What the 1500 W rating means for your protection design
The 1.5KE43C-E3/54: The 1.5KE43C-/54 is a 1500 W peak pulse power (1.5 kW) bidirectional TVS Zener diode from Vishay's TransZorb® series, housed in a through-hole DO-201AA (DO-27, Axial) package. For shorter pulses (8/20 µs), the peak power capability climbs significantly, so the 1500 W figure is a conservative baseline for comparing clamping performance across TVS families.
Voltage thresholds and clamping behavior
For a 48 V telecom bus or a 36 V nominal DC rail, this part clamps well below typical semiconductor breakdown thresholds, giving the protected device a comfortable margin. Being bidirectional (single channel), it clamps equally on positive and negative transients. This suits AC signal lines or DC rails where the polarity could reverse during a fault — no need to orient the part on the board. Power line protection is not supported — this is a signal- or low-power-rail protector, not a mains surge suppressor.
Obsolete — sourcing through independent channels
Vishay lists the 1.5KE43C-/54 as obsolete. The DO-201AA axial package means the laser etch and date-code traceability are the primary authenticity markers; any re-marked or sanded parts should be flagged before acceptance.