## 2.9 Power and cooling 

The z15 power and cooling system is a change from previous systems because the system is packaged in an industry standard 19-inch form factor for all the internal system elements. The configuration can be 1 - 4 frames (racks). Consider the following points: 

GLYPH<SM590000> The power subsystem is based on the following offerings: 

– Power Distribution Units (PDUs) that are mounted at the rear of the system in pairs 

– Bulk Power Assembly (BPA), as with previous systems 

GLYPH<SM590000> The system uses 3-phase power: 

– Low voltage 4 wire “Delta” 

– High voltage 5 wire “Wye” 

GLYPH<SM590000> No EPO (emergency power off) switch is used. 

z15 has a support element task to simulate the EPO function (only used when necessary to do a System Reset Function). 

GLYPH<SM590000> No DC input feature is available. 

GLYPH<SM590000> The air-cooled z15 server now has a radiator unit (RU) N+2 design for the pumps and blowers. 

GLYPH<SM590000> The water-cooled system option for the z15 server is only available with BPA-based systems. 

GLYPH<SM590000> No Top Exit Power feature is available because the 19-inch frame is capable of top or bottom exit of power. All line cords are 4.26 meters (14 feet). Combined with the Top Exit I/O Cabling feature, more options are available when you are planning your computer room cabling. 

GLYPH<SM590000> The new PSCN structure uses industry standard Ethernet switches (up to four) that replace the previous IBM System Control Hubs (SCHs). 

## 2.9.1 PDU-based configurations 

The IBM Z systems operate with redundant power infrastructure. The z15 is designed with a new power infrastructure that is based on intelligent (PDUs that are mounted vertically on the rear side of the 19-inch racks and Power Supply Units for the internal components. The PDU configuration supports radiator-cooled systems only. 

The PDUs are controlled by using an Ethernet port and support the following input: 

GLYPH<SM590000> 3-phase 200 - 240 V AC (wired as “Delta”) 

GLYPH<SM590000> 3-phase 380 - 415 V AC (wired as “Wye”) 

The power supply units convert the AC power to DC power that is used as input for the Points of Load (POLs) in the CPC drawer and the PCIe+ I/O drawers. 

The power requirements depend on the number of CPC drawers (1 - 5), number of PCIe I/O drawers (0 - 12) and I/O features that are installed in the PCIe I/O drawers. 

PDUs are installed and serviced from the rear of the frame. Unused power ports should never be used by any external device. 

