“Imbalance” as Per PoE Standards
A certain “resistance imbalance” (or “unbalance”), creates a corresponding “current imbalance.” We need to know how they are connected in PoE specifically.
The previous PoE standard (802.3af) says in Section 188.8.131.52 titled “Current unbalance”:
The specification for IUNB in Table 33-5 shall apply to the current unbalance between the two conductors of a power pair over the current load range. The 10.5 mA value is based on a simulated output current unbalance of 3 percent.
In Annex 33E (informative), the AF standard implies that this 3 percent current unbalance is caused by a 3 percent resistance unbalance:
The 3 percent cabling resistance unbalance is specified for the ISO/IEC cabling channel illustrated ...