What is the maximum amount of electrical energy that can be delivered durning a short circuit for low voltage 230v/400v
Tom, Not sure if what you're asking relates to the Maximum electrical energy (Voltage and Amps) that can occur during a short circuit through a properly protected electrical circuit (protected by a circuit breaker, etc.) or if the question is for the maximum amount you could potentially get from a short circuit on a 230V or 400V electrical line to ground OR another electrical line/supply.
IF the circuit is a 230V-AC circuit protected by a double circuit breaker, you could see the entire Voltage (230V-AC) and up to the full Ampere rating of the circuit breaker, (20, 30, 40, 50, etc Amps) during a short circuit condition to Ground.
IF the circuit is a 400V-AC circuit protected by a double circuit breaker, you, again, could get the entire Voltage (400V-AC) and up to the full Ampere rating of the circuit breaker protecting the circuit, when shorted to Ground.
Now, IF the short condition involves one of the above line voltages AND you are having it shorted against another Voltage/Amp circuit, the total potential Voltage and Amps you could experience, would basically be the sum of the two Voltages (and Amps) of the two (2) circuits being put into a short condition. So you would/could see a potential short circuit of whatever voltage is available, depending on what and where the short circuit is occurring.
By way of example, I've seen a 240V-AC 60 Amp circuit shorted to another 240V-AC 60 Amp circuit and the resultant "short condition caused enough damage, due to the voltage and Amps provided, to melt and weld the machinery's electrical connections, rendering the unit a total loss, not to mention that the person that caused the short to occur, received a face-full of melted copper metal bits all over their face and body. Thankfully they were wearing safety glasses, and their eyesight was saved, albeit, with some temporary blindness caused by the extremely bright flash and explosion.
The examples provided assume a properly working/functioning circuit breaker protection. However, if the circuit breakers are faulty, it is possible to recieve much higher vlotages and Amps, since there would be no protective circuit breaker that could trip the power off. In that case, the Main circuit breaker becomes the fail-safe protective device and that could have a much higher Amp rating, thus the maximum Voltage/Amps would be limited by the Main electrical ciruit breaker and electrical supply available at the location where the short circuit occurs.
This could be MUCH higher Voltage and extremely high Amps, depending on the situation and equipment involved.
If you have more information about the particular situation, please post a follow-up comment and I'll provide you with some more info.
I hope you find this Very Helpful and best regards!