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Section 1
General Information
3-6 Receiving & Installation MN718
Line Impedance The Baldor Series 18H control requires a minimum line impedance of 3% (voltage drop
across the reactor is 3% when the control draws rated input current). If the incoming
power line has less than 3% impedance, a 3 phase line reactor can be used to provide
the needed impedance in most cases. Line reactors are optional and are available from
Baldor.
The input impedance of the power lines can be determined in two ways:
1. Measure the line to line voltage at no load and at full rated load.
Use these measured values to calculate impedance as follows:
%Impedance
+
(Volts
No Load Speed
*
Volts
Full Load Speed
)
(Volts
No Load Speed
)
100
2. Calculate the short circuit current capacity of the power line. If the short circuit
current capacity is greater than the published maximum short circuit current
ratings for the control, a line reactor should be installed.
Two methods of calculating short circuit current capacity are provided:
A. Method 1
Calculate short circuit current as follows:
I
SC
+
(KVA
XFMR
1000
100)
(%Z
XFMR
V
L
*
L
3
Ǹ
)
Example: 50KVA transformer with 2.75% impedance @ 460VAC
I
SC
+
(50
1000
100)
(2.75
460
3
Ǹ
)
+
2282 Amps
B. Method 2
Step 1: Calculate KVA short circuit as follows:
KVA
SC
+
(KVA
XFMR
)
(
%Z
XFMR
100
)
+
ǒ
50
.0275
Ǔ
+
1818.2 KVA
Step 2: Calculate short circuit current as follows:
I
SC
+
(KVA
SC
1000)
(V
L
*
L
3
Ǹ
)
+
1818.2
1000
460
3
Ǹ
+
2282 Amps
where:
KVA
XFMR
=Transformer KVA
I
sc
=short circuit current
Z
XFMR
=Transformer Impedance
V
L–L
=Input volts measured line to line
Summary of Contents for 18H Series
Page 1: ...SERIES 18H AC Flux Vector Control Installation Operating Manual 9 97 MN718 VECTOR DRIVE ...
Page 105: ...Section 1 General Information 5 18 Troubleshooting MN718 ...
Page 109: ...Section 1 General Information 6 4 Manual Tuning the Series 18H Control MN718 ...
Page 144: ...Appendix C Appendix C 1 MN718 ...