Every rack in a data center has a power budget, which is actually constrained by how much heat the HVAC system can pull out of the DC, rather than how much power is available. Nevertheless it is limited per rack to ensure a few high power servers don't bring down a larger portion of the DC.

I don't know for sure how the limiting is done, but a simple circuit breaker like the ones we have in our houses would be a simple solution for it. That causes the rack to loose power when the circuit breaks, which is not ideal because you loose the whole rack and affect multiple customers.

Another option would be a current/power limiter[0], which would cause more problems because P = U * I. That would make the voltage (U) drop and then the whole system to be undervolted - weird glitches happen here and it's a common way to bypass various security measures in chips. For example, Raspberry Pi ran this challenge [1] to look for this kind of bugs and test how well their chips can handle attacks, including voltage attacks.

[0] - https://en.m.wikipedia.org/wiki/Current_limiting [1] - https://www.raspberrypi.com/news/security-through-transparen...