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What size conduit is needed for 4 wires three phase 200 Amps and one neutral?
Wiki User
∙ 9y ago
A three phase four wire system, the neutral is included in the wire count. It is the fourth wire so no extra neutral needs to be counted.
In North America a 3/0 copper conductor with an insulation factor of 75 or 90 degrees C is rated at 200 and 225 amps respectively. The electrical code states that a 53 mm or 2" diameter conduit can have up to five 3/0 conductors pulled into it.
Wiki User
∙ 9y ago
Wiki User
∙ 9y ago3" or larger. A 2 1/2 will only pass 3, 350 MCM. But bigger is always better.
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Why do you balance single phase loads across a 3-phase supply system?
On a Delta 3-phase you connect the single phase loads between pairs of the 3-phases. Warning both sides of these loads will be hot! You may want to use 3 isolation transformers so that the real loads have a neutral line.On Y 3-phase you connect the single phase loads between one of the 3-phases and neutral.In each case to balance the loads, try to put similar loads on each phase (or pair of phases).
How do you convert 380v 3 phase to 220v 3 phase?
Mathematically, just divide 480 by the square root of three. Electrically, 480V refers to the line-to-line value of a three phase system. For example, measure the voltage across A-phase and B-phase and you'll get 480V. 277V is the line-to-neutral value. Measure the voltage across A-phase and the neutral conductor and you should get 277V.
What is the difference between Load Current Line Current and Phase Current?
A load current is a current drawn by an electrical load. In other words, it is the current flowing from the source to the load.For a single-phase system, a line current is a current flowing through the line, or 'hot', conductor, while the current through the neutral conductor is called the neutral current.For a three-phase system, the three 'hot' conductors between the load and the source are called 'lines' and, so, the currents passing through them are called 'line currents'. For a three-phase system, loads are either connected between line conductors (delta-connected system) or between each line and the neutral (star- or wye-connected system), and represent the phases -so the currents passing through the loads are called 'phase currents'.For a balanced three-phase system, the line current is 1.732 times the value of a phase current, where the phases (loads) are connected in delta. For phases (loads) connected in star (or 'wye') the line current is numerically-equal to the phase currents.
Would voltage in a three phase supply change if neutral wire is disconnected?
No, The voltage will not change. The neutral is basically a ground and is used in conjunction with the phases to create another voltage and act as the return line in an electrical system. "Depending on the system that you have". If you have a 480 volt and used a neutral with it you would have 240 or 277 volt. The 277 volt is what is normally used in office lighting. If you have a 208 or 240 three phase system using a neutral you end up with the 120 volts that is used for just about all normal lighting, receptacles and general use devices used everyday.Additional AnswerWhile the supply voltage wouldn't change, the voltage across each phase of an unbalanced load may change if that load is unbalanced.
What is the maximum neutral current for a three phase delta star system?
It is either a delta or a star, it can't be both. A delta system doesn't have a neutral so the question must be about a star system. A high neutral current happens for example when one line is disconnected, and the neutral current then equals the current in the other two lines, which is the same current as when two lines are disconnected leaving only one line.There might be ways of calculating how to make the neutral current larger by using unusual power factors, but the above is a useful working maximum that allows all four wires of a four-wire star system to be the same size.AnswerThe term, 'delta-star', refers to a three-phase transformer connection in which the primary windings are connected in delta while the secondary windings are connected in star (wye). This is the standard three-phase connection, in Europe, for distribution transformers. Single-phase loads are connected to the secondary between alternate lines and neutral, in order to try to and balance the resulting load and minimise any resulting neutral current. Obviously, however, without having any specifications supplied, it is quite impossible to answer this question.
Can a three phase circuit be installed in the same conduit or in different conduits?
The conductors of any three phase circuit must be run in the same conduit. If the circuit requires a neutral, it must also run with the conductors in the same conduit. (If they were to be run in more than one conduit or raceway, the circuit would not operate properly.)
Do you need a neutral to install 480 volts 3 phase heater?
If the heater is rated as a 3 phase 480 volt heater then a neutral is not needed. If the voltage stated is 277 volts three phase then a neutral is needed.
If you were to pull 2 three phase circuits in the same conduit would you need more than 1 neutral and why?
If the load requires a single circuit breaker, as most three phase loads do, you need a separate neutral for each. This allows you to check the balance between each phase and the other phases as well as neutral, in order to detect a ground fault. It depends on the purpose of the three phase circuits - if this were CT cables, then yes, unless you intentionally over sized the ground wire. Otherwise this would cause unusually high voltage rise in the secondary of the CT during ground faults, which could lead to saturation (unless CT ratio is intentionally set high). As noted above, having separate neutrals helps to determine balance, although you can measure 3I0 from the phase currents for a similar relationship without actually looking at the neutral at all (some relays doe this for ground protection instead of directly measuring neutral current, see SEL's 351 for an example relay). No matter what, this would be highly irregular, and I wouldn't recommend scrimping on a neutral. In my experience, the more you move away from accepted practices (not to dampen ingenuity...), the more trouble you create for the future. If the loads were strictly three phase then there would not be any neutral needed. If from a three phase distribution panel the loads were three single phase loads then you can use one neutral for the three phase wires. This is a code rule that has to be adhered to. A same N, B same N, C same N and only in this combination. Conduit fill 4 wires, two three phase four wire circuits, conduit fill 8 wires.
When would you use a 4 pole transfer switch?
All that is needed for a three phase installation is a three pole, the neutral is not switched.
Why neutral cross section is half the phase in three phase cable while it has to carry current of summation of all phase..?
The current carried by the neutral of a three phase four wire system is the un balanced current. If the three phase system was completely balanced on all three phases there would be no need for a neutral, eg a three phase motor. This neutral current will be less that the phase current so a reduction in the neutral size is allowed.
Can you run different phases in the same conduit?
In the US, the National Electrical Code (NEC) will allow you to install single phase and three phase systems in the same conduit.
Condition of three phase in which there is no need of neutral?
A delta-connected system is described as being a three-phase, three-wire, system, and doesn't have a neutral. But a balanced star (wye) connected load (e.g. a three-phase induction motor) doesn't actually require a neutral.
What is the code ruling in the US on 3 phase branch circuits and the neutral?
A three phase system will have 3 phase branch circuits and no neutral.
Why neutral is not requied in 3 phase?
As far as I understand, you don't need neutral line for connecting appliances that is 3-phase compilant. You only need the neutral line to connect a single phase appliance, which you connect along with one of the three lines.
What is the formula to get neutral current in three phase transformer where three phase cureent are given?
Neutral current is the vector sum of the phase currents. You should be able to add up the phase currents from their polar quantities.
Why the neutral cable takes high current than the phase lines in three phase installation?
In a properly balanced three phase system, there is negligible current on neutral. If there is substantial current on neutral, then the system is not balanced and/or something is wrong.
What size conduit is needed for a 100 amp service according to the nec?
Three number three wires can be installed in an inch and one quarter conduit.
