Uninterruptible power supply for servers with one data center power input?

Question

Batteries

Good afternoon.
We have a data center, at the time of the test switch several racks fall, the IT department finds out that they have equipment with one power input, with one power supply. The power was switched after the UPS in the distribution cabinets from one power cabinet to another, equipment with two power supplies, each of which is powered from a separate cabinet, will not notice such a switch, but with one unit it simply turned off.
Are there any devices similar to a second-tier UPS, but without using a battery for 2 inputs, without interrupting the power supply. The inputs are out of phase. That is, it is necessary to bring 2 guaranteed inputs to the supposed piece of iron, and get one at the output without interrupting the power supply.
You can, of course, install full-fledged second-tier UPSs with batteries, but manufacturers should probably develop such solutions for the case of equipment with a single input.
Who faced a similar problem? Or can't do without a battery?
Name of IT equipment provided:
WS-C3750G-24TS-1U
CISCO2811
WS-C2960S
WS-C2950T
WS-C2960S WS-C3560X- 48PF
-S WS- C3750G
-24TS-1U
Polycom RMX 2000
Polycom appliance sever
Polycom Capture Server ! But they sent more pieces of iron, ibm 306 DL320 x306 SF V210 StorEdge s1 DL360 GS1910 SF V210 x335

DL320 G6
x346
StorEdge s1

Answer 1

Considering that half of this is Cisco switches (and my favorite WS-C2960S) that have a special input on the rear panel (number 3 in the illustration) for connecting a special redundant power supply ( Cisco RPS 2300 ), I recommend that the IT department at least look through the manuals for the hardware they use.
Half of the problems will disappear.