Power load calculating for 7188 or 9188 power distribution units

Learn how to calculate the power load for power distribution units.

Rack-mounted 7188 or 9188 power distribution unit

This topic provides the power loading requirements and proper loading sequence for the 7188 or 9188 power distribution unit.

The IBM® 7188 or 9188 rack-mounted power distribution unit (PDU) contains 12 IEC 320-C13 outlets connected to six 20 A circuit breakers (two outlets per circuit breaker). The PDU employs an inlet current that allows a variety of power cord options that are listed in the following chart. Based on the power cord that is used, the PDU can supply from 4.8 kVa to 19.2 kVa.

Table 1. Power cord options
Feature code	Power cord description	KVa available
6489	Power cord, PDU to wall, 4.3 m (14 ft.), 3-phase, Souriau UTG, IEC309 32 A 3P+N+G plug	21.0
6491	Power cord, PDU to wall, 4.3 m (14 ft.), 200 - 240 V ac, Souriau UTG, IEC309 63 A P+N+G plug	9.6
6492	Power cord, PDU to wall, 4.3 m (14 ft.), 200 - 240 V ac, Souriau UTG, IEC309 60 A 2P+G plug	9.6
6653	Power cord, PDU to wall, 4.3 m (14 ft.), 3-phase, Souriau UTG, IEC309 16A 3P+N+G plug	9.6
6654	Power cord, PDU to wall, 4.3 m (14 ft.), 200 - 240 V ac, Souriau UTG, Plug type 12 plug	4.8
6655	Power cord, PDU to wall, 4.3 m (14 ft.), 200 - 240 V ac, Souriau UTG, Plug type 40 plug	4.8
6656	Power cord, PDU to wall, 4.3 m (14 ft.), 200 - 240 V ac, Souriau UTG, IEC309 32 A P+N+G plug	4.8
6657	Power cord, PDU to wall, 4.3 m (14 ft.), 200 - 240 V ac, Souriau UTG, Plug type PDL plug	4.8
6658	Power cord, PDU to wall, 4.3 m (14 ft.), 200 - 240 V ac, Souriau UTG, Plug type KP plug	4.8

Loading requirements

The power loading of the 7188 or 9188 PDU must follow these rules:

Total power load connected to the PDU must be limited to below the kVa listed in the table.
Total power load connected to any one circuit breaker must be limited to 16 A (derating of circuit breaker).
Total power load connected to any one IEC320-C13 outlet must be limited to 10 A.

Note: The load on the PDU when a dual line configuration is used will only be half the total load of the system. When calculating the power load on the PDU, you must include the total power load of each drawer even if the load is distributed over two PDUs.

Proper loading sequence

Collect power requirements for all units that will be connected to the 7188 or 9188 PDU. See Server specifications for specific power requirements.
Sort list by total power required from highest power draw to lowest power draw.
Connect highest power drawer to outlet 1 on circuit breaker 1.
Connect next highest power drawer to outlet 3 on circuit breaker 2.
Connect next highest power drawer to outlet 5 on circuit breaker 3.
Connect next highest power drawer to outlet 7 on circuit breaker 4.
Connect next highest power drawer to outlet 9 on circuit breaker 5.
Connect next highest power drawer to outlet 11 on circuit breaker 6.
Connect next highest power drawer to outlet 12 on circuit breaker 6.
Connect next highest power drawer to outlet 10 on circuit breaker 5.
Connect next highest power drawer to outlet 8 on circuit breaker 4.
Connect next highest power drawer to outlet 6 on circuit breaker 3.
Connect next highest power drawer to outlet 4 on circuit breaker 2.
Connect next highest power drawer to outlet 2 on circuit breaker 1.

Following these rules will allow the load to be distributed more evenly across the six PDU circuit breakers. Ensure that your total power load is below the maximum listed in the table and that each circuit breaker is not loaded above 15 A.

PDU load sequence schematic