Hi all, this question regards measuring of high ac power (several hundreds of amps on 3x230 V grid, therefore hundreds of kVA) in much smaller Victron system. So far I have always installed Victron systems where grid measuring could be done either by Multis/Quattros themselves, or by one of the supported energy meters. Recently one of my clients came up with a project, where it would be desirable to use relatively small Victron system (3x5000VA multi-II) which would be used only as a backup for critical loads of one building, with relatively large ac coupled Fronius system (around 50 kWp on the INPUT of multis). However, the whole building has around 300A main circuit braker and therefore to successfully setup an ESS with a grid meter, I would need energy meter that can measure several hundreds of amps and comunicates with Cerbo. Could anyone give me a clue how to do this? The best option would be to use Victron energy meter VM-3P75CT (cince it should have the fastest measuring time and is made for victron), but it has only a range of 80A and I couldnt find if or how it is possible to use different current transformers which would allow larger current range. Thank you in advance for all your advises.
I use Carlo Gavazzi EM530 Energy meters with external 5A CTs for grid metering,
These are recognized by VenusOS and have a fast update rate like the Victron meter.
The EM540 is nearly identical but has internal CTs, but those are not large enough.
There are several different models, but only the EM530DINAV53XS1X is supported, RS-485 only. These are rather expensive.
I use CTs with a 40:1 ratio, meaning 200A is the maximum current.
Luckily, these were available on Amazon and were inexpensive (nodehawk brand).
You would need 5A CTs with a 60:1 ratio to measure up to 300A.
Finding suitable CTs may be challenging depending on your location.
We use ABB counters for our 250kVA transformer. The RS485 terminals A und B have diffrent definition for plus and minus or inverted and non inverted signals but worked out of the box with Venus-OS.
Be warned: ABB sells many many models silver/gold and others with more or less features direct or with CT of any size. As calibration expires within 7 years, there is no dealer what has everything on stock. Simply order the model of your choice with CT of your choice and it will be supplied 2-3 weeks later.
Thank you very much for your tips guys! I really appreciate it.
You are welcome.
I just noticed that is document has been updated:
SCT-T24 is a good pairing with this meter for the OP’s requirement.
Hello @ricardocello ,
I just posted a question that you may have an answer to. My customer wants to be alerted when grid voltage and frequency deviate more than +/-5% of 480V or +/-2% of 60Hz. On VRM via the alarm notification options. Possible? Probably, and ChatGPT thinks it is. But would love to hear from experience that it works before I spend $500 or so (meter is about $350 and one of the 3 CT’s I need is about $150). Thanks!
Looks like that EM330 grid meter will do up to 480V L-L and 277 L-N nominal 3-phase, so that is good.
It has a max overload voltage of 1.2Un, which would be 576V, so no problem there either.
Is this configuration using three of those new Victron 277V inverters in 3-phase?
I have not done what you are asking for, but if I were to do it:
I would go to Settings, Set Alarm Rules >, Add New Alarm Rule button. The 60 second delay in notification might be a dealbreaker for your customer.
Note that you will need voltage rules for each phase independently.
And frequency checks as well.
I’ll try it for 120V and see what happens.
Super helpful! You’ve shown me that it should work. I won’t hold you to that, but it gives me enough confidence to go ahead and get a sample set ordered.
I’ll have to play with it to see if that 60 second “notify after” is problematic or not. They don’t necesarrily need to be alerted at the moment of the grid power being out of range, but I do want them to be notified eventually that there was a second in which it was out of range (refresh rate on EM330 is 0.75 seconds) .
Being out of range, may damage their sensitive equipment. They’re not hoping to prevent damage (yet), but simply wanting to know why damage may have occurred so they have evidence to charge their customer for the repair costs if their power supply lead to the issue.
Maybe I can ensure an alert will happen by setting the “clear low alarm above…” value significantly above the alarm threshold. So, alarm at 456V (5% below 480 nominal) but don’t clear till maybe 475V. Hard to say if that will work. I do wish the 60 second thing could be adjusted to whatever I want. They can always use an email account separate from their own, in order to not mind getting bombarded by nuisance alarms.
Thanks for doing that test for me, and providing those amazingly helpful screenshots!!!
Plus, I suppose I could even set the “clear low alarm above…” setpoint to some crazy high value (say 520V even), that will never clear even if conditions return to normal.
This would be OK, as long as a VRM user who gets the alert could go into VRM and manually Clear the Alarm. The alarm would not come back even though we haven’t hit the clear set-point, if the grid power has returned to the acceptable range. I’ll test that when I get either my Victron branded Meter in (I’ve ordered one, to be ready for other applications) or the actual Carlo Gavazzi one in (that I haven’t yet ordered).
Yes, I got an alarm from my 121V cutoff test (I got impatient and lowered the high value for testing).
