What the ratings mean for your 24V or 48V bus protection
The 1.5KE440AH: Its 376V reverse standoff voltage means it sits across a DC bus rated up to that level without conducting leakage current, then clamps transients at 602V maximum to protect downstream semiconductors. With a breakdown voltage range starting at 418V minimum, this part is sized for 360-400V nominal DC rails — think traction inverter DC links, industrial drive bus capacitors, or 277VAC rectified supplies where the peak is around 390V.
DO-201 axial package and board integration
Through-hole DO-201AA (DO-27) axial package — the leads are 0.96mm diameter tin-plated copper, spaced 8.9mm apart. The body is 5.3mm diameter, 7.5mm long. Mounting requires a 1.2mm hole per lead; keep the trace width to the anode and cathode at least 3mm to handle the 2.5A peak pulse current without trace lift.