Over-Subscription Ratio (OSR)

In the case of Site/Transformer sharing, a power sharing group’s Over-Subscription Ratio is defined as the theoretical maximum power that could be delivered by all of the ports in the group (if they were all charging at full speed) divided by the configured power limit. Likewise, in the case of Panel/Circuit sharing, Over-Subscription Ratio is the maximum theoretical amperage divided by the configured amperage.

Example OSR Calculation for Site/Transformer Settings

The following is an example of OSR calculation for Site/Transformer settings:

  • Power Sharing Group (PSG) has 4 (Undefined variable: Products.p) ports, each with a max capacity of 6.6 kW.

  • Max capacity needed to operate these at full power = 26.4 kW (6.6 x 4).

  • OSR = Max Capacity Needed (kW)/Limit Set (kW).

  • If the power limit is set to 10 kW, then OSR = 2.64 (26.4/10).

Example OSR Calculation for Single-Phase Panel Settings

The following is an example of OSR calculation for single-phase panel settings:

  • A PSG has 4 (Undefined variable: Products.p) ports, each with a circuit breaker capacity of 40 A.

  • Max circuit capacity needed to operate these at full power = 160 A.

  • OSR = Max Circuit capacity (A)/Limit Set (A).

  • If the current limit is set to 120 A, then OSR = 1.33 (160/120).