How to determine if installed braking resistor is correctly sized
Compute the thermal capacity of the resistor's mass. Pure silicon is 1.6 picoJoules per degree C per cubic Micron (yes--cubic micron).

A 1,000 watt resistor, mostly made of porcelain with resistive-element around the porcelain core, likely has about 0.1meter^cubed volume.

This is 100,000microns^Cubed, or 10^15 cubic microns.

Multiply 10^15 cubic microns by 1.6 picoJoules per degree C per cubic micron, and your
heat capacity is a 1,600 joules/degree C.

If you dump 100 joules into that resistor/core, the resistor/core will heat up by only
1/16th of a degree. The thermal timeconstant, given avout 1cm thickness of the porcelain core produces 1.14 second TAU .... is 1.14 seconds.

Again, your resistor can store lots of energy, with a 1.14 second thermal time constant.