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another project... #130746 12/05/06 07:41 PM
Joined: Oct 2006
Posts: 12
J
JLC Offline OP
Member
OK here we go...

480V/3Ph/60Hz IN

OK just called My destributer technical support and got the MS coil amps. and its 8VA/120=.066666Amps.


1 - Blower Motor---------------4.5A
1 - Blower Motor Starter w/OL-- .06A(8VA)
1 - Dual Solenoid Valve---------.50A(60VA)
10 - Pilot Lights(7 max const.)--.17A
2 - Flame monitors(1A each)----2.00A
4 - Single Solenoid Valve-------.30A(10.1W each)
-------------------------------------
Total ======================7.53A(*480V=3614.4VA)
Transformer size===============3.03A(*120=363.6VA)

Is this right.?

What size fuses should i use on my main disconnect switch legs L1,L2,L3 ?

[This message has been edited by JLC (edited 12-05-2006).]

[This message has been edited by JLC (edited 12-06-2006).]

[This message has been edited by JLC (edited 12-06-2006).]

Tools for Electricians:
Re: another project... #130747 12/07/06 09:49 AM
Joined: Nov 2006
Posts: 348
I
ITO Offline
Member
For 3Ø (three phase) power calculations you use this:

480V x 1.72 (some folks use 1.732) which comes out to 825.6V
208V x 1.75 = 357.76V

This:
Quote
Total ======================7.53A(*480V=3614.4VA)

Should be:
3,614.4VA/825.6V = 4.38A


[This message has been edited by ITO (edited 12-07-2006).]


101° Rx = + /_\
Re: another project... #130748 12/07/06 10:49 AM
Joined: Oct 2006
Posts: 12
J
JLC Offline OP
Member
so instead of doing my calculations using 480 or 240 i should be using 480 x 1.72 = 825.6V and 208 x 1.75 = 364V

so after i add up the total VA being drawn by my components i then devide it by the 825.6 for 480v, or the 364 for 208. ok so my total amps drawn is:

7.53A*825.6V=6216.768VA Total ?

when i add the components that come off the trans. (everything but the blower) i get 3.03A*110=333.3VA ?

Is this right or am i missing a multiple for the 120V power from the trans. ?

also what would be the multiplier for a 360V/3PH/60Hz power supply?

if 480V = 480*1.72 = 825.6V
and 240 = 208*1.75 = 364V(357.76V/208V=1.72multiplier)

what does 360V =?
what does 120V =?

Also can i use 12awgBLK for my 3PH in?
14awgRED for 120Vpower for switches and lights on a US stationed electrical box?
with white as common? or should i be using different colors for switches and lights?

[This message has been edited by JLC (edited 12-07-2006).]

Re: another project... #130749 12/07/06 03:28 PM
Joined: Nov 2006
Posts: 348
I
ITO Offline
Member
I am not sure I am the one that needs to be giving you this advice; it looks like you are in over your head. I highly recommend you take a code study course, they are wonderful for getting these kind of fundamentals down. Every year Masters Electricians in my state are required to take a refresher code study course, so you will be in good company if your state does this too.


101° Rx = + /_\
Re: another project... #130750 12/08/06 01:48 AM
Joined: Nov 2006
Posts: 348
I
ITO Offline
Member
I an not trying to be a jerk, you seem smart enough to do this and I think you would benefit form a formal class. Its just good sincere advice.


101° Rx = + /_\
Re: another project... #130751 12/08/06 09:40 AM
Joined: Oct 2006
Posts: 12
J
JLC Offline OP
Member
Thanks for the vote of confidence, and i have taken a basic eletrical course but it was about 5yrs ago. I still have the books from it but not having someone here to rewalk me through it the formulas just dont add up if i try to figure them out. Some of this is just to verify what i think i know but i guess mostly its to know how to figureout the formulas so i can size my transformers correctly. i did start using the 1.732 multiplier for voltage and have made up a chart so i can add the info i know about a component and it will give me the other info im missing. but i still need to know if there is a multiplier for 120v and 360v.

Re: another project... #130752 12/08/06 10:23 AM
Joined: Nov 2006
Posts: 348
I
ITO Offline
Member
120V is single phase, so no multiplier.

360V is three phase, so yes use the multiplier.


101° Rx = + /_\
Re: another project... #130753 01/01/07 07:41 PM
Joined: Oct 2000
Posts: 2,721
Scott35 Offline
Broom Pusher and
Member
Just FYI, here are some 3Ø Voltage Equivalent values, for use when performing Power related equations:

  • 200V = 346,
  • 208V = 360,
  • 230V = 398,
  • 240V = 416,
  • 460V = 797,
  • 480V = 831,
  • 575V = 996,
  • 600V = 1039


Take the Line-To-Line Voltage for a 3Ø application, and multiply it by the Square Root of Three (* 1.732)

If the load value is to be figured across only Single Phase Circuitry (L-L ,or L-N), do not use the Three Phase Voltage values listed here - simply use the L-L or L-N Voltage value as applied.

Examples:

208Y/120V 3 Phase 4 Wire System.

A: (1) 10 HP, 208V 3 Phase Motor,
B: (1) 5 HP, 208V 1 Phase Motor,
C: (1) 1.5 HP, 115V 1 Phase Motor.

Volt-Amps for the following Motors:

A: (1) 10 HP, 208V 3 Phase Motor: 11,088 VA
* 30.8 Amps at 208V 3 Phase 3 Wire
* 30.8 x 360 = 11,088 VA

---------------------------------------------------------

B: (1) 5 HP, 208V 1 Phase Motor: 6406 VA
* 30.8 Amps at 208V 1 Phase 2 Wire
* 30.8 x 208 = 6406.4 VA

---------------------------------------------------------

C: (1) 1.5 HP, 115V 1 Phase Motor: 2300 VA
* 20 Amps at 115V 1 Phase 2 Wire
* 20 Amps x 115 = 2300 VA.

---------------------------------------------------------

Scott35


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

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