The metering unit monitors inputs, which are collections of PDU power outlet groups. Depending on the PDU, an input might contain all of the outlet groups on the PDU, or a subset of the groups. The metering unit monitors the current, voltage, power, apparent power, and energy flowing through each input, not through each outlet group.
A metering unit input might also be divided into phases, which can either correspond to each power input lead in single-phase PDUs, or the separate phases in three-phase PDUs.
Single-Phase PDU Input and Outlet Group Relationship and Three-Phase PDU Input and Outlet Group Relationship show how the metering unit divides the outlet groups into inputs and phases.
These topics also help you understand the metering unit's web interface, SNMP messages, system log messages, and LCD screen. For example, if your rack contains a high-voltage 37 kVA PDU and the PDU's LCD screen shows that L2 of IN2 is using excessive current, the equipment connected to outlet group 7 needs attention.