MAE-East still no generator

Sun Sep 8 16:26:38 UTC 1996

> In some telco facilities that do have AC generator backup, there are a few 
> seconds of down time while the generator kicks in.  In these spaces, AC 
> equipment will in all likelihood re-boot, while DC equipment stays up 
> through the transition.

That's why the PAIX is wired thusly:

             +--------+
Utility----->|Transfer|--+->Rectifier---->Battery---->Cage DC
Generator--->| Switch |   \
             +--------+    \
                         +======+======+
                        UPS    UPS    UPS
                         |      |      |
                        Transfer Switches
                                 \
                                  \
                                Cage AC

The batteries are sort of the capacitor in a huge DC power supply.  The
triple AC UPS is so that the electricians can do maintainance on one of
the UPSes while still leaving two others online.

Stephen was talking about dual rectifiers and a DC transfer switch but
I havn't been in that room for a while so I don't know if that happened.

It costs a lot of money -- almost as much as connectorizing the cross
connects -- but the goal is 100% uptime on both the AC and DC.