These things look like MOVs, but you cant use an MOV in the circuit like that. not in series with the supply voltage. at TB7 i have 240 volts. TB6 feeds 3 dc power supplies. TB8 feeds a monitor and another power supply. TB8 has 240 volts. The #1 25R 3A was blown apart. So, no 240 volts at TB6. I just cant figure out why a MOV or thermister would be in that circuit.
bq). PTC thermistors can be used as current-limiting devices for circuit protection, as replacements for fuses. Current through the device causes a small amount of resistive heating. If the current is large enough to generate more heat than the device can lose to its surroundings, the device heats up, causing its resistance to increase, and therefore causing even more heating. This creates a self-reinforcing effect that drives the resistance upwards, reducing the current and voltage available to the device.
bq). NTC thermistors can be used as inrush-current limiting devices in power supply circuits. They present a higher resistance initially which prevents large currents from flowing at turn-on, and then heat up and become much lower resistance to allow higher current flow during normal operation. These thermistors are usually much larger than measuring type thermistors, and are purposely designed for this application.
bq). "The inrush current limiter is normally placed in series with the diode bridge, motor, or other components of a system that benefit from inrush protection. For added protection, two Surge Limiters can be placed in series."
The components resembling MOVs are identified as thermistors, specifically used for current limiting and inrush current protection in power supply circuits. These thermistors have ratings such as 25 ohms at 3 amps and 1 ohm at 20 amps. Unlike MOVs, thermistors can be placed in series with supply voltage to limit inrush current by initially presenting high resistance that decreases as they heat up during normal operation. They serve as self-resetting protective devices, replacing fuses in some applications. Additionally, thermistors, known as positors in TVs and monitors, can function as timing devices in circuits like degauss coils. The discussion clarifies that these components are not MOVs but PTC or NTC thermistors used for inrush current limiting and circuit protection. Summary generated by the language model.
