Amada S-2200CA, Operation Manual

Page: 183 / 210

IS-2200CA/4500CA INVERTER POWER SUPPLY
990-412 D-1
APPENDIX D
WIRE GAUGE SELECTION AND
CIRCUIT BREAKER SETTING
Sizing Power Input Lines and Transformer Input Lines
Due to the many possible combinations of transformer ratios, total secondary resistance and weld voltages,
all which have a direct relationship for cable sizing, this section assumes that the secondary current is at
its maximum peak current during the weld.
Wire gauges for the AC Mains and Output lines to the transformer must meet the following criteria:
a. For the 480 VAC or 380 VAC, 3 phase lines, the voltage drop must be less than 5%. Note also,
that if the input source drops by 1% then the cable allowance is reduced to 4% maximum. A table
is provided that gives the maximum length for the gauge selected (calculation is linear). Ampacity
must be equal to, or larger than the effective current based on NEC table 310-16.
b. For the Output lines to the transformer it is recommended that voltage loss does not exceed 1%.
A table is provided that gives the maximum length for the gauge selected (calculation is linear).
Ampacity must be larger than the effective current based on NEC table 310-16.
In general:
Size all cables for the maximum secondary current anticipated for your installation. Preferred would
be at full capability of 100 amps at 100% duty cycle.
Minimize cable length as much as possible.
If in doubt use a larger gauge cable.
Use the minimum number of connections as possible.
Insure that all connections are tight.
Formulas used:
I
EFF
= Output current times the square root of the duty cycle.
I
PH
= Resultant (I
EFF
x
0.817) current in each phase of the 3-phase input source.