What is line current ?

M

mowhoong

Guest
I have a 10 hp power water pump which on 420 volts 3 phase, my
calcalation would be 12.8 A
line current, which mean each phase draw 12.8 A is that correct ?
Can any person help me in this question. Thanks
Regards
 
"mowhoong" <mowhoong@hotmail.com> wrote in message
news:3f920f74-555d-41b5-8058-9289e1b9c826@s37g2000prg.googlegroups.com...
I have a 10 hp power water pump which on 420 volts 3 phase, my
calcalation would be 12.8 A
line current, which mean each phase draw 12.8 A is that correct ?
Can any person help me in this question. Thanks
Regards
Click to expand...
420 volts phase to phase is about 242 volts to neutral. 10 HP is 7460
watts, so total current is 30.76 amps, or 10.25 amps per phase. But there
could be power factor and efficiency issues that would cause the current
draw to be 12.8 amps with output power of 10 HP.

Paul
 
"mowhoong"

Hi Paul. Thanks for your reponse. My water pump connection on 3 phase
do not have neutral, if I include the 0.8 on power
factor and efficiency it will have 16 A line current right ?


** Post your math - wanker.

Cos we all need a good laugh.



......... Phil
 
On Mar 11, 3:42 pm, "Paul E. Schoen" <pst...@smart.net> wrote:
"mowhoong" <mowho...@hotmail.com> wrote in message

news:3f920f74-555d-41b5-8058-9289e1b9c826@s37g2000prg.googlegroups.com...

I have a 10 hp power water pump which on 420 volts 3 phase, my
calcalation would be 12.8 A
line current, which mean each phase draw 12.8 A is that correct ?
Can any person help me in this question. Thanks
Regards

420 volts phase to phase is about 242 volts to neutral. 10 HP is 7460
watts, so total current is 30.76 amps, or 10.25 amps per phase. But there
could be power factor and efficiency issues that would cause the current
draw to be 12.8 amps with output power of 10 HP.

Paul
Click to expand...
Hi Paul. Thanks for your reponse. My water pump connection on 3 phase
do not have neutral, if I include the 0.8 on power
factor and efficiency it will have 16 A line current right ?
Regards
 
mowhoong wrote:
I have a 10 hp power water pump which on 420 volts 3 phase, my
calcalation would be 12.8 A
line current, which mean each phase draw 12.8 A is that correct ?
Can any person help me in this question. Thanks
Regards
Click to expand...
The US National Electrical Code gives 14A, 460V as typical for a 10HP
motor. Converting that would be 15.3A at 420V as typical.

Actual values depend on power factor and efficiency as mowhoong posted.
They also depend on whether the pump is developing 10HP. The power
depends on the head pressure.

No information plate on the pump?

--
bud--
 
On Mar 11, 4:59 am, "Phil Allison" <philalli...@tpg.com.au> wrote:
"mowhoong"

Hi Paul. Thanks for your reponse. My water pump connection on 3 phase
do not have neutral, if  I include the 0.8 on power
factor and efficiency it will have 16 A line current right ?

** Post your math  -  wanker.

  Cos we all need a good laugh.

........  Phil
Click to expand...
I'm laughing right now. You bring sunshine to my day.
 
On Mar 11, 6:51 am, mowhoong <mowho...@hotmail.com> wrote:
I have a 10 hp power water pump which on 420 volts 3 phase, my
calcalation would be 12.8 A
line current, which mean each phase draw 12.8 A is that correct ?
Can any person help me in this question. Thanks
Regards
Click to expand...
Yes, your answer is correct. Each phase draw 12.8A
 
"mowhoong" <mowhoong@hotmail.com> wrote in message
news:3f746831-64a5-4472-8169-49d728106e2d@i7g2000prf.googlegroups.com...
On Mar 11, 3:42 pm, "Paul E. Schoen" <pst...@smart.net> wrote:
"mowhoong" <mowho...@hotmail.com> wrote in message

news:3f920f74-555d-41b5-8058-9289e1b9c826@s37g2000prg.googlegroups.com...

I have a 10 hp power water pump which on 420 volts 3 phase, my
calcalation would be 12.8 A
line current, which mean each phase draw 12.8 A is that correct ?
Can any person help me in this question. Thanks
Regards

420 volts phase to phase is about 242 volts to neutral. 10 HP is 7460
watts, so total current is 30.76 amps, or 10.25 amps per phase. But there
could be power factor and efficiency issues that would cause the current
draw to be 12.8 amps with output power of 10 HP.

Paul
Click to expand...
Hi Paul. Thanks for your reponse. My water pump connection on 3 phase
do not have neutral, if I include the 0.8 on power
factor and efficiency it will have 16 A line current right ?
Regards

The effective phase-to-neutral voltage (which is the vector component in
phase with current at zero PF), is V(phase-phase) / sqrt(3). 10 HP = 7460
watts / 242 V = 30.8 A /3 = 10.2 A per phase. You should never see 16 amps
line current except on start-up. But a 0.8 factor on the 10.2 A gives 12.8
amps.

Paul
 
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