In my days of working with CTs, #1 rule was never power up a CT without a load, dead short is just fine. A CT will try to pass the secondary current and generate as much voltage as it needs to pass that current, theoretically, it will generate enough voltage to arc across the gap, but I never saw it happen. Another thing I experimented with was a low voltage, high current circuit breaker tester. I put 100 amps through CT and left it open to see what would happen. With the low voltage capability of the tester, with the CT shorted, it did pass the correct current, set at 100 amps, with the CT secondary open, it couldn't generate enough voltage to pass the current, so, if the secondary is open, it creates a significant impedance to current flow. On you 50/5 CT with a 100 ohm load, at a primary current of 50 amps,you should have 500 volts across the 100 ohm resistor and 5 amps flowing through it, generating 2500 watts of heat. If you have a 1 ohm load, you will still have the 5 amps flowing through the resistor, but just 5 volts and 25 watts of heat. and most of the instruments I ever worked with that used CTs had 0 ohms resistance. The power has to come from somewhere and it comes from the primary lead being measured.
Kinarfi
Another thing about CTs is they all have a ratio of xxx/5.