Catalyst 4500 4200W Power Supply Requirements

[MikeO5422]

I am new to understanding the power requirements for these devices. I have been using the power calculator tool and reading the 4500 installation guide here, which outlines the power supply requirements.

I would like to run a 4200W power supply with dual 120 inputs. To me the document is straight forward regarding this:

"Each chassis power supply should have its own dedicated, fused-branch circuit"

To me this means we need a total of two circuits. Both inputs on power supply A would connect to circuit 1, both inputs on power supply B could connect to circuit 2.

However, some folks are adamantly suggesting we need 4 circuits, on per power supply input. They are suggesting that the document is not correct. Other folks are suggesting that we could run two circuits, where input 1 on power supply A is connected to circuit 1, and input 2 is not connected to anything. Same for power supply B but on circuit 2.

I simply don't understand how they are coming to these conclusions. Has anyone here run a 4200W with dual 120 inputs? If so, what is the recommended number of circuits and plug configuration per circuit/psu?

[Reza Sharifi]

The 4200 has 2 AC-inputs, one should be connected to one power circuit or PDU and the other one should be connected to another power circuit or another PDU.  If you are not using any PDUs, then both power cords can directly plug into to receptacles.

HTH

[pieterh]

for full 4200W operation, the PSU needs two feeds that can supply 230V 20A

look at this from the installation guide.

Branch circuit requirement	Each chassis power supply should have its own dedicated, fused-branch circuit: For North America—15 A or 20 A For International—Circuits sized to local and national codes All Catalyst 4500 E-series AC-input power supplies require single-phase source AC. All AC power supply inputs are fully isolated. – Source AC can be out of phase between multiple power supplies in the same chassis, which means that PS1 can be operating from phase A and PS2 can be operating from phase B. – For high-line operation, the power supply operates with the hot conductor wired to a source AC phase and the neutral conductor wired either to ground or to another source AC phase as long as the net input voltage is in the range of 170 to 264 VAC. – Source AC can be out of phase between AC inputs on power supplies that are equipped with multiple AC inputs, which means that power cord 1 can be plugged into phase A and power cord 2 can be plugged into phase B.
Power supply output capacity	The power supply output capacity is dependent on the number of AC power cords (1 or 2) attached, the source AC voltage (110 VAC [low-line] or 220 VAC [high-line] applied to the power supply inputs, and the number of power supply power switches switched on or off. Note If source AC is applied to both two inputs, both inputs should have the same AC voltage.
1050 W operation	1050 W maximum with the following combinations of power cords and source AC voltage applied to the power supply inputs: One AC input is connected to low-line (110 VAC nominal); the second AC input is not connected to source AC or is switched off.
2100 W operation	2100 W maximum with the following combinations of power cords and source AC voltage applied to the power supply inputs: Both AC inputs are connected to low-line (110 VAC nominal) and both inputs are switched on. One AC input connected to high-line (220 VAC nominal); the second AC input is not connected or is switched off.
4200 W operation	4200 W maximum with the following combinations of power cords and source AC voltage applied to the power supply inputs: Both AC inputs are connected to high-line (220 VAC nominal) and both inputs are switched on.

[MikeO5422]

Thanks, something is still not quite right regarding the 4200W PSU in 2100 operation. I think what is confusing people is that it says two dedicated circuits per PSU are required. But it also says each individual outlet can pull 12amps. So 2x 15 or 20 amp circuits (1 per PSU) are not sufficient in a quad 120v configuration if each individual outlet can pull 12 amps, totaling 24 amps per PSU.

"Each chassis power supply should have its own dedicated, fused-branch circuit

-For North America—15 A or 20 A"

contradicts:

"12 A (maximum) @ 120 VAC or 230 VAC for each input"

I know the document says two circuits, but I feel like 4 are needed for quad 120 inputs.

[pieterh]

No you must read it as with 120V input you can NOT utilize the maximum power of 4400W

the PSU will drop down to "2100 W operation" mode.

1 input 120V 12A -> 1050 W operation

2 input 120V 12A-> 2100 W operation

1 input 230V 12A -> 2100 W operation

2 input 230V 12A -> 4400 W operation 

those are the maximum power the PSU wil offer to the chassis.

NB! 2 input 230V 12A @4400W ==>> there is NO redundancy! the load to the mains is spread among two feeds. if you want redundancy you still need two PSU's. and 4 feeds.

and with 2 PSU's 4x 120V 12A you have maximum power for 4200W, but redundant power for only 2100W