what is the amperage of a 300 KW load ? thanks

[kak111]

Do you mean "neutral" wire's length ? (from load to supply)

No.

If we have 3-phase system with equal load in each phase, there is no current in neutral wire.

When calculating voltage drop in 3-phase cable , wire length is 2 * cable length.

 

[phatcreators]

if in 3 phase system, we provide 1 phase to a series network of 3 heaters of 16 ohms resistance & 2nd phase to a series network of 2 heaters of 17 ohms resistance & 3rd phase to the series network of other 2 heaters of 17 ohms resistance , then , what should be the total amps of the circuit & the amps per each phase ?

 

[kak111]

if in 3 phase system, we provide 1 phase to a series network of 3 heaters of 16 ohms resistance

Do you mean heat elements are in series between phases (400V)
P = 400^2 / 48 = 3.3 kW
P = 400^2 / 34 = 4,7 kW (2 pc`s )
Ptot = 3.3 + 4.7 + 4.7 kW >> about 12.7 kW

 

[danishdeshmuk]

so sorry for this particular post

 

[phatcreators]

Do you mean heat elements are in series between phases (400V)
P = 400^2 / 48 = 3.3 kW
P = 400^2 / 34 = 4,7 kW (2 pc`s )
Ptot = 3.3 + 4.7 + 4.7 kW >> about 12.7 kW

out of 3 phase supply, one phase is supplied to a series network of 3 heaters of 16 ohms resistance & 2nd phase to a series network of 2 heaters of 17 ohms resistance & 3rd phase to the series network of other 2 heaters of 17 ohms resistance. Also, the neutral is common to all of the 7 heaters (to their one terminal (leg) out of two terminals (legs)) ........

that means if we measure voltage across neutral & 1st phase (series network of 3 heaters of 16 ohms resistance) then we get 230 V AC , if we measure voltage across neutral & 2nd phase (series network of 2 heaters of 17 ohms resistance) then we get 230 V AC again but if measure voltage across neutral & 3rd phase (series network of 2 heaters of 17 ohms resistance) then we get 230 V AC again.

what type of connection is this ?

 

[kak111]

Should be like this...............

 

[phatcreators]

what i calculated was unbalance load i.e. almost 47 Amps for the one which had 3 heaters , 26 amps for 2nd one & 26 amps also for third ..........

connected in star you are right ..........

 

[munzir]

for 95mm2 single core 3 cables , what should be the size of the earth cable & for the neutral cable ?

what's the relation between phase cable & earth cable .... phase cable & neutral cable ?

thanks

 

[dineshdeshmuk]

if the load requires 100 mm2 3.5 core cable and we want to use 3 single core cables for each phases then what would be the size for each of the 3 single core cables for phases ? what size of neutral & earth cable would be required ?

thanks

 

[kak111]

what should be the size of the earth cable & for the neutral cable ?

Phase and neutral conductors ..... equal size

when phase conductor < 16mm² then earth conductor .... equal size
when phase conductor 16mm²...35mm² then earth conductor .... 16mm²
when phase conductor > 35mm² then earth conductor .... 0.5 x phase conductor

if separate neutral is not used then earth conductor must handle max. current in fail situations
( earth conductor minimum = phase conductor )

You must check above information from national requlations.


Neutral is a supply circuit conductor (that carries current in normal operation)
In a polyphase or three-wire (single-phase) AC system, the neutral conductor is intended
to have similar voltages to each of the other circuit conductors.

Ground or earth in a mains (AC power) electrical wiring system is a conductor that provides a low impedance path
to the earth to prevent hazardous voltages from appearing on equipment .
Under normal conditions, a grounding conductor does not carry current.

 

[danishdeshmuk]

what would be the total amps if per phase amps in a 3 phase system is 140 amps ?

what would be amps in a single phase system if the per phase amps in a 3 phase system is 140 amps ?

thanks

 

[kak111]

I dont understand your questions.
(what are you trying to find out)

If in 3-phase system each phase current is 140A
then total current in 3-phase is 140A / phase. (That´s the fact)

Total power is SQRT(3)*U*I*cos(Phi)

Three-Phase Circuits
**broken link removed**

 

[dineshdeshmuk]

calculation for cabling is done by considering connected load or by running load ??

 

[kak111]

or by running load ??????????????????????????

I can`t understand your question.
As shown in previous posts
calculated by given values.

 

[dineshdeshmuk]

i mean to ask when we calculate the size of a cable for a machine (a particular load) then do we calculate the total load (power) of the machine connected to it (considering all the total loads & all the power associated with the machine) or do we only consider the running amps (load or power) of the machine for cabling ............