Energy metering with hager EC 051

I know there are a few posts on this already suggesting the hager EC 051 works well as a pulse meter and would like to try this out. Looking at the specs it appears to be a transistor output (as opposed to relay contacts) but beyond this we are not sure whether it is open source / NPN or PNP.
If anybody has connected one of these in and doesn't mind sharing with us how it was wired, please do tell..
Thanks in advance

 

Hi

We couldn't find specs on the output either so went the experimental route of just connecting to a bus-coupler and seeing how it went.

Works a treat!

We have the bus-coupler input programmed as an on-off.

Cheers

Matt

 

Thanks Matty

Just to clarify then, you connected the unit directly to the bus coupler?

i.e. without any external power supply, resistors or other such bits?

Thanks for this

Regards

SBL

 

Yes just directly to the input.

It does pain me not to have addressed the "why" but, you know, once it worked it was on to putting out the next fire...

 

If the output from the EC 051 is an open collector style, not a dry contact, then you may be compromising the safety isolation, noise immunity and communication quality of the C-Bus network. If the output from the EC 051 is not isolated from mains by 3.75kV then you have an issue.

The safest path by far is to use an Aux Input unit, not a Bus Coupler.

 

Thanks guys.

The meter states 2kv of isolation.

I guess the issue is then if its gets a lightnening strike type of transient, that this could run from the meter and up the bus coupler onto C-Bus. This said such a heavy transient / lightnening strike would no doubt upset C-Bus regardless and the client would get a new C-Bus system courtesy of the insurance company, perhaps?

If the bus coupler method does work the benefit seems to be that no external power supply and current limiting circuits are required.

So the key question then is whether the noise / interefernce potential is a real problem on a small non critical C-Bus network, and whether good wiring practices and perhaps use of a balumn around the wires between the meter and the bus coupler would help reduce any potential noise.

In terms of testing it does seem to work well with the bus coupler and of course it is a lower cost solution.

Thanks for the feedback and insight on this.

regards

 

C-Bus is an SELV system and requires 3.75KV of isolation between itself and mains. If the EC 051 has only 2KV of isolation and you connect it's output directly to a Bus Coupler you are violating the electrical safety standards. The Bus Coupler provides no isolation between it's inputs and C-Bus.

That is not the key question at all. There's a lot more to worry about than just lightning strikes and electrical noise when it comes to isolation. If someone is ever injured, and the electrical installation is audited, you may have more than just a fire to put out.

Use an Aux Input unit and all these issues go away. Yes, it's a little more effort to install as you need to mount it on a bit of DIN somewhere and, depending upon what's connected, an external power source may be necessary, but it's definitely worth it.

 

Darn those pesky regulations

Thanks for clarifying this. I read from this then that the Aux input unit does have the 3.75kV of isolation between its inputs and C-Bus?

Is this also the case with the General input unit?

Cheers

 

The Aux Input and General Input unit's inputs are less than 3.75KV, although I don't remember exactly what they are. As long as the combined total isolation between mains and C-Bus is over 3.75KV, you're fine.