Clamping, standoff, and the 19.4 V rail it protects
The 1.5KE24-E3/73: Reverse standoff voltage is 19.4 V — the TVS does not conduct below this, so a 19 V or 24 V nominal rail sees no leakage penalty during normal operation. That clamp voltage is what the downstream silicon sees; a 24 V-rated MOSFET or regulator with a 40 V abs-max survives this transient.
Package, mounting, and temperature envelope
The junction temperature range spans -55°C to +175°C, covering military and industrial ambient conditions without derating. Single unidirectional channel, no power-line protection — this is a signal or low-voltage DC rail TVS, not an AC mains suppressor.