor." [From Answers.com]
Will dielectric prevent water from getting in a connection on a transmitter antenna?
The best material to use on these types of connections is a rubber amalgamation tape. This can be purchased at any electrical supply house. After applying the rubber tape overlay it with ordinary electrical tape. The electrical tape has UV protection that will stand up under the sunshine and protect the rubber tape. When the electrical tape starts to look dried out and starts to crack just re install new electrical tape, the rubber tape will be alright and not need to be replaced.
How do you convert 230v single phase stove from England to 220v Canadian voltage?
You should be able to use it as is (assuming the plug matches your outlet). It will just run a little bit cooler at 220 volts vs. 230 volts.
What does a Voltmeter do in a circuit?
A voltmeter measures the voltage present in the circut. Voltage is the amount of energy available to push charges through an electric circut.
There are many kinds of materials which can be used but currently the element most used to make semiconductors is Silicon. Silicon is not a natural semiconductor so it has to be "doped" with very small amounts of other materials to make it have semiconducting properties. That's enough to say for now, unless someone else wants to just dump a complete answer here! To prepare a full answer to this obvious exam question you should do your own research on the Internet (Wikipedia perhaps?) and/or in technical libraries!
Isolation transformers are used to protect people working on transformerless equipment, where there is a 50-50 chance that the equipment's metalwork is at mains active voltage (110/240 V).
Plugging in to the transformer "floats" the equipment, so that the metalwork can be safely connected to ground, and remove any voltage on it.
An ELCB relies on detecting the imbalance between active current and neutral current that occurs when you touch a wire of metalwork that's at mains potential.
But, on the secondary of the isolation transformer, you decide which is active and neutral.
It is possible to wire the ELCB into circuit on the secondary side of the transformer, just as you would for a normal installation.
Be aware that you must now connect one of the transformer secondary wires to gound for the ELCB to work (at least, that's the case here in Australia), so you are back into the 50-50 chance of live metalwork, unless you fit a reversing switch that lets you ensure that the metalwork is connected to neutral.
But you need to understand that an ELCB only protects you from active-to-ground shocks, it DOES NOT protect you from active-to-neutral shocks, and there is no current equipment that can.
I STRONGLY SUGGEST that you consult with a licensed electrical contractor to work out what you are trying to achieve.
Electricity gives you one chance.
How do you convert kwh to CO2 tons?
The amount of CO2 generated from electricity (kWh) is dependant upon the way the electricity is generated. Burning a barrel of oil to produce electricity yields far more CO2 than generating the same amount of electricity from wind or water. One should contact their electricity provider to get a break-down of how the electricity is generated.
What will be the starting current of a 335hp Sqcage motor on no load?
Across the line starting of a motor can be as high as 300% of the full load amps.
What is an RCD cut the current to a circuit?
RCD cut the current to the circuit while preventing the electric shock
Look on the motor's chart for "Locked rotor current" its going to be high because the motor is trying to overcome infinite inertia. Any motor will draw 8 - 10 times its rated current upon start up because you are overcoming inertia. It takes more energy to start any system than it does to keeping it running.
Who sets standards for motor overload protection?
In Canada it is the CSA, Canadian Standards Association that checks for safety of electrical devices. After testing and when approved, the device will have a CSA designation on the equipment. By law, a Canadian electrician is not allowed to make a connection to any electrical device that doesn't have a CSA certification label attached.
Which type of circuit the parallel circuit are use?
they are used for more power than a series circuit so you should use this one.
