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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => AC Power and Grounding => Topic started by: Bob Leonard on June 18, 2016, 08:46:09 am

Title: Circuit redundency
Post by: Bob Leonard on June 18, 2016, 08:46:09 am
The other day while working in a very large data center installing some routers I noticed that one company had installed a little gadget on their AC lines. A closer look and what I found was a device I was not familiar with, but was immediately interested in.

The device is manufactured by Zonit, those guys that make all the great locking cables for AC, and it was the smallest AC transfer switch I had ever seen. The data centers I work in are huge, generally a city block in size, and are fully protected against everything but an atomic blast. AC, DC, lighting, data, everything on a redundant path. So, my mind asked why use these small transfer switches at all. That was until I looked past the switch.

In my daytime world every rack will have multiple 30 - 50 amp circuits powering it, however, every device, especially smaller devices, will not have multiple redundant power supplies. Losing the power supply in the device will obviously result in that device going down, but, how many times is the circuit lost resulting in device failure?

I spoke with the guys using the devices and was told they work perfectly, there have been no failures, and they appear to be built like a brick shit house. My immediate reaction was that I should buy some for all of those devices I own that don't have dual power supplies, starting with my mixer, sound modules, and DSP.

I can picture a lot of uses for these puppies, and they're made by the same company that make those incredible locking cable, and the zDPS.

μATSTM Operational LED Indicators

The μATSTM has five LED indicators: green, blue, orange, yellow and red. It also
has an audible alarm. They are used as follows to indicate the operational
state of the μATSTM:

Green LED lit: The μATSTM is operating normally and drawing power from the
A power source.

Orange LED lit: The μATSTM is detecting an over-voltage condition on the
A power source and has disconnected from that source. It is drawing on
the B power source (where over-voltage is not monitored). The μATSTM will
continue to monitor the voltage on the A source and switch back to the A
source once the over-voltage condition is corrected.

Red LED lit: The μATSTM has had its 8A capacity limit exceeded and
activated the Virtual Circuit Breaker, disconnecting from both power
sources. An audible alarm will be generated. To reset the μATSTM after
correcting the overload condition the reset button on the rear of the unit
must be pressed or the A power source must be shut off and restored

Yellow LED lit: The μATSTM is operating normally, however the current draw
is approaching 8A. The user should review if current draws will exceed 8A in
cold start scenarios, which could trip the Virtual Circuit Breaker.
Blue LED lit: The μATSTM is operating normally and drawing power from the
B power source. The primary source is offl ine and not available or in an
under-voltage or over-voltage condition.

No LEDs lit: The μATSTM is not receiving power from the A or B sources, has
experienced an overload while on the B side with the A side unavailable, or
it has blown its internal protective overload fuses. If the fuses are blown,
the unit must be returned to Zonit for service. To determine if the unit has
overloaded while on the B side when the A side was unavailable, plug the A
side input plug into a known good power source and the unit will reset if it
is working properly.

Important Note: The μATSTM continues to connect the A source to the C13
outlet, even if the internal circuit board fails, which could result in no LEDs
being lit. The automatic transfer switch function will not work, but the unit
will continue to pass power from the A source to the C13 outlet.

Title: Re: Circuit redundency
Post by: Scott Carneval on June 18, 2016, 09:16:46 am
Correct me if I'm wrong but that looks like an IEC plug, meaning the actual power supply is internal. This device would really only give you redundancy in which 15a circuit you're drawing mains voltage from. I suppose it still may be useful for some devices with a high current draw, but for mixers and DSP I think a normal UPS would be more practical.

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Title: Re: Circuit redundency
Post by: Frank Koenig on June 18, 2016, 11:49:47 am
That looks like a really useful component for various home-brew UPS schemes. They give the change-over time as 9 - 11 ms, which is less than one cycle of the 60 Hz power. Most (all?) devices shouldn't even notice. I did something similar once using a relay (held in by A power, switches load to B power when it lets go) but it was too slow to prevent some devices from restarting. The relay consumed some 10s of Watts full-time to hold in, also not good. Thanks for posting this. Best, --Frank
Title: Re: Circuit redundency
Post by: Bob Leonard on June 19, 2016, 06:15:08 am
There seems to be some confusion.

This device is not a power supply, or is it a form of UPS. To be specific, the common consumer level UPS is not designed to be a long term source of power, or is a UPS used as a second source.

A UPS stands between your equipment and the source providing power in the event of a power failure. The UPS has a specific run time, and based on design will hold up your hardware long enough so that the hardware and associated OS may be gracefully shut down. In most cases this can be done with a serial/sense cable attached to the host or hardware being protected from power loss.

The device above is not a power supply, or is it a UPS. It could supplement a UPS if placed before it, but the sole purpose of the device is to allow a second power source to be attached to your electrical device, allowing you to have an active primary and secondary power source attached to the electrical device at the same time.

This device would be an outstanding accessory to any board or external device that does not have, or can not be outfitted with dual power supplies.

The switch does not transform your hardware. The switch provides you with the capability to run a second source of power, from a separate circuit, to your hardware, which will take over in the event power from the primary circuit is lost. The manufactures claim is up to 11amps, 8 amps recommended.

Of course this won't help with power amplifiers, but I can't think of a time when I haven't had more than two (2) sources of power running to my racks, or can I think of many mid to entry level boards or outboard hardware that draws more than 8 amps.

So, for hardware with a single power supply, or before a UPS or surge protector, this could be a solution for many.
Title: Re: Circuit redundency
Post by: Lyle Williams on June 19, 2016, 04:38:53 pm
Very cool little device.  I'm not sure I have a use for this in sound, but I certainly have a use elsewhere.
Title: Re: Circuit redundency
Post by: David Buckley on June 19, 2016, 06:29:48 pm
Over the years, I have had a truckload of bad experiences with static switches.  The only company that makes static switches that work (ie you can bet the farm on them) that I know of is Cyberex, now bought and rebundled several times over, and unfortunately their only "small" scale product (20A) was discontinued years ago, they only do big boys switches now.
Title: Re: Circuit redundency
Post by: Bill Harvey on June 21, 2016, 09:40:31 pm
I run a data center and we have a couple dozen or so transfer switches scattered throughout that provide some of the older network switch stacks with redundant power sources. Ours are made by APC and are rack-mountable. We like them because their exact operating voltage and sensitivity can be set by the user. Note that they are automatic transfer switches (ATSes) rather than static transfer switches (STSes). ATSes use relays (although very, very fast ones) and STSes would use solid-state components. STS transfers are in the single-digit ms range which works for almost anything, but they're more expensive. ATSes transfer in the (typically) 20-30ms range, but still work for almost everything and they're a lot less expensive. ATSes can, however, suffer from relay contact welding if you don't pay attention to the rated load limits.