Network controlled power strip

[iflymyhelishigh]

Hey guys. I have been looking around, and I have finally come up with my ideal idea for my server setup. I currently run a bunch of servers in my "data" center, and I need a way to shut them off and turn them on, or to cut power completely to them if DDOS or something occurs. For those of you who don't understand servers, ignore what I just said. The basic project is to have a rackmounted power strip, which can be controlled by commands through a server.

Now, I already know how I'm going to do that, I'll literally set up a server inside of the rackmount box, but I'm still deciding on the power output options. I have a couple options for power which I'll list below.

1. Standard Magnetic Relay
2. Solid State Relay
3. Servo and Switch
4. Screw the idea

1. Standard Magnetic Relay. I do not like this idea at all, because some of my servers will be running for 24/7 and I have a feeling that one day one of the coils might burn out, ultimately shutting down one of my servers.

2. Solid State Relays sound great, but I am deciding on them. How reliable are they? Do you think they can run in the "on" or "off" position for 24/7/365?

3. Servo and Switch. I could possibly setup a lightswitch inside of the box, and yes, this sounds corny, but control it using a servo that can switch it on and off. This is probably the best way, but it's extremely bulky.

4. Screw the idea. this pretty much gives itself away, the idea is stupid.

If you guys have any other suggestions for power control, or can help me decide, please post!

 

[Alexsgarage]

Screw the idea, LOL.

I think that a solid state relay would be a good choice, an SSR will last longer than an electromechanical relay because there are no moving parts. Look at the data sheet to see how many amps the relay is rated for and select one to fit the needs of the servers, you might also need to heatsink it. SSRs will also be easier to drive because the transistors will need a low voltage to saturate whereas a conventional relay may need up to 120V to turn it on.

 

[Sceadwian]

A relay won't wear if it's on 99% of the time, relays are generally rated on switching cycles. The UPS supplies of all those high density server racks still use relays for their primary switching element because they're reliable. Generally speaking if a preventative device such as that switches on or off more than once a month something is seriously wrong with the system.

 

[iflymyhelishigh]

OK. Sceadwian, I assume that they use relay that can have a normal on position for mains supply, then the current will switch over to backups. That would eliminate the problem with wearing out relays. the problem is, even if I do that, I might have to have a server shut off for long periods of time.

Solid State relays sound great, but they're so expensive -.-

Are there any that can handle a server's wattage and are cheap? like really cheap. lol

 

[iflymyhelishigh]

Do SSRs need to be heat sinked?

 

[Sceadwian]

So expensive? They're not that bad.

 

[iflymyhelishigh]

Alright. I'm officially stuck. Is it possible to make a PCI card that can control relays? I have 2 of these 12 volt RadioShack 20 amp relays.

 

[blueroomelectronics]

If you think SSRs are expensive doing a PCI circuit will cost more.

 

[iflymyhelishigh]

No, you see, I originally could only find some of those 200 dollar Solid State Relays, which made me go "WTF?!"

I've developed a very simple circuit using a 2N2222 to control the relay, and I've made it so that I can control 9 relays from 1 parallel port. Rather than using a parallel port card, I'd rather interface directly onto the card using RJ-65 ports.

 

[blueroomelectronics]

What card are you talking about with RJ-65?

The simple parallel port is probably your best bet. You could try USB with an FT245R IC

 

[ke5frf]

Do SSRs need to be heat sinked?

While not a requirement for light duty applications, a must for continuous duty with medium to high power.

The coil of a relay is rarely, rarely, rarely ever the failure, unless you are using the cheapo "12 volt RadioShack 20 amp relays" or it is defective to begin with. I assume your servers are in a temperature controlled environment, so excessive environmental heat shouldn't be a concern.

.....Besides, it sounds like you are looking for a way to shut off power and bring it back up from a control computer. Being that this is a controlled shut down system, why not use NC relays and have the energized coil OPEN them, this way the coil isn't energized but on occasion. Just an idea....

Mechanical relays usually fail after repeated contact arcing from cycling, they become pitted. As he said earlier, static duty isn't likely to cause a failure, though sometimes a defective contact point with a tissue-thin gap will cause trouble, but this is unlikely as well. (That's why you stay away from RadioShack).

SSRs OTOH have their trouble as well. I am QUITE familiar with SSRs in high power control circuits, especially temperature control. It is one of the more common replacement parts that I have to keep on hand. This of course is round the clock cycling with 20 amp circuits, but they do fail. Heat sink compound can get dry and ineffective over time. Surges, combined with power converted to heat, combined with time, will eventually do one in. The one good thing about them is precision control for systems that cycle at high frequencies. A mechanical relay wouldn't last two weeks in the circuits I work with. This doesn't sound anything like your application.

 

[iflymyhelishigh]

aha. Well, it turns out that Radioshack just rebranded them, they are actually OEG PCLH-202D1S relays, not too bad. I am going ot have them normally closed, because both is possible. So now the circuit is built, I need to find a way to trigger it using a parallel port with my available supplies. A transistor. haha

 

[iflymyhelishigh]

Alright. I've got the schematic and circuit, er, I actually lost it, but I'll find it again later.