Reading dimmer channel currents

I have a number of Professional and Architectural dimmers on site.

I know Toolkit can tell me what current is being drawn on each output channel; my question is how can I get at this information at a programming level?

I expected to find it as a status variable the same way I already retrieve NetVoltage but it doesn't seem to be there :-(

 

The output current is not available from logic or via System IO Variables.

 

That'll be a "no" then..

Is there a technical reason why this isn't available? As the data is available via C-Gate to Toolkit it seems like something that could be added to C-Gate if there was the demand for it?

 

Hi More-solutions,

I know it is not exactly what you want and you may have considered this already, but you could (quite in-expensively) use some of the 5504CMU modules to monitor your channels if you really needed to know what each was doing.

You could deploy the CT before the dimmer to monitor the whole dimmers current use or on the actual dimmer channel for a particular circuit.

Regards,

Brad

 

Hi Brad,

To be honest, once we get to the point of installing CTs they'd probably just install submetering and do the job "properly". I was looking for a software option that would avoid the need to install new hardware (there are several hundred dimmers spread across this site).

Mark

 

Hi Mark,

Without knowing the application that you want the current data for and what the site is like makes it a stumble in the dark from this end. What is the purpose of needing the current in logic I guess is my main question. Are you trying to make something like an energy monitoring system for your client? or load shedding perhaps?

Without knowing the purpose, have you considered possibly using the 'Load Monitor' function in PICED, HomeGate and Schedule Plus. It approximates the wattage being drawn on each group address (which usually relates to a dimmer channel) based on the level setting and the wattage assigned to the group address. You can extrapolate 'current' from that output though it would only be ball-park. I used Load Monitor for 'energy monitoring' graphs before the 5504CMU came out.

I know its not 'real' usage data as such but may be suitable for your purpose? Whatever that purpose is?

All the best,

Brad

 

It's a large commercial building, comprising ~30 C-Bus networks connected via CNIs to a head-end PC with C-Gate (which Citect and a few other bits of custom code talk through).

In most of the areas where there is dimming control there is also local control (via C-Bus) of some kind, which means that people often turn lights on but don't turn them off again.

The desire is to obtain information about how much power is being used in these areas, particularly out of hours. Where that leads to will depend on the data it presents.

A secondary purpose would be to detect lamp failures based on current being less than expected.

I haven't considered this, as it's not something I'm familiar with. My guess is that it probably won't suit the environment (multiple networks, no bridges) but I'll go and take a look. But by the sound of it I could so something fairly similar anyway at the application level, provided I can build up a table of current usage per channel. I don't think we have this information at present (and it's a *lot* of channels to find out) but it would have the advantage of working just as well with all the relay channels (which substantially outnumber the dimmed circuits).

Real usage would be great, of-course, which is why I was looking at the information the dimmers already give to Toolkit (although that only provides instantaneous figures and any attempt to convert to kWh will introduce approximations). But anything that gives us an idea would be a good start. I'd love to sell them a few thousand 5504CMU but I don't they'll go for it - but if I can highlight areas of particular interest then maybe a selective installation would be viable.

Thanks for the suggestions.

 

Ah, I hadn't realised that it was only those dimmers. (Tell a lie: I had realised previously that the 12-ch architectural dimmers didn't show it but had forgotten. Sign of age!)

For diagnostic purposes I have to say it's been a great asset, I've used it many times to diagnose problems. The only dimmers I've had real problems with where I've needed it have been the 4-ch Pro though.

If all I am looking for is a change (ie 100% output was giving me 6A reading, now it's only giving me 4.5A) this can be done without too much tweaking and could certainly be automated, which was one of the things I was looking at doing if I had the information outside TK.

Thanks for the frank appraisal of the situation!

I'm more than happy to do the heavy lifting if it's possible to do this from my end (after all my time would be chargeable!), even if it's not "easy". I did think about setting up a test connection, and looking at level 9 logs whilst reading the levels in TK to try to reverse engineer the steps needed to read the values, for example. But I don't really want to go quite that far into "unsupported" territory. On the other hand, if someone in the know were prepared to give me a few (unsupported) hints I'd probably be able to make a case for giving it a shot.

Mark

 

Looking for a lower current reading than expected on the channel would also have to take into account the current level of the dimmer channel. A channel dimmed to ~75% would give a similar reading to a channel at 100% with 1/4 of the lights failed (ignoring temperature effects).

 

Indeed, but that's easily handled in software. The lights spend enough time at 100% that I can just look at the readings at 100%. At the end of the day it's just an indication; someone can then go and check.