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 the switch board and the other is located on the output choke. Excessive tem- peratures may be caused by a lack of cooling air or operating the machine beyond its duty cycle or output rating. If excessive operating temperatures should occur, the thermostats will prevent output from the machine. The yellow thermal light, located on the front of the machine, will be illuminated. The thermostats are
PROTECTIVE CIRCUITS
Protective circuits are designed into the
OVER CURRENT
PROTECTION
If the average current exceeds 450 amps for one sec- ond, then the output will be limited to 100 amps until the load is removed. If the peak current exceeds 600 amps for 150 ms, the output will be limited to 100 amps until the load is removed.
UNDER/OVER VOLTAGE PROTECTION
Protective circuits are included on the switch and con- trol boards to monitor the voltage across the input capacitors. In the event that a capacitor pair voltage is too high, or too low, the machine output will be dis- abled. The protection circuits will prevent output if any of the following conditions exist.
1.Voltage across a capacitor pair exceeds 467 volts. (High line surges or improper input voltage connections.)
2.Voltage across a capacitor pair is under 190 volts. (Due to improper input voltage connections.)
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3. Internal component damage.
