GCN LAB REVIEWS

Double the power source, reliability with automatic transfer switch

The product of the month for July is the Zonit Structured Solutions uATS Micro Automatic Transfer Switch. Because the July issue is all about computers and processors, we thought it would be nice to highlight a product that supports them.

The uATS switch looks like a weird power plug. There is a central block that pushes into the power intake on almost any server or desktop. Then there are two distinct cords that come off of it. One is labeled A for the primary source of power, and one is labeled B to be used as backup. The switch creates a redundant power supply for devices that do not have one already. Although it’s a little expensive at $319 for a single unit, or $7,560 for a 25 pack — which comes down to $302.40 per unit — setting up a system with a redundant power supply this way is a lot cheaper than having one built like that.


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Ideally, you would plug the A source into one circuit and the B source into another. It does little good to have them both coming off the same power stream because B is your backup if A fails. Taken just as a splitter of power, this is a nice way to set up redundant power sources. You could even unplug one of the sources and hook it up to an extension cord to move the unit without having to power it down first.

But the switch from Zonit is more than just a dummy two-way plug with no intelligence. There is a surprising amount of power regulation that goes on inside. For example, if source A suddenly experiences a low stream of power, the plug will pull power from the B source in less than one power cycle to compensate, so no disruption is passed on to the valuable equipment it’s protecting. If the A source experiences a voltage overload or surge, it is cut off all together and the B source is used instead.

The plug is designed to always use the A source if power is available for it and of acceptable quality. That way, data center managers can plan their power management for each device, a real need at large facilities. Most of the time, if disrupted A source power is acceptable for six seconds, the B source will be ignored and the A source brought back into the device the plug is protecting.

Surprisingly, the plug does a good job of displaying what is going on. There are a row of LED lights along the back side, which sticks out from a protected device. A color-coded chart shows the various power conditions. Most of the time they will probably illuminate green, which indicates that power is coming from the A source with no problems. If the light is blue, it means that A is being ignored because of some problem — perhaps you unplugged it for a hot move — and B is being used instead but without any problems. There are other colors for different conditions, and a code on the side of the plug tells you what is what. The plug can even buzz if something really bad is going on, which might surprise you the first time it happens.

As a little bonus, the plug comes with metal tabs and plastic ties that can be used to lock it against a server it’s protecting. That won’t prevent someone from unplugging the two cords at the other end, but it will stop them from pulling it directly out from the server. With the security in place, the switch makes it so your redundant power supply truly is protected as a part of your overall power system.

Any device that can add a needed feature to a computer or server for less than the cost of putting it in originally is worthy of praise. And the Zonit Structured Solutions uATS Micro Automatic Transfer Switch fits that bill. Although skeptical at first, after extensive testing, we’ve decided to add them into the lab test bed to protect experiments in which the loss of power would mean the loss of a lot of test data.

Zonit Structured Solutions, www.zonit.com

Reader Comments

Sat, Oct 1, 2011 Dan

Your comment, taken as is, is true. However, in context, referencing the previous sentence, "One is labeled A for the primary source of power, and one is labeled B to be used as backup", means a back-up power source is required. Thus, the transfer switch, semantics aside, does provide a simple means to provide a 'power supply' should a back-up power supply exist to begin with. I am sure, since others have not taken your position and blogged in, that most understand the concept.

Tue, Jul 26, 2011 Mike

You state that it "creates a redundant power supply" for devices that don't ship with one. This is not true. It is not a PSU, nor does it help in the advent of a failure in a primary PSU. "A power supply" for computers is not the same as the supply of mains power.

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