Changing original 32Amp contactors for solid state relays?

[marconi]

Your supply is 'three phase 2 wire corner grounded delta' as in the diagram above but your line voltage is 225V (ish) instead of the 480V this diagram shows.

So in your home A is L1 and C is L2 and B is the earthed phase/line/neutral N.

Single phase supplies are derived by connecting between pairs of lines A-B, A-C and B-C.

Your UFH uses all these pairings to 'spread' the loading over the three lines/phases since this is a large long duration power demand and makes best use of capacity of the three lines to your home.

I did not delve into how all your other home final circuits are wired eg: lighting and sockets but I strongly suspect they are connected A-B thus L1-N, and B-C thus L2-N so that single pole switching may be used in the line/phase only because only L1 and L2 are at 225V wrt to N and E.... and N is at a low voltage wrt to E - I think we measured 20V ish.

When L1 and L2 are used the switching must be double pole as you have gathered from the contactor contacts wiring for the UFH because both lines are at 225V wrt to N and E.

 

[Yonny24]

Hi Marconi.

I believe this is how they have wired it. 2 of the UFH zones are tiny (1m2) bathrooms so use very little. Not 100% on the middle UFH but looks like they share the same cables.

Hi again,

Revisiting this set up from upstairs. I haven't added individual contactors yet with new neutral cables splitting them up.

My question/doubt now is about the power meter I have installed.

I have the 2 inputs of the power meter fed from the CBS outputs #4 and #5. I thought this would measure only 4 of the zones.

The red led on the power meter pulses depending on the power going through it. Remains green when no power is going through it.

Now what I observed is that it measures power from all 6 zones here. The led flashes at different rates for each zone UFH tested independently.

Is this due to the way the three phase 2 wire corner grounded delta works, and is capable of measuring the power used correctly for all zones?

Thanks in advance

 

[marconi]

In order to measure the power consumed by each of the three UFH zones the power meters P need to wired in between the zones and the contactor C as I have drawn in my attached diagram.

The same holds for elsewhere in your home to monitor power consumption by each UFH zone. So you should revisit how the power meters have been wired in - I cannot do that for you because I can no longer open any attached images in previous posts.

The total power consumption of your home however is measured by two meters - you might have thought three were required. For a three phase three wire system only two meters are necessary; the total power consumption being the sum of the two readings. Blondel's theorem if you want to look it up. My second attachment shows how they are connected. Note how the two meters are both connected to the third line N/L3.

If there were three meters they would be connected as in the last drawing, one in each line and the meters then connected to a common star node. Simply by making one of the lines common to the power meters one of the three meters becomes superfluous and an economy can be made.

Blondel's theorem:

Blondel’s theorem | Power in Poly-Phase System | Electricalvoice - https://electricalvoice.com/blondels-theorem-power-in-poly-phase-system/

 

[Yonny24]

In order to measure the power consumed by each of the three UFH zones the power meters P need to wired in between the zones and the contactor C as I have drawn in my attached diagram.

The same holds for elsewhere in your home to monitor power consumption by each UFH zone. So you should revisit how the power meters have been wired in - I cannot do that for you because I can no longer open any attached images in previous posts.

The total power consumption of your home however is measured by two meters - you might have thought three were required. For a three phase three wire system only two meters are necessary; the total power consumption being the sum of the two readings. Blondel's theorem if you want to look it up. My second attachment shows how they are connected. Note how the two meters are both connected to the third line N/L3.

If there were three meters they would be connected as in the last drawing, one in each line and the meters then connected to a common star node. Simply by making one of the lines common to the power meters one of the three meters becomes superfluous and an economy can be made.

Blondel's theorem:

Blondel’s theorem | Power in Poly-Phase System | Electricalvoice - https://electricalvoice.com/blondels-theorem-power-in-poly-phase-system/

Many thanks Marconi.

I do have one doubt - the current set up I have to read the power seems to register power going through UFH 1 and 2 as labelled also which surprised me. I thought it would have only read power on the other lines to the UFH. In fact, it registers power for each UFH if turned on individually.

Is it giving me false readings set up this way?

Appears to read about 1.1 Kwh for the large UFH 1 and 0.2 Kwh for 2 (small bathroom 1.5m2) which I expected but as mentioned I would not have expected it to read any power for these 2 the way it is connected.
Rather confused.

Regards
[automerge]1595421683[/automerge]
Just going to double check my drawing later - see if I have identified the connections from and to the PM correctly.

 

[Yonny24]

If I do need the 2 power meters to measure accurately the 3 phase upstairs following the 3rd setup would this be the correct way to wire them up?

Still curious why my current one PM set up connected to just the L2 and N/L3 is measuring power for all 6 UFH zones.

Thanks

 

[marconi]

If you want to measure total power provided by the 3 phase 3 wire supply to all the UFH connected to a panel then use two meters as I showed in my second diagram ie: place the two meters between the main switch and the contactors. The input to one meter is L1-N and to the other L2-N.

If you want to measure the power consumed by an individual UFH zone (effectively a single phase circuit) then use my first diagram ie: place the PM between the output of the contactor and the UFH zone. The input will be one of these pairs L1-N, L2-N or L1-L2.

Be careful to use the correct terminals on the PM ie: Lin, Lout, Nin and Nout (though it is most likely Nin and Nout are the same node so it is immaterial which is in and which is out.

I cannot turn up the spec for the DM25S - do you have it?

If you wish we can arrange a zoom session if that would be easier for you.

Regards

Marconi

 

[Yonny24]

Sorry just posted and saw your post above as I'm reading through it now.

Perfect many thanks again.

I'll go for set up #2. 2 power meters between the CBS and contactor. Just need the total for all.
So my figures for the UFH#1/#2 are incorrect as I do not have L2 connected even though the PM shows some power feeding through it, possibly just a % of the total power. Did suspect the street side new meter was reading more KwH than I calculated when running the UFH upstairs. Downstairs is pretty much spot on.

Will purchase another PM.
[automerge]1595451726[/automerge]
I have found these specs (mine is the 40 amp version).

Model Number:
DM25S
Display Type:
Digital Only
Phase:
Single Phase
Measuring Energy Range:
0-99999
Accuracy Class:
Class1
Output Voltage:
220VAC,110VAC
Operating Temperature:
-25℃~+55℃
Dimensions:
DIN EN50022 Standard
Product Name:
Meter Energy
Width:
18mm (One Module)
Current Specification (A):
5(20),5(30)A,5(40)A
Frequency:
50-60HZ
Constant:
2000imp/kWh
Display Mode:
5+1 Digits Counter Display
Connection Mode:
Direct Mode
Standard:
IEC60253-21

 

[Yonny24]

Sorry just posted and saw your post above as I'm reading through it now.

Perfect many thanks again.

I'll go for set up #2. 2 power meters between the CBS and contactor. Just need the total for all.
So my figures for the UFH#1/#2 are incorrect as I do not have L2 connected even though the PM shows some power feeding through it, possibly just a % of the total power. Did suspect the street side new meter was reading more KwH than I calculated when running the UFH upstairs. Downstairs is pretty much spot on.

Will purchase another PM.
[automerge]1595451726[/automerge]
I have found these specs (mine is the 40 amp version).

Model Number:
DM25S
Display Type:
Digital Only
Phase:
Single Phase
Measuring Energy Range:
0-99999
Accuracy Class:
Class1
Output Voltage:
220VAC,110VAC
Operating Temperature:
-25℃~+55℃
Dimensions:
DIN EN50022 Standard
Product Name:
Meter Energy
Width:
18mm (One Module)
Current Specification (A):
5(20),5(30)A,5(40)A
Frequency:
50-60HZ
Constant:
2000imp/kWh
Display Mode:
5+1 Digits Counter Display
Connection Mode:
Direct Mode
Standard:
IEC60253-21

My previous drawing of the power meter was incorrect. The middle output of the CBS is the N feeding to the middle 2 inputs of the contactor.
I have swapped the power meter over to the other live and neutral to measure ufh 1 and 2 for now.

 

[Yonny24]

I suspected measuring the UFH #1 and #2 with the PM wired connected to L1 and N (as opposed to L2 and N) the Kwh is double than previously measured.

 

[Yonny24]

Left hand drawing is the proposed wiring for the 2 x PM's. With the N line going in and out of both power meters. is this correct according to your diagram? Right is original wiring.

Thanks

 

[marconi]

Yours will work but it is simpler to do it like my attached diagram. Add the wire I have indicated in blue to go to the link between the middle terminals of the CTR and remove the two I have indicated in white.

(A power meter needs to know the voltage which it obtains from the two inputs and the current flow between the line input and line output. This why we can dispense with the white wires.)

 

[Yonny24]

Yours will work but it is simpler to do it like my attached diagram. Add the wire I have indicated in blue to go to the link between the middle terminals of the CTR and remove the two I have indicated in white.

(A power meter needs to know the voltage which it obtains from the two inputs and the current flow between the line input and line output. This why we can dispense with the white wires.)

Many thanks Marconi.

I think I will do the same with the downstairs wiring. 2 x powermeters between the main CBS and contactors (currently have 3 after the 3 contactors). I really only need to measure the total going through the 3 phase wiring now. This way I can re-use one of the 3 PM's I have and install it upstairs. So I'll have 2 downstairs and 2 upstairs. Makes the wiring a bit neater also.

Have a good weekend

 

[Yonny24]

Many thanks Marconi.

I think I will do the same with the downstairs wiring. 2 x powermeters between the main CBS and contactors (currently have 3 after the 3 contactors). I really only need to measure the total going through the 3 phase wiring now. This way I can re-use one of the 3 PM's I have and install it upstairs. So I'll have 2 downstairs and 2 upstairs. Makes the wiring a bit neater also.

Have a good weekend

All completed this weekend. 2 power meters installed between the CBS and contactors downstairs and 2 upstairs. Working Perfectly.

Thank you very much Marconi!