What this 1500 W Zener TVS actually protects
The 1.5KE56A-E3/51: It clamps a transient at 77 V maximum when the surge current hits 19.5 A, and its 47.8 V reverse standoff means the protected rail can sit at that voltage without the diode conducting in standby. The DO-201AA axial package (also known as DO-27) is through-hole mounted — it handles the thermal pulse of a 1.5 kW surge without lifting a pad, but the leads need to be bent and inserted into a board or terminal block, not reflowed.
Obsolete — sourcing through independent channels
Vishay lists this part as Obsolete.
The 1500 W peak pulse rating (10/1000 µs) is the energy the diode can absorb in a single surge — it does not mean continuous 1500 W. For a 24 VDC supply rail, the 47.8 V standoff gives headroom above nominal, and the 53.2 V minimum breakdown ensures the TVS does not clamp during normal ripple. If the downstream components have a 80 V absolute maximum, this TVS keeps them inside the safe operating area.