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Electrical Wiring
Ask questions here about proper wiring and electrical installation here.
4,935 Questions
What is the purpose and advantages of shielded cable?
Shielded cable is commonly used for routing of audio, video, and rf signals. The grounded shield surrounds one or more inner conductors that carry the often low level signals and prevents spurrious external electromagnetic events from inducing an unwanted additional signal into the center conductor(s). Idealy, the signal cables should all be commonly grounded only at one location. Otherwise, a condition known as ground loop can occur which can actually degrade the signal and possibly even damage connected devices. In some cases where even more noise protection is needed, a two wire plus shield method known as balanced wire is used. The signal is applied across the two center conductors and at the recieving end applied to a balanced transformer with its center tap connected to ground and the shield. Therefore, any induced noise will (presumably) be equal in both signal conductors and will cancel itself at the transformer while the out of phase signal passes right through.
What is the length of time that a motor can safely run on starting and full load current?
It depends on the insulation provided in winding, motor can safely run on full load current. and over that it may burn but depends on cooling system of the motor. Motor can burn if insulation fails, failure of insulation depends on only the temperature rise.
The kV.A (not 'kva') rating is the total apparent power of the machine. So a 75 kV.A machine is 25 kV.A per phase.
What would be the 3 phase voltage on a frequency of 50 Hz?
Single phase and three phase voltages are not related to the frequency at which the voltage is generated. The frequency at which voltages are generated is governed by the speed of rotation of the generating device.
How do you pick the right fusible link?
Fuses are based upon the size of the wire of the circuit that it is to protect. The wire is sized by the amperage of the connected amperage load of the circuit.
When the switch is on there is 12.2 volts when you crank it is only 0.4 volts in the system?
What system? Some circuits go to 0 volts when cranking. If you are reading voltage at the battery, then the battery is dead.
On what voltage does a shunt trip coil usually operate?
It depends on what part of the world it is in and what the usual control voltage is in that part of the world.
What is more important insulators or conductors?
Conductors and Insulators. In a conductor, electric current can flow freely, in an insulator it cannot. Metals such as copper typify conductors, while most non-metallic solids are said to be good insulators, having extremely high resistance to the flow of charge through them.
What is the purpose of the third wire?
By "third wire" I believe you are speaking of the ground wire. Its only purpose is to ensure that the over-current device, which is the breaker or fuse, operates property when a fault exists in the circuit. Without the ground wire you increase your risk of injury, death, or property damage.
It is there for your protection. Do not remove it. Always choose to use it when it exists.
What are the names of the different kinds of splices and joints used for electrical cables?
Some common types of electrical splice:
Rat-tail, Western Union, fixture, knotted tap, staggered splice.
Some common types of electrical joint:
Screw terminals, braided eyelets, crimps, sty-cons, plugs and sockets, insulated screw connectors, wire clip connectors (wire push-ins), twists inside wire nuts, plain wire soldered joints, soldered wire joints to posts and soldered legs for integrated circuits on printed circuit boards.
What are advantages and disadvantages of an electrical charge?
This seems like a question from an electrical course, and is probably best answered by your course materials.
It's your test question, not ours, and there won't always be someone to ask the answer of. Earn your diploma.
THE FIRST THING IS TAKE THE READING OFF LOAD AND SEE IF THEY ARE BALANCED. HAS THE MOTOR BEEN RECENTLY REWOUND? GET A MOTOR REPAIR COMPANY TO LOOK AT THE MOTOR AND SEE IF IT HAS BEEN WOUND CORRECTLY. IF THE STAR-DELTA WORKS CORRECTLY IT SHOULD START IN STAR FOR ABOUT FIVE TO TEN SECONDS AND GO INTO DELTA THIS IS DEPENDANT ON THE STARTING CURRENT THE MANUFACTURE OF THE SWITCH AND THE APPLICATION. CHECK ALL THREE PHASES ARE BALANCED AND IF THEY ARE THE MOTOR WINDINGS MAY NOT BE CORRECTLY WOUND. SOME HAVE STAR CONNECTIONS BUILT IN.LOOKING AT THE AMPERAGE THE LOAD REQUIREMENT IS ONLY A FRACTION OF WHAT YOU ARE GETTING SO IT LEAVES ONLY TWO THINGS I......MOTOR FAULT 2.....WHAT EVER THE MOTOR IS DRIVING IS PUTTING A MASSIVE PRESSURE ON THE MOTOR CAUSING IT TO OVERLOAD.
What is The meaning of Voltage 'V ab' is the voltage at?
V ab is the voltage between two nodes of the circuit. See also Kirchoff's Voltage Law. WHILE CORRECT IT REALY MEANS POINT a to point b in a circuit.
LED was not actually invented, but discovered. It was discovered by H.J. Round in the year 1907 through a crystal of silicon carbide.
What does 50 Hz mean or specify?
"50 Hz" is the shortened form of "50 hertz" which means "50 cycles per second".
50 Hz is the frequency of alternating current (ac) used by national electricity power services in many countries in Europe and elsewhere in the world whilst in USA, Canada and many other countries it is 60 Hz.
Will a fuse of a higher amperage rating have a higher melting point link?
No, a fuse of a higher amperage rating will not usually have a higher melting point link. The higher amperage fuse will use a wider link or a link of larger diameter.
What is a typical rated amperage for an electrical range?
In North America a 40 amp breaker is used on 240 volts. W = A x V = 40 x 240 = 9600 watts. That is the maximum that can be drawn from the circuit but usually only one or two burners or the oven are ever used at one time reducing the wattage load. On the back of the range there is a nameplate with all of the specification of your unit.
In what condition does a motor gets burnt out when running at rated load?
If overload is not the cause, then high temperature could be caused by blocking the cooling of the motor.
