THEORY OF OPERATION
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THERMAL PROTECTION
Two normally closed (NC) thermostats protect the machine from excessive operating temperatures. These thermostats are wired in series and are con- nected to the Control Board. One of the thermostats is located on the heat sink of a switch board, and the other is located on the main choke. Excessive tem- peratures may be caused by a lack of cooling air or operating the machine beyond the duty cycle or out- put rating. If excessive operating temperatures should occur, the thermostats will prevent output from the machine. The displays will remain on during this time; and the yellow Thermal light, located of the front of the machine, will be illuminated. The thermostats are self- resetting once the machine cools sufficiently. If the thermostat shutdown was caused by excessive output or duty cycle and the fans are operating normally, the Power Switch (SW1) may be left on and the reset should occur within a
PROTECTIVE CIRCUITS
Protective circuits are designed into the Power Wave to sense trouble and shut down the machine before damage occurs to the machine’s internal components.
OVER CURRENT PROTECTION
If the average current exceeds 520 amps, then the peak current will be limited to 100 amps until the aver- age current decreases to under 50 amps.
OVER VOLTAGE PROTECTION
A protective circuit is included on the Protection Board to monitor the voltage across the input capacitors. In the event that a capacitor voltage is too high, the pro- tection circuit will prevent output. Also, in the event that a capacitor voltage is too low, the machine output is disabled and the “soft start” mode is repeated. The protection circuit may prevent output if any of the fol- lowing circumstances occur:
1.Capacitor condition is required. (Required if machine has been off for a long period of time and is connected for high input voltage operation.)
2.Voltage across a capacitor exceeds 370 volts. (High line surges or improper input voltage connec- tions.)
3.Voltage across a capacitor is under 170 volts. (Due to improper input voltage connections.)
4.Internal component damage.
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