relays failing??

I'm sure I'm doing something wrong, but don't have a clue.
Wired up 6 relays (elk 912) for 6 zones for irrigation system. Rules work fine to fire relays sequentially but on the 2nd run, 2 zones did not work. I checked the wiring on the relays. They were receiving voltage out from the elk but were not switching. I pulled out the active output's + 12v line and touched it to the + contacts of the other relays (all negatives tied together) and the other 4 switched audibly, but these two made no sound.
I then replaced those 2 relays last night and ran the irrigation task and all worked fine. It ran again while I was at the house tonight and the first 5 zones worked fine and the 6th did not (different relay from the 2 I replaced last night). I checked it out with that output on and all the other relays clicked on with the + wire from that output. I then looked at the (?bad?) relays I pulled out last night and they clicked on fine with 12v tonight??
Wired as follows: + 12v output from elk output on output expander to + of relay
neg output from that output expander to negatives of all relays
one 24v AC tied to all relays COM
wire to each irrigation valve to relays N/O
other half to 24v to common of valves

I am using the ELK 24 volt supply (40 VA) {I don't know what VA means-- the relay is rated for 7 amps at 30 volts}
The relay has a diode protection across the relay coil (? a type of fuse? am I overloading it somehow?)
Voltage from the elk reads 11.6 with the wires not on the relay, but reading through the contacts -/+ of active relay reads 7.4 volts (relay specs say minimum 9 volt pull in voltage -- is this the problem??)
Any help would be greatly appreciated by me, my WAF, and my newly laid sod.
Thanks
David
edited to fix the DC/AC problem

Irrigation valves are 24vac, not 24vdc. Is the transformer providing ac or dc?

Good luck,
Tim

Mr.Tim said:

Irrigation valves are 24vac, not 24vdc. Is the transformer providing ac or dc?

Good luck,
Tim

Click to expand...

oops, typo, transformer is 24 volts AC
David

Can you provide a schematic? I get lost with word descriptions when associating them with how something is wired up.

Look at my schematic HERE and see if it is wired similar to it.

Remember the diodes are polarity sensitive. My first gut feel tells me you are wiring them backwards (output will sink right to ground).

The "bar" on the diode should go to the positive end, but for getting this working correctly first, maybe just eliminate the diodes for now..

Also, insure that you are only turning on one relay at a time (in case your 24 VAC power source is drawing down from trying to power multiple valves).

EDIT: I looked at the Elk 912 Relay page and from the picture I noticed a diode is already in place. Not sure what you are doing with external diodes, but I would just not use them as they are not needed. Do make sure though that the polarity is correct going into the relay though.

BSR, thanks for the reply. Yes mine are wired remarkably like yours (thanks for the how-to). below is schematic for 3 valves, (other 3 wired the same). I have the output from the elk to the positive of the relay and negative from the output expander to the neg of the relay. All the outputs from the elk are running though a Cat 5 cable to the site of the relays in the garage.
Pardon my electronic ignorance, but am I correct in assumming the polarity of the AC doesn't matter?
Do the voltages look right? What does 40 VA on the transformer mean?
Thanks
David

wired-up said:

What does 40 VA on the transformer mean?

Click to expand...

VA = VoltAmps which is equal to Watts when the power factor equals 1.
So your 40 VA power supply can supply 40/24 = 1.6667 amps. This is more than enough to power all those relays at once.
But I suspect you are right about the voltage being an issue. What is the size and length of the wire between the relays and the output expander?

This 24 VAC wall wart is used exclusively for the valves correct? In other words, you have nothing else connected to it other than those sprinkler valves.

Using Cat5e for the run between the relay and the Elk outputs should be OK as the relay coil only draws 35 ma.

Couple of things you can do. I would first make sure that nothing is wrong with your Cat5e cable. Do you have a multimeter? If so separate the ends of the individual wires on both ends (so they are not touching each other) and on one end of the cable, place the multimeter in ohms (and largest scale if not autoscaling) and measure one wire against another with the leads. Make sure you don't touch the leads with your fingers as this can influence the reading. You want to make sure you have "infinite" resistance on all possible wire combinations. This checks for "leakage" and insures the wires are not touching each other anywhere along the cable run.

Then, using one wire as a common, clip that common wire with another one at one end of the cable. On the other end measure between those two wires with the meter on the smallest scale of ohms. You should probably be reading somewhere around three or so ohms. Do this for all the wires. This checks for "continuity" and instures there are no "breaks" in the cable run.

Make sure all the wires are properly seated in the terminals. Sometimes you can get a wire "underneath" the terminals clamps.

On the contact side of the relay, you can take a jumper wire and touch between the NO and COM connections and see if the valve comes on (for heavens sake make sure you don't touch the + or - of the coil side when you do this). This will simulate the relay turning on and at least insure that this part of the wiring is correct.

Remember that you will hear the solenoid of the valve "click" but it will take a few seconds before water will start to flow through the valve.

That's all I can think of for now.

WayneW said:

wired-up said:

What does 40 VA on the transformer mean?

Click to expand...

VA = VoltAmps which is equal to Watts when the power factor equals 1.
So your 40 VA power supply can supply 40/24 = 1.6667 amps. This is more than enough to power all those relays at once.
But I suspect you are right about the voltage being an issue. What is the size and length of the wire between the relays and the output expander?

Click to expand...

Thanks Wayne, for the explanation. The relay is rated for 10 amps at 125 volts AC on the contacts so I guess this is ok.
I have standard Category 5e carrying the 12 volt (one negative and 7 separate positives) approx 30 feet between the panel and the relays. I think Cat 5e is 24 gauge.
Voltage from the elk reads 11.6 with the wires not on the relay, but reading through the contacts -/+ of active relay reads 7.4 volts (relay specs say minimum 9 volt pull in voltage -- is this the problem??) I did however, pull the 12 volt positive from the non-working relay and touched it to the positive terminal on all the relays individually and they all had the audible click except this one.
This expander is on it's own elk power supply with battery backup, and only has 3 motions in addition to the relays.

BSR, thanks, we posted at the same time, I headed out to the house and will try your suggestions and let you know. Yes the 24 volt is only for the valves.

Thanks all, I really owe this forum a lot, and I hope to be able to someday.
David

hmmm, I guess I'm really confused now as to how you are exactly wiring all of this up. Your using an output expander and not coming off the Elk's outputs directly (from the main M1 module)?

I'm not familiar with the output expander, do you have a part number?

Wayne might be right if your running the 12 volts all over the place for other items. I'm concerned about the common reference as well. I thought you were running the - of the relay to the Elk output's negative connection (black wire on connector J-16).

Here is what is wrong on the relay trigger: There is a protection resistor in line with the M1 J16 outputs. The voltage drop across the resistor is causing the relay to not pull in. The M1RB has a driver transistor to amplify the signal from the M1 so that there is very little voltage drop.

I suggest using the M1RB or the ELK924 or a relay with a transistor driver built in. There is probably nothing wrong with the 912 relays. They just need more trip voltage than you are providing.

Spanky said:

Here is what is wrong on the relay trigger: There is a protection resistor in line with the M1 J16 outputs. The voltage drop across the resistor is causing the relay to not pull in. The M1RB has a driver transistor to amplify the signal from the M1 so that there is very little voltage drop.

I suggest using the M1RB or the ELK924 or a relay with a transistor driver built in. There is probably nothing wrong with the 912 relays. They just need more trip voltage than you are providing.

Click to expand...

OY!

This is very embarrassing as I've been recommending using the ELK-912 Relays with the Elk's M1 Outputs.

Look at the Elk M1 Manual's description of its output specifications (screen shot below).

Programmable outputs are +12 V switched positive general purpose outputs rated at 50 mA.

Click to expand...

The Elk-912 relay specifications state that it requires only 9 volts pull-in voltage at 30mA!!!

Did I somehow misread the manual/specifications? If I didn't this is causing me some angst because, as I stated above, I recommended using this relay with the Elk's outputs in a variety of posts/replies on this forum! :blink:

I am also now confused (even more).
Spanky, are you saying that the inline resistor is on the M1 board or in the 912 relay? I am measuring almost 12 volts at the distal end of the cat 5 line at the relays. But as above, I measure 7.4 volts across the - and + of the relay when it is getting voltage from M1, whether it is activated or not. If the resistor is in the relay, I guess that would make sense, but (in my electrically challenged brain) then I don't understand the specifications on the 912 instructions.
Would this cause them to fire intermittently?
If I have to go buy a M1RB, then I will. (I have to make this irrigation system work). I had chosen the 12 pack 912 because they were recommended and I didn't need 8 relays at one location and I needed some relays elsewhere.
David
Edit: one more question. I see the M1rb plugs in with a 12 conductor ribbon cable. I couldn't use this in the garage as I only have a single cat 5e running from the M1 to the garage for sprinklers. I guess I would have to get a ELK-M1XOVR - 16 Output Expander, 8 Voltage/8 Relays and connect the cat 5 into the database hub. I guess that would work (??) but now I've gone from an extra $57 (+ shipping) extra to $107 (+ shipping). ouch!

I've also purchased several of the 912 relays for upcoming projects. All of which I planned on controlling via the low current ouputs on the M1. I'm not an EE, but if the manual states it can drive a 12v load at 50ma, and the relay says it requires 12v @ 30ma, seems like it should work.

Brian

wired-up said:

Edit: one more question. I see the M1rb plugs in with a 12 conductor ribbon cable. I couldn't use this in the garage as I only have a single cat 5e running from the M1 to the garage for sprinklers. I guess I would have to get a ELK-M1XOVR - 16 Output Expander, 8 Voltage/8 Relays and connect the cat 5 into the database hub. I guess that would work (??) but now I've gone from an extra $57 (+ shipping) extra to $107 (+ shipping). ouch!

Click to expand...

Before I spent that kind of money I would personally look into a WGL Designs solution as they were specifically made to automate 24 VAC operated sprinkler valves.

brotsten said:

I've also purchased several of the 912 relays for upcoming projects. All of which I planned on controlling via the low current ouputs on the M1. I'm not an EE, but if the manual states it can drive a 12v load at 50ma, and the relay says it requires 12v @ 30ma, seems like it should work.

Brian

Click to expand...

I'm using 912 relays for controlling 2 gas fireplaces and a thermostat (big kludge, changes the resistance the thermostat sees from 10k ohms, 78 degress, to 6k ohms, 58 degrees, to kick on a heater based on the KP1 temperature, because I'm too cheap / lazy to figure out what's broken and fix it.) and have never had a problem with the relays not working.