Where did you come up with the buffer switch not tripping, this is the first time I'm hearing this interpretation of the test. Once a ETS is tripped, all circuits are disables and the buffer switch would not make a difference. The ETSD is not meant to stop the buffer from being struck, but remove the power from the motor and set the machine brakes so buffer is struck at a the lowest speed possible. You just need to be able to verify the etsd is tripping before the buffer switch.
