A/C failure monitoring...looking for tips

[wavetar]

I'm looking to the group for advice/tips/tricks/experiences with site A/C failure monitoring. In my case, I have a customer with repeaters which are not capable of giving an over-the-air indication that A/C power has failed. 12Vdc battery backup is available at the site, and the repeater power supply is capable of giving a TTL high or low output on A/C failure. My initial thought is to use some sort of advanced timed relay which could key up a base station upon TTL signal from the power supply...perhaps one that could do so at timed intervals until the A/C is restored...if that exists. The base would be set up to give a string of DTMF or some other audible indication on the channel that something is wrong. The customer uses aliasing so I could even set it up to show 'power fail' or similar on the receiving radios.

Anyone out there use a similar set-up for A/C failure alerting? Looking specifically for makes/models of the relay or 'black box'...whatever it may be.

Over the air is preferred to a dialer to a phone/pager, although I'll look at that if need be. Thanks!

[Motoboy]

We use the Ritron Quick Talk on most of our mission-critical sites. This gives a plain language spoken message that the utility power has failed. This is a message that you record on the unit, so the voice that goes out is yours. The Ritron looks for a contact closure, so we use a 12VDC wall transformer and a relay. The 120mW transmitter is powered by AA batteries (changed yearly when PM check is performed). Program for the repeater's input frequency, and the message will be broadcast on the repeater. The unit can also be programmed to transmit when the power has been restored.

Check out: http://www.ritron.com/prod_rqt.html

/\/\b

[wavetar]

Neat box, and almost what I need...I failed to mention it's a trunked system, not conventional. I'd also like something capable of repeating the voice/tone/whatever a set number of times, or every 'x' minutes.

[firemedic]

Zetron Sentrivoice products?

http://www.zetron.com/data/site/templat ... ring/m1516

I've seen these used at a few of our tower sites and the audio fed into the backhaul circuits to the consoles or sent into the repeaters for on the air alerts.

[wavetar]

Thanks for the response. It appears it will do what I need, even the repeating alarm message. I knew about the SentriDial and SentriVoice products, but the price tag is hefty so I hadn't looked at the specs. It may very well be the answer, unless there's a lower-tier product out there which can do the same, without all the extras. Thanks again,

Todd

[com501]

Out here in Hicksville, we just wait for the customers to call. Usually the AC failed weeks ago and the generator finally ran out of fuel.

Anyone got a snocat with a 5000 gallon diesel tank to make it to the site?

[firemedic]

This would be fairly straightfoward for someone familiar with PIC development to provide a low chip count solution similar to the NHRC repeater controllers. Maybe an untapped market? Just a thought.

[Bill_G]

We're running into a similar request from a customer with a new system. They cut back the project removing the batteries and chargers electing to go with UPS's to keep the gps and signal shelves alive until the genset kicked in. They also cut out the alarm monitoring system. Now, they want some indication a site is on gen with OTA annuciation. The old fashioned beep is satisfactory .... they say. I'll have to Mcguiver something. I have some Model 18's laying around. Not terribly fond of them, Might be able to press them into service, though they are kind of overkill for the task.

[wavetar]

Thanks guys. I could design something purpose-specific that would work for less money, but I think I'm gonna go with the Sentrivoice, even though it's overkill, since it does everything I want it too. Also, that way anyone checking problems out in the future will have a manufacturer supported box to deal with, and not my own circuit to figure out!

[Bill_G]

Let us know what you do, and how well it works. Our sales mgr was pressing me for options, and I told him no one sells a low cost single purpose box that senses AC fail and keys the local station that is now dead because the AC is out. The MTR and Quantar have alarm over the air capability built in if the battery backup option is also used. But, they didn't choose those stations, and they struck batteries from the project. Rock <==> hard place

[wavetar]

Our sales mgr was pressing me for options, and I told him no one sells a low cost single purpose box that senses AC fail and keys the local station that is now dead because the AC is out.

I don't see why that wouldn't work! Lol, yeah, at least I have battery backup on the repeaters.

[desperado]

Is there ANY monitoring at the sites?

What I have seen done in the past for monitoring is a 240 volt relay across a 240 circuit (senses a single phase failure as well as a full failure)
the normally closed contacts were wired to the MOSCAD monitoring system and it's on the gen set to pass the alarm back to the monitoring NOC.

See if you figure a way to turn on a MDC1200 burst on the repeater with an unused ID that can be assigned to a "PWR FAIL" alias

[kb4mdz]

So, let me get this straight. It's important enough to spend the money to get the project up and running, but not important enough to know when it stops running, or threatens to stop running, or has an unexplained hiccup (granted, catching those is an art form in itself), or generally monitoring its health, or...

Why don't you just ask them to call you when they need to have it done over; there's never enough time or resources to do it right, but there's always time & resources to do it over, the way it was first proposed.

And my guess about the OTA beep; it will happen sooooo rarely, the people that are supposed to respond to it won't remember what it is, (because they never hear it during normal ops), (and because when they DO hear the OTA beep, the stuff is hitting the impeller, and so they're busy covering other aspects of the emergency.

Sorry for such bitterness in one so young as me.....

Oh, and two more products/ vendors:

http://www.davicom.com

and:

http://www.pagetek.net/products.html

We're running into a similar request from a customer with a new system. They cut back the project removing the batteries and chargers electing to go with UPS's to keep the gps and signal shelves alive until the genset kicked in. They also cut out the alarm monitoring system. Now, they want some indication a site is on gen with OTA annuciation. The old fashioned beep is satisfactory .... they say. I'll have to Mcguiver something. I have some Model 18's laying around. Not terribly fond of them, Might be able to press them into service, though they are kind of overkill for the task.

[Bill_G]

I'll back door something. Our contract has a four year warranty period. Being lazy at heart ... err, efficient I mean ... I'll want a better way of diagnosing a problem than reading tea leaves.

[RFguy]

I have used this in one application.It has trigger inputs and plays pre-recoreded voice messages. It has a PTT output and will run on 12VDC. It can play messages on input closure and a different mesage when the input opens (Just run a AC powered relay).

Might be a cheaper alternative to the SentriVoice.

http://www.cfsound.com/index_CFSound.asp

[wavetar]

I have used this in one application.It has trigger inputs and plays pre-recoreded voice messages. It has a PTT output and will run on 12VDC. It can play messages on input closure and a different mesage when the input opens (Just run a AC powered relay).

Might be a cheaper alternative to the SentriVoice.

http://www.cfsound.com/index_CFSound.asp

Ah, nice looking unit, and yes, much lower priced than the SentriVoice. I've already given my customer 2 quotes...one for the SentriVoice, the other for just providing a relay closure as they say they may have existing cabling available down to their control room for an alarm indicator. This gives a nice 3rd option, thanks!

Todd

[Bill_G]

We use the Ritron Quick Talk on most of our mission-critical sites. This gives a plain language spoken message that the utility power has failed. This is a message that you record on the unit, so the voice that goes out is yours. The Ritron looks for a contact closure, so we use a 12VDC wall transformer and a relay. The 120mW transmitter is powered by AA batteries (changed yearly when PM check is performed). Program for the repeater's input frequency, and the message will be broadcast on the repeater. The unit can also be programmed to transmit when the power has been restored.

Check out: http://www.ritron.com/prod_rqt.html

/\/\b

I am pushing our management to purchase four of these and get them installed on a new system that is more than an hour of windshield time away. In the last month I have responded to three "SYSTEM DOWN!!" panic calls after hours and/or weekend that were caused by site AC power failure. According to the JPS voter stats, the system averages 1 hour fifteen minutes usage per week for rural fire and EMS dispatch. So, time between activity can be long enough that no one knows a site is down until they attempt to tap out the volunteers. This Ritron looks like a good fit for this application.

[RFguy]

Maybe they should spend some $ on battery backup first.