Simon K

Hi all,

I know there's a few IT guys on this site, and many engineers / electrial dudes, so thought I would see if you could help.

Ive a SAN switch with only one PSU in it which isnt good in regards to resiliance. Normally each server or switch has two PSUs, each being fed by a separate power source.

So, I had this idea of cutting a kettle lead, and stitching on another plug , i.e.

PDU-A---- Plug -----

=== |--------connector/server

PDU-B---- Plug ---

Is this possible ?? IVe had a few people tell me it isnt, but Im sure it would work. Each plug would go into a separate PDU, meaning if I lost one, the other plug would still provide power. Someone mentioned to me that this would mean both PDU circuits would be joined together, which would causes issues. Another person mentioned I would have drawback ( what ever that is ). Im sure if you had some relay / diode to prevent current going down the other cable would stop this.

Perhaps this is a Dragon's idea / invention ? ;-)


So, anyone here help ?? Even better a website that sales them ?? I had a meeting yesterday and mentioned it, and got shot down big time. Infact, the way people responded to my idea, was like I stood up and pulled out my john thomas. So, If I could buy one, prove my point, would be great :-)

SBK

dunx

iTrader: (3)

It's AC power a diode isn't going to help, and you could just buy two UPS's for a pair of PSU's ?

dunx

Simon K

How would I be able to install two UPS into one power connector that goes into the switch ? Where I use USPs / PDUs / ultimately I have to join the power sources together, to then plug into the switch.

SBK

BlkKnight

Can't you just run the UPS's in line?

Coffin Dodger

http://www.maplin.co.uk/2-way-iec-mains-lead-26767

As for cutting a kettle lead and stitching another plug on - please don't!

If you do whoever does the PAT testing in your office will throw it in the bin when he sees it

Simon K

Coffin.

Thanks for the link, I need something like this, but instead of two connectors and one plug, two plugs and one connector.

So, if one plugs blows / disconnects, the unit will still have power from the other plug.

Two UPS = a lot of £££££. Ive had a few poeple say this type of cable wouldnt work, but Ive got no hard evidence to suggest why. Perhaps I should go and test it on an old ex / decomissioned server.

SBK

Coffin Dodger

No you can't do that, very dangerous & illegal.

You would need some sort of active device to take two power supplies as a primary / secondary and for it to fail over to the secondary if the primary goes down. As mentioned some sort of UPS device would probably do this

stevep360

iTrader: (20)

One ups dual powered by 2 plugs connected to 2 different resilient power rails

HHxx

I would highly recommend you NOT run it like that!!!

You still only have 1 psu that could fail on your san switch.

What does 2 plug to a single input gain you... (If it were safe to do anyway....)
- The 2 feeds HAS to be on the same phase.
- If you have a power outage, be it from a UPS/building/campus wide, it would still affect both circuits.
- If you plug this cable into 2 UPS's, the UPS's had better be in sync!!! If they switch to battery, they will drift out of phase if not start out of phase! If you think 2 UPS's are expensive, the ones that can sync up normally start in the £10,000's range. Double conversion UPS's.
- What size fuse would you run in each plug if you are using BS1363A? Run say 13A's, the circuit would need at least 26A to blow making a fault possibly a major event. Fire maybe? Your fuse sizes would always be at least double of what is required by your equipment.
- Most 'kettle' IEC plug/socket are only rated to 10A.
- As mention, both circuits will be interconnected. Diodes also as mentioned will not isolate it as it is AC. They would have to be electrical isolated. I doubt your short power lead would power one of the other ring/circuit without catching fire.

I'm seriously trying to talk you out of doing this!

Does the san switch not have the option of a second psu? If it doesn't, buy another san switch for path resilience. All your kit should be backed up on UPS for clean shutdowns anyway, especially your storage.