PoE Delivered Power Budget
Estimate delivered PoE power as source power minus I²R cable loss and other fixed losses. Use the full loop resistance of the powered conductor pairs; protocol class and startup margins are not modeled.
Description
Estimate delivered PoE power as source power minus I²R cable loss and other fixed losses. Use the full loop resistance of the powered conductor pairs; protocol class and startup margins are not modeled.
PoE Delivered Power Budget: Estimate delivered PoE power as source power minus I²R cable loss and other fixed losses. Use the full loop resistance of the powered conductor pairs; protocol class and startup margins are not modeled.
When to use PoE Delivered Power Budget
Use this electronics calculation for a first-pass component, converter, signal, motor, or sensor estimate when the stated operating conditions and units match the device data.
- Source power (W)
- Required number input.
- Cable current (A)
- Required number input.
- Loop resistance (Ω)
- Required number input.
- Other loss (W)
- Required number input.
How PoE Delivered Power Budget works
Estimate delivered PoE power as source power minus I²R cable loss and other fixed losses. Use the full loop resistance of the powered conductor pairs; protocol class and startup margins are not modeled. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.1
- Cable Loss W
- The resulting cable loss w returned as a number.
- Delivered Power W
- The resulting delivered power w returned as a number.
Limitations and assumptions
- PoE power budgets must match the IEEE class, power at the sourcing and powered-device interfaces, pair set, cable resistance, temperature, startup classification, and conversion efficiency. Nominal switch power does not guarantee power at every endpoint.
- Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.
Alternative or Complementary approaches
Check the result against the current datasheet and worst-case operating corners, then verify the circuit or measurement with simulation and bench testing where failure matters.
References
-
Power over Ethernet — Wikipedia contributors
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