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Discussion Starter · #1 ·
I run an internet hosting company. We’re looking to offer VERY low cost colocation services where customers send us their servers and equipment and we charge them for space, power and bandwidth. Typically the big unknown is power. A customer can send us a server that uses anywhere from 0.3amps to 6 or even more amps of AC 120v power. So our cost can vary dramatically as space and bandwidth are much cheaper than power. We’d really like to offer the low power consuming customers an amazing price which they deserve. And the high power consuming customers can be charged fairly for what they use.

So I bought a clampmeter testing tool from Graybar after they told me I could measure the current on live servers. I thought great, I can measure servers once a week and get an average usage. Then charge customers based on the readings. But it doesn’t work! I read the manual and it says I need a line-splitter. I looked online and found odd shaped line-splitters at about $15-30 each. Though I'm not sure they're what I need.

So I’m a little confused now. Can someone help me understand the equipment I need to accomplish what I want? Is there a better way to accomplish what I want?
 

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Yup, they're right. Your amp clamp meter won't work if you clamp it around both the hot and neutral so you need to figure out a way to just clamp it around the hot. I don't imagine you want to be pulling the receptacles out of their boxes to accomplish this so you will need to buy or build a splitter.

Like this maybe:

http://www.web-tronics.com/opaclinsplit.html

It looks like this one is wound to provide a x10 winding to provide more accurate measurements at low amp draw.
 

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Discussion Starter · #3 ·
I like that line splitter rabbitgun! Actually Pete over at tequipment.net gave me a ton of great suggestions. There is in fact a clampmeter that allows you to measure a non-split power cable!
http://www.tequipment.net/MeggerMMC850.html

A little expensive at $270, but worth it.

Pete also showed me some tools like the following:
http://www.tequipment.net/P3P4400.html

What looks really interesting is some of the Hokia line of logging tools that allow me to sample the current readings very frequently from a server over the LAN.
 

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There are a whole host of devices to do the things you want, the extent all depends on the money you have to spend.

'Megger' is a good name, and I had no idea there was such a device to measure current on a conductor alongside it's neutral or counter current carrying conductor.

Personally I'd be tempted to check it's accuracy against a traditional amprobe.

Although you wouldn't need a fancy "line splitter" (though the 10x amplification is a nice feature)to use the amp meter you already have. If the circuits for the server's are dedicated(which they probably are not) you could just check them at the panel.
Or you could build several 'makeshift' devices installed permanently inline with each server allowing you to check current any time you'd like without ever interrupting power to the server/s.

Though I also very much like the idea of a real time readout from a device via your network.
 

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DGFVT
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You might want a little more than power monitoring if you are internet hosting company. Try this; http://www.poweradmin.com/

There is a lot software for monitoring servers out there and this is just one that I did a search and found. It will give you an ideal as to what can be done. I have one customer that I am working with to do ROI on buying energy saving Dell severs to replace their existing servers. The energy saver Dell's use 33% less energy than the ones they have now. The electric power company will actually give rebates according to how much power is saved. They have monitoring software installed that tells exactly how much power is being used by each server, which makes it easy to compute what the cost savings is going to be.
 

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Discussion Starter · #6 ·
Personally I'd be tempted to check it's accuracy against a traditional amprobe.
Absolutely going to be the first thing we're doing.
Although you wouldn't need a fancy "line splitter" (though the 10x amplification is a nice feature)to use the amp meter you already have. If the circuits for the server's are dedicated(which they probably are not) you could just check them at the panel.
Servers get plugged into an APC power strip that allows us to remotely reboot servers and monitors OVERALL current. So no other way to check servers' current usage individually.
Or you could build several 'makeshift' devices installed permanently inline with each server allowing you to check current any time you'd like without ever interrupting power to the server/s.
I'd love to build something like this, but it would have to be UNBELIEVABLY reliable and very inexpensive.
Though I also very much like the idea of a real time readout from a device via your network.
yes this is the IDEAL situation. We could poll it every 5 minutes like we do for bandwidth.
 

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Discussion Starter · #7 ·
You might want a little more than power monitoring if you are internet hosting company. Try this; http://www.poweradmin.com/

There is a lot software for monitoring servers out there and this is just one that I did a search and found. It will give you an ideal as to what can be done. I have one customer that I am working with to do ROI on buying energy saving Dell severs to replace their existing servers. The energy saver Dell's use 33% less energy than the ones they have now. The electric power company will actually give rebates according to how much power is saved. They have monitoring software installed that tells exactly how much power is being used by each server, which makes it easy to compute what the cost savings is going to be.
I'm a little confused. Power Admin just seems like a regular server monitor. We have plenty of tools like this. I don't see anything about it being able to monitor power or current usage.
 

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Monitoring power to bill your customers is probably a key essential in your business, so perhaps a high end monitoring system is in order for accuracy and ease of use.

The 'makeshift' the I spoke of is not 100% legal, but as long as it's not getting "walked on"(like behind a server) it is safe.
It would simply cosist of 6" of ground and neutral wire, and 12" of hot wire all connected at one end to a male receptacle(to plug in the wall) and a female end (to plug in the server).
The longer hot wire would be 'neatly' looped next tp the others so that you could 'clamp' your amp meter around it whenever need be.

This is a cheap solution(perhaps 10 bucks per server), though would require a bit of manual surveillance. And I'll also point out that running line voltage conductors like I explained is not legal!
 

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DGFVT
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If you are interested here is a plan to build or have built a system to record/monitor the amperage of individual electrical circuits. There would be three components. The first one would be a current transformer. The CT (current transformer)could have an input rating of 0-20 amps with an output rating of 0-5 amps. The second component would be an analog to digital converter would take the 0-5 amp analog signal and convert it to a digital signal. The digital signal could be a RS485, RS232, TCP/IP Ethernet or some other digital transmission protocol. The third component would be a PC data collection/dataloging software program that would read and store the collected data.

 

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DGFVT
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Here is a cut sheet of a current transformer from Simpson. This CT just so happens to convert to a 0-10 volt signal that still can be attached to an analog to digital signal converter. The costs for just material would be in the range of $200 to $300 per measured point. So if you want to measure or record 20 points it would be $4,000 to $6,000 for the CTs and the analog to digital converters. The total installed price would depend on the installation site.
Just for you general information temperature and humidity can also be done this way.

http://www.tequipment.net/pdf/Simpson/186_accessories.pdf
 
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