DS8000 Service Documentation Version 7.5

MAP1130 PPS Fan Normal and Failure Modes

The PPS fans have multiple operation modes for normal as well as failure conditions.

MAP1130 Section-1

Procedure

The operation of the PPS fans is monitored and controlled by the microcode running in the PPS sequence module. The fan speeds are controlled individually and vary for normal operation. If an error condition occurs, a serviceable event is created and reported.

The PPS fans are controlled in 2 ways:

The speed of the fans is controlled in steps depending on the internal temperature sensors in the PPS modules and other conditions.
There are certain defined fan speed combinations for normal as well as error conditions. These combinations are shown in Table 1 and Table 2.

There are four fan speeds used:

Stopped (0 rpm)
Low (1860 rpm)
Medium (2820 rpm)
High (3800 rpm)

Table 1. Normal System Operation or System Standby Mode
Operating/Failure Condition	Top PPS Fan	Center PPS Fan	Bottom PPS Fan
Normal Mode	Low	Low	Low
Top PPS Fan failed	Failed	High	High
Center PPS Fan failed	High	Failed	High
Bottom PPS Fan failed	High	High	Failed
PPS to PPS Communication Failure	Medium	Medium	Medium
Battery charging in phase 1	Medium	Medium	Medium
On Battery Mode (Booster not installed)	Stopped	Stopped	Stopped
On Battery Mode (Booster installed)	Stopped	Stopped	Stopped

During PPS standby or fenced mode (208VDC and 5V/12V outputs are off), only the bottom and the center fans will operate.

Table 2. PPS Fenced Mode / PPS Standby Mode
Operating/Failure Condition	Top PPS Fan	Center PPS Fan	Bottom PPS Fan
Normal Mode	Stopped	Low	Low
Center PPS Fan failed	Stopped	Failed	High
Bottom PPS Fan failed	Stopped	High	Failed
PPS to PPS Communication Failure	Stopped	Medium	Medium