15
Hookup 1
_______ Amps
3 _______ Amps
Hookup 3
______________
Amps
3
______________
Amps
Hookup 2
______________
Amps
3
______________
Amps
Hookup 1
50 Amps
– 46 Amps
4 Amps
EXPLANATION & EXAMPLES
Here is an example of current readings
at maximum pump loads on each leg of
a three-wire hookup. You must make
calculations for all three hookups.
To begin, add up all three readings for
hookup number 1, 2, and 3.
Divide the total by three to obtain the average.
Calculate the greatest current difference from
the average.
Divide this difference by the average to
obtain the percentage of unbalance.
In this case, the current unblanace for
hookup number 1 is 8%.
Hookup 1
T1 = 51 Amps
T2 = 46 Amps
T3 = 53 Amps
TOTAL = 150 Amps
Three Phase Motors
Below is a worksheet for calculating current unbalance on a three-phase hookup and selecting
the proper wiring. Use the calculations in the left-hand column as a guide.
Hookup 1
50 Amps
3 150 Amps
Hookup 1
.08 or 8%
50 4.00 Amps
FIGURE HERE
Hookup 1
L
1
to T
1
=
________
Amps
L
2
to T
2
=
________
Amps
L
3
to T
3
=
________
Amps
TOTAL = ____ Amps
Hookup 2
L
1
to T
3
= ____ Amps
L
2
to T
1
= ____ Amps
L
3
to T
2
= ____ Amps
TOTAL = ____ Amps
Hookup 3
L
1
to T
2
= ____ Amps
L
2
to T
3
= ____ Amps
L
3
to T
1
= ____ Amps
TOTAL = ____ Amps
Hookup 1
____ Amps
– ____ Amps
____ Amps
Hookup 2
________
Amps
–
________
Amps
____ Amps
Hookup 3
________
Amps
–
________
Amps
____ Amps
Hookup 1
____ or ____%
____ ____ Amps
Hookup 2
____ or ____%
____ ____ Amps
Hookup 3
____ or ____%
____ ____ Amps
LCPTL003_CR I&O_Rev0104.qxd 1/26/2004 11:58 AM Page 15
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