Tens Of Thousands Of Amperes Of Short-circuit Current-can One Reactor Stop It? —The Core Principle Of Series Current Limiting.

The current can surge to tens of thousands of amperes in milliseconds in the event of a short circuit. What does this number mean? That means a normal transformer would burn out instantly, the circuit breaker might not even have time to trip over, and everything on the bus would be on the verge of collapse. What usually stops the beast is a silent series reactor. How does it do that?
Core Principle: Inductance is essentially a "brake" on current.
When a short circuit occurs, the current rises sharply and the reactor's inductive reactance "rises" immediately, producing a huge voltage drop ΔV = I × XL. This voltage drop absorbs most of the voltage in the short circuit directly and effectively inhibits the peak current flowing through the circuit breaker and downstream equipment. At the same time, since the voltage drop mainly occurs throughout the reactor, the remaining voltage on the busbar is maintained at a relatively high level, allowing user's equipment on the fault-free line to operate steadily.
In short: Short-circuit currents are not "eliminated" but "carried away" by reactors.
Split reactor: Not visible under normal conditions, visible when short-circuited.
Ordinary series reactors have the embarrassing feature thatthey also consume reactive power and generate voltage drops when they operate normally. Split reactors are much smarter. They have a center tap connected to the power supply and two branches connected to roughly the same load. In normal operation, the current in both arms flows in opposite directions, and the mutual inductance causes the equivalent reaction to be only half the size of a single-arm reactor, resulting in low voltage drop, low loss and near-invisibility. Once the single arm short-circuit, the single arm current surge, the mutual inductance saturates, the equivalent reactance the reactor immediately jumps to the value of the single arm, to maximize the flowlimiting effect.
This "normally trouble-free but emergency-friendly" characteristic has led to the widespread use of split reactors in power plant auxiliary power systems and 10-35kV substations.
Real-world achievement: A 500kV system withstood 40kA.
Don't think this is just theory. At Brazil's Tucurui hydroelectric power station in Brazil, the 500kV system connected the bus lines of phases I and II to the restricted-flow reactor, successfully limiting the short-circuit current to less than 40kA. In Brazil's Fumas project in Brazil, the 345kV system installed two limited-flow reactors at the MOGI substation feeder, which stabilized the the system's short-circuit current. In the New York 345kV system, four limited-flow reactors on the MS1 / 52 and 71 / 72 lines control short-circuit currents within the circuit breaker's breaking capacity. These are real-world examples of ultra-high pressure levels, not just lab numbers.
In domestic substation of 500kV, the series current-limiting reactor installed in the Shanghai Shijing substation has a rated current of 2400A and a a rated impedance 14 omega, which successfully controls the short circuit current of less than 50kA.
The cost is also clear: It's not a free lunch.
Series reactors is an uncontrolled current limiting device, and no additional control mechanisms is required. Its biggest advantages are simple operation, safety, reliability, convenient maintenance, long lifespan. However, the costs are also real: when strung together with the system, they increase the loss of reactive and active power and can cause voltage drops under heavy loads. The cost of manufacturing a single unit is close to $10 million. When the short circuit current is too high, the reactor alone may not be able to completely suppress it; it must be combined with a combination of grid layering and partitioning and bus segmentation.
So can a single reactor withstand short-circuit currents of tens of thousands of amperes? Yes, but it's not a lone hero; on the contrary, it's the strongest, quietest barrier in the power grid's current-limiting system.