Power loadshedding the right way...

[chrisexv6]

IS there a right way to shed loads off the mainboard?

I have an Altronix AL600 supply. I just offloaded my 4 wire sensors (4 glassbreaks, 4 motions) onto it. 2A of the AL600 will go to my Uplink unit. The only thing left in the system will be the smokes/RRSMOD and the data bus.

Do I want to treat the AL600 just like its part of the main board? How do you plan for worst case (the external supply goes down)? Leave the smokes connected to the mainboard (since thats a life/death issue)?

How about the databus....since keypads in alarm (especially the M1KP) take up a decent amount of current? (I have a M1KP, M1KP2, XSP and a zone expander on the databus right now, all powered off the mainboard)

Maybe Im making it harder than it should be, but now that I have all the parts Im starting to wonder what the best way to split it up would be.

Thanks in advance.

-Chris

 

[tmbrown97]

A couple of basics... your load doesn't seem too crazy - you can do the tests at full alarm and check voltage draw to see if it's within specs.

If not, it's time to pull in a supervised aux supply. I agree with keeping smokes on the main board; make sure you size your aux boards to ideally outlast the main board because if the battery on an aux board dies, everything attached goes into fault.

If you're close but just a tad over, there's also a cheater's trick where you wire something like a siren, which is high-draw, to pull its current directly from the battery but switched using a relay - this way the siren won't cause a system shutdown - it'll still draw from the battery so you need to size accordingly.

 

[chrisexv6]

I checked the current draw in alarm and without the zone expander and 4-wire sensors connected I was hitting about 700mA, pretty close to the 1A limit (or 1.5A, whatever it is). Once the expander and GBs and motions are connected it would be WAY too close for comfort. On top of that I needed to feed 2A (peak) to the Uplink unit, and wanted some future expansion (possibly to power the M1EXP and a thin client off the same power supply). So I went with the 6A supervised Altronix supply.

From what you mentioned it looks like I will keep the smokes and related on the main board. The only question is if I move power to *all* items on the databus over to the Altronix unit, or if I keep one or two key items hooked up to the panel just in case.

A side reason for doing all of this is that I am curious to see if current draw is causing the issues I had with the 2WMOD2, RRSMOD, 2WTA-B combination. It kept looping into fire trouble, fire, fire trouble, etc. to the point I couldnt disarm it. I pulled the 2WMOD2 out of the loop and it worked as expected UNTIL I wired the zone expander and 4 wire sensors back in. Then it went back to looping. That makes me wonder if Im getting close enough to overcurrent during alarm that it was making funky things happen. Now that Ive offloaded the zone expander and its sensors to the Altronix, my idle current is cut in half (havent tested full alarm current yet since the family is still sleeping).

 

[Del91574]

You can shed anything off the bus to the supply, provided a couple of items are met...this is SOP for most panels, however from installing M1's, this is what I've discovered.

First, the supply needs to have 0V loss on switching to battery only. Bad things happen on the M1 family if the bus voltage sags below 12V. If you're using Altronix supplies, using Elk's low battery cutoff/switch is not an option, they don't play nice.

Second, the bus devices need to outlast the panel, otherwise when they die, all the zones on them will fault, or worse, if the voltage is sagging, you'll get multiple reboots of the bus devices, which will cause multiple falses and possibly drag down the panel's bus at the same time. 16 zones X alarm, trouble and restore of each...if monitored, that's a heck of a lot of CS activity to bounce through in short order.

Fire alarm, technically makes no difference, and some cases, even though the panel itself may be dead, having a functioning fire or other critical condition monitoring (CO, gas) isn't a bad idea. Losing burg protection, while it may stink, having local detection of hazards that tend to exist when the power is out, such as gas, CO, and fire may be far more desirable, since people tend to do silly things when there's no electricity.

As far as driving a panel, generally having headroom in alarm condition is always preferable, usually around 60-70% of max load for a non-UL certificated system is a safe rule of thumb. Just because it "can" drive that sort of load, doesn't mean it's always a good idea.