"show environment power" Question

[Pedro Morais]

Hello All,

After replacing some power-suplies we noticed the two of them show a slight diference in "Power Draw" and "Current". Everything else looks OK and I would say that there is no problem with the power-supplies. However just to be sure, please take a look at the below output and advise accordingly.

Before power-supplie replacement:

RP/0/RSP0/CPU0:EC-XPTO1#admin show environment power-supply

Wed Feb  1 12:52:44.659 WET

R/S/I   Modules         Capacity        Status

                         (W)

0/PM0/*

         host    PM      2100            Ok

0/PM1/*

         host    PM      2100            Ok

0/PM3/*

         host    PM      2100            Ok

0/PM4/*

         host    PM      2100            Ok

R/S/I   Power Draw      Voltage         Current

         (W)             (V)             (A)

0/PM0/* 424.3           54.4            7.8

0/PM1/* 375.9           53.7            7.0

0/PM3/* 455.2           54.2            8.4

0/PM4/* 509.4           54.2            9.4

--------------

Total:  1764.8

Power Shelves Type: DC

Total Power Capacity:                           8400W

Usable Power Capacity:                          8400W

Supply Failure Protected Capacity:              6300W

Worst Case Power Used:                          3420W

Slot                                                      Max Watts

----                                                      ---------

0/0/CPU0                                                        350

0/1/CPU0                                                        350

0/2/CPU0                                                        350

0/RSP0/CPU0                                                     235

0/RSP1/CPU0                                                     235

0/5/CPU0                                                        350

0/7/CPU0                                                        350

0/FT0/SP                                                        600

0/FT1/SP                                                        600

Worst Case Power Available:             4980W

Supply Protected Capacity Available:    2880W

After power-supplie replacement:

RP/0/RSP0/CPU0:EC-XPTO1#admin show environment power-supply

Wed Feb  1 17:27:07.093 WET

R/S/I   Modules         Capacity        Status

                         (W)

0/PM0/*

         host    PM      2100            Ok

0/PM1/*

         host    PM      2100            Ok

0/PM3/*

         host    PM      2100            Ok

0/PM4/*

         host    PM      2100            Ok

R/S/I   Power Draw      Voltage         Current

         (W)             (V)             (A)

0/PM0/* 226.3           53.9            4.2

0/PM1/* 672.0           54.2            12.4

0/PM3/* 433.6           54.2            8.0

0/PM4/* 433.6           54.2            8.0

--------------

Total:  1765.5

Power Shelves Type: DC

Total Power Capacity:                           8400W

Usable Power Capacity:                          8400W

Supply Failure Protected Capacity:              6300W

Worst Case Power Used:                          3420W

Slot                                                      Max Watts

----                                                      ---------

0/0/CPU0                                                        350

0/1/CPU0                                                        350

0/2/CPU0                                                        350

0/RSP0/CPU0                                                     235

0/RSP1/CPU0                                                     235

0/5/CPU0                                                        350

0/7/CPU0                                                        350

0/FT0/SP                                                        600

0/FT1/SP                                                        600

Worst Case Power Available:             4980W

Supply Protected Capacity Available:    2880W

Could anyone help on this? I would appreciate it!

Thanks!!

Pedro

[Alexei Kiritchenko · Accepted solution]

Hello Pedro,

On a fully loaded chassis (from power perspective) we can expect 15% variance in load sharing between modules. Lower the load, more variance we can get. So you current state is fine and we may not worry about it.

Regards,

/A

[Pedro Morais]

Thx Akiritch,

Just one question. Why were the values balanced (or more equal) before we change the power-supplies and now they aren't?  Any idea?

Once again thank for your help.

Regards,

Pedro

[Alexei Kiritchenko]

Hello Pedro,

Unfortunately, no definitive answer

There are enough variables involved (including that one power module is not precisely the same compare to another) with this sort of question we can't provide an exact answer. The voltage difference on any two sources will also vary due to facility loading and power system things that the we can't control.

Regards,

/A

[Pedro Morais]

Thanks for your help Akiritch!!!