Help with intellimeter A277 demand meter in AX
I have several Intellimeter A-277 electrical meters that I must connect to a FX60.
I have these pulse inputs tied into a PCG1711 controller and setup as accumulators. I have inferred that the correct terminals are K and Y for form A contact. The instructions say the output is 1 kilowatt hour per transition. I then brought this into a sliding window demand block. I created a calendar which resets this block monthly.
My problem is with the instructions and the formula they give... I'm not sure I'm scaled correctly and have no idea why they provide a formula and multiplier if they have stated that each pulse is 1 kw hour.
Am I missing something or can this accumulator just be linked directly to the sliding window demand block
Can you post the AX Logic for us to review?
Heres the logic. The data is in fault because I ran the station offline.
First thing is - your two pics are for two different meters. If, as you say, you have an A-277 meter, the first pic does not apply - it is for a model H or K meter with pulse option installed, so throw that one away.
So, concentrate on the second pic, it's the one you want.
You have to know what CT's (current transformers) are installed, so go look - I'll wait........
Ok, let's say you found 100A CT's. The first table says your A-277 with 100A CT's gives you a value of 2.4 KWH per pulse. If that's what your installation looks like you're done.
But, suppose your building has 600A service? One way to measure the larger current is to install 600:5 CT's on the busses and use them to feed the 100A CT by wrapping 10 turns of the 600A CT leads through the eye of your 100A CT. If your installation looks like that, then the second table says you have to multiply your 2.4 KWH by 12 giving a pulse value of (2.4 X 12 = ) 28.8 KWH per pulse. For different CT values just use the appropriate value(s) in the table(s).
Oops, one last thing - This meter looks like it has a KYZ contact output, many times this means one PULSE equals one TRANSITION, so, if you are only counting contact closures, you have to multiply your reading by two. Contact closes - that's 2.4 KWH, contact opens, that's another 2.4, but you are only counting the closures, not the opens, so you have to count 4.8 to account for that. From what you posted it's not clear whether this meter does that, you need to ask the manufacturer or rep whether a closure or a transition counts as one pulse.
Oh great, I thought of one more thing, do you have PT's (potential transformers)? Say your incoming voltage is 4160V (not uncommon for large industrial) - that's a line to neutral voltage of 2400V - your meter can't handle voltage that high, so they would install PT's to step the voltage down. If this the case you have another multiplier - for this example it would be 8.66 (2400/ 277).
So, if your meter has 100A CT's, and 600:5 CT's on top of that, and your service is 4160V with 2400:277 PT's installed, and one transition counts as one pulse, then your final value would be:
2.4 X 12 X 8.66 X 2 = 498.8 KWH per contact closure (which is what you're counting)............... Whew!
Clear as mud?
Last edited by DDC_Dan; 02-23-2013 at 12:48 AM.
Thanks Dan... The factory rep sent me a link to the pulse option doc which didn't exactly apply when I asked him some questions...
Thanks for being thorough