Advantages / Disadvantages of Parallel Feeder Conductors
Advantages / Disadvantages of Parallel Feeder Conductors
(OP)
I'm supplying 480/277 3PH 4Wire power to a new MCC (600A). I'm still a "rookie" engineer so please bear with me. What are the advantages/disadvantages of routing parallel phase conductors rather than a single phase conductor? Is it simply less expensive? Or is it some how "better" than routing one conductor per phase? Thanks in advance for any advice.
Sense
Sense






RE: Advantages / Disadvantages of Parallel Feeder Conductors
However, it is much easier (i.e. cheaper) to achieve required ampacities with parallel runs. The limiting factor in cable ampacities is heat dissipation, and doubling the gauge of a wire will often only add 25% or so to its ampacity, as heat loss is a function of surface area, not cross-sectional area.
Look at the NEC (or CEC) tables for ampacities, and you'll see what I mean.
RE: Advantages / Disadvantages of Parallel Feeder Conductors
RE: Advantages / Disadvantages of Parallel Feeder Conductors
Other fact is the ampacity does not increase proportinal to the size. A condutor with a cross sectional doule than other does not necessarioy carry double current but less than that. Which due to skin effect, for large diameter solid conductor most current will flow in outer area and not the center. This also has to do with heat dissipation capacity. as tinfoil suggested.
RE: Advantages / Disadvantages of Parallel Feeder Conductors
From a practical aspect, two conductors/ø would do for 600 amperes.
RE: Advantages / Disadvantages of Parallel Feeder Conductors
RE: Advantages / Disadvantages of Parallel Feeder Conductors
RE: Advantages / Disadvantages of Parallel Feeder Conductors
I think the shorter the run, the more critical the length is. In very short runs, the difference in length, flux linkage, etc between the conductors becomes a much larger part of the total impedance of each conductor.
For long runs, the slight differences in length become much less significant.
Also keep in mind that if one of the conductor draws more current than the rest, it will increase in temperature and this will increase its resistance. This effect does help mitigate **some** the length difference.
RE: Advantages / Disadvantages of Parallel Feeder Conductors
Bung
Life is non-linear...
RE: Advantages / Disadvantages of Parallel Feeder Conductors
I understand the logic behind equal lengths (equal sharing) but do you suppose mm's (say 3mm) difference in length would make any noticeable difference with cables ran, say 50-100 ft.?
RE: Advantages / Disadvantages of Parallel Feeder Conductors
Don
RE: Advantages / Disadvantages of Parallel Feeder Conductors
RE: Advantages / Disadvantages of Parallel Feeder Conductors
RE: Advantages / Disadvantages of Parallel Feeder Conductors
CT's feed an electronic module and the module reads out % imbalance on conductors.
Generally not used but the option would be there if it was needed to configure.
Rugged
RE: Advantages / Disadvantages of Parallel Feeder Conductors
Bung
Life is non-linear...