braking resistor parameter

kindly, we need to know the following "parameter" for the below braking resistor. any idea how to calculate it? or where can we find it?  

https://support.industry.siemens.com/cs/pd/213635?pdti=td&lc=en-QA   

Hello,

this is for braking resistor "mathematical" overload protection. I would say that this is not pretty important when you select your resistor correctly or even with margin

Usually resistors are supposed to heat up to max temperature up to 120s and can stand high short-time overloads.

I think you may put for 1 s the peak power of your resitor, i.e. 12 kW

Please check below difference between Siemens braking resistors and their competitor ones.  

If the Siemens resistor peak power is 120 kw, what should be its thermal transient response in Watt Sec?  For the competitor one, it is more then one million.   

1. 12 kW was a mistake I meant 120kW - the peak power of your resistor, so you could type in 120kW*s

2. Actually this value is even higher because the resistor can stand huge short-time overloads. 120kW*s is a "pessimitic" value, which is surely enough for any application for providing guaranteed overload protection for you resistor, and I would use it if I have no further tech details, like in your case

3. If you put this value too small, then you could probably get the drive tripped with a trip message like "Braking resistor overload" or "overheated" or something like that, but actually the resistot stays cold or just warm. In this case you can increase this value in the draive parameter. This is like empirical approach.

4. To be exact this value is very much dependant of some external conditions, like ambient temperature, ambient air flow, and is given of course for definite ambient conditions. From this point of view it's very good to have reasonable margin for this value, i.e. to type in smaller values

to be safe, i have put the parameter value equal to half the competitor's, which will be 500 000 watt-second.  now the machine is running ok.  to be monitored.  thanks