Rockwell Automation Allen-Bradley 1305-AA02A, Руководство по установке

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2-6 Power Distribution
Transformer Impedance (in ohms)
Transformer Impedance (in ohms)
Example: The drive is rated 1 Hp, 480V, 2.7A input.
The supply transformer is rated 50,000 VA (50 kVA), 5% impedance.
Note that the percent (%) impedance has to be in per unit (5% becomes
0.05) for the formula.
0.22% is less than 0.5%. Therefore, this transformer is too big for the drive
and a line reactor should be added.
Z
xfmr
V
line line –
3 I
xfmr rated
–
⋅
----------------------------------------
⋅
% Impedance =
% Impedance is the nameplate impedance of the transformer
Typical values range from 0.03 (3%) to 0.06 (6%)
Z
xfmr
(V
line line –
VA
----------------------------------------
⋅
% Impedance =
)
2
or
Z
xfmr
V
line line
–
3 I
xfmr rated –
⋅
----------------------------------------
⋅
% Impedance =
% Impedance is the nameplate impedance of the transformer
Typical values range from 0.03 (3%) to 0.06 (6%)
ohms 102.6
7 . 2 3
480V
I 3
V
Z
rating input
line - line
drive
= = =
Ohms 0.2304 05 . 0
000 , 50
480
Impedance %
.
) (V
= Z
2
2
line - line
xfrmr
=
.
=
VA
% 0.22 0.00224
102.6
0.2304
Z
Z
drive
xfrmr
= = =