THEORY OF OPERATION |
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PROTECTIVE CIRCUITS
Protective circuits are designed into the Invertec machine to sense trouble and shut down the machine before the trouble damages the internal machine components. Both overload and thermal protection circuits are included.
OVERLOAD PROTECTION
The machine is electronically protected from produc- ing excessive output current. Should the output cur- rent exceed 340 to 360 amps, an electronic protec- tion circuit will reduce the current to approximately 150 amps. Lincoln Electric refers to this current reduction as “Fold Back.” The machine will continue to produce this low current until the protection circuit is reset by removing the load.
Another protection circuit is included to monitor the voltage across input filter capacitors. In the event that the capacitor voltage is too high, the protection circuit will signal the Control Board to prevent output. The protection circuit may prevent output, if any of these circumstances occur:
1.Capacitor conditioning is required
(Required if machine has been off for prolonged periods of time.)
THERMAL PROTECTION
Thermostats protect the machine from excessive operating temperatures. Excessive temperatures may be caused by a lack of cooling air or by operat- ing the machine beyond it’s duty cycle or output rat- ing. If excessive operating temperature should occur, the thermostat will open and prevent output. The meter will remain on during this time. Thermostats will normally
If the thermal shutdown was caused by excessive output or duty cycle and the fan is operating normal- ly, the Power Switch may be left on and the reset should occur within a
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2.Line surges over 500 VAC
3.Internal Component damage
4.Improper connections