Changing original 32Amp contactors for solid state relays?

[Yonny24]

Other side of the wall. Thick Grey cable is the supply from the overhead street cables.

 

[marconi]

It must be getting late where you are. So one last photo please looking up underneath the meters to see the individual wires going into it. Then I will leave you be until tomorrow. I am going to cook some minty lamb mince Devon pasties.


Not 'did' - meant to type disconnector or main breaker if you prefer.

Where are you in Uruguay? I am in London.

 

[Yonny24]

Sounds tasty. Miss many things from the UK.
We're 4 hours behind the UK so on my lunch break now. Work remotely here.
I live in Barra de Carrasco, Canelones. Just outside Montevideo.
Tricky to take photos as the meter is in a big sealed box with a small window just big enough to get my hand in.

Bon Appétit or buen provecho.
Regards

 

[marconi]

Good morning. I will start to produce some drawings today. First though please tell me the colours of the wires in the thick supply cable under the meter.

From the meter box it looks like 3 reds head out to your home and no other wires - is this correct? What colours do they connect to at the meter? If you cannot say then please make a drawing for me.

There is also a terminal schematic on the plastic cover over the meter terminals which I cannot see completely - could you draw or photo it and mark up where the wires of the supply and the 3 reds connect to?

 

[marconi]

Observations 1

a. If one studies Drawing 1 attached, one can observe that through the 4 pole disconnector (top left) and then the 3 white wires to above the 5 circuit breakers all the 3 white wires top left are joined together by the black busbar. This means these three white wires top left cannot be L1, L2 and N because a short circuit would have occurred rupturing a fuse or tripping a circuit breaker external to this enclosure. If a short circuit has not happened then they more likely to be of the same potential ie: a line or a neutral. The N, L1, L2 and L3 markings on the disconnector are to inform how it should be connected to such a supply if presented to it.

b. Studying further, one can readily see that each of the 2 wire digital power meters are connected across a 20A circuit breaker - this is incorrect. When the circuit breaker is closed the input to the power meter is short circuited and will not read any power consumption. In addition, the power meter requires an L and N at its input where only an L or N (yet to be confirmed) has actually been connected. I note the meters are reading zero.

c. The output side of the power meter connects to the input of a contactor by the blue and white wires and then from the output of each contactor to the floor heating elements ( I assume at this stage). Because only an L or an N (yet to be confirmed) is provided at the input to each contactor then no supply voltage will ever be connected across the elements - therefore they will not heat up. I suspect then that the underfloor heating system does not work at all at the moment.

d. The timer, albeit now redundant, still has two wires to it presumably intended as its supply - blue and white. Since these are derived wrongly from the two circuit breakers on the far right whose inputs are connected together by the black busbar there will be no voltage supply applied to the timer - it will not function.

e. From d), since the wifi switch has been tapped off the input to the timer it too has not voltage supply and will not function.

f. it would be impossible to measure with respect to earth the three voltages 230, 209 and 23V at the input terminals to the disconnector while it was closed because as mentioned when the disconnector is closed all the two sets of 3 white wires are at the same potential because of the black busbar.

It looks to me then that the wiring for the UFH was wrong from the very start or changes have been made which have resulted in a completely incorrect arrangement. Do you know the history of the UFH - did it ever work?

 

[Yonny24]

Observations 1

a. If one studies Drawing 1 attached, one can observe that through the 4 pole disconnector (top left) and then the 3 white wires to above the 5 circuit breakers all the 3 white wires top left are joined together by the black busbar. This means these three white wires top left cannot be L1, L2 and N because a short circuit would have occurred rupturing a fuse or tripping a circuit breaker external to this enclosure. If a short circuit has not happened then they more likely to be of the same potential ie: a line or a neutral. The N, L1, L2 and L3 markings on the disconnector are to inform how it should be connected to such a supply if presented to it.

b. Studying further, one can readily see that each of the 2 wire digital power meters are connected across a 20A circuit breaker - this is incorrect. When the circuit breaker is closed the input to the power meter is short circuited and will not read any power consumption. In addition, the power meter requires an L and N at its input where only an L or N (yet to be confirmed) has actually been connected. I note the meters are reading zero.

c. The output side of the power meter connects to the input of a contactor by the blue and white wires and then from the output of each contactor to the floor heating elements ( I assume at this stage). Because only an L or an N (yet to be confirmed) is provided at the input to each contactor then no supply voltage will ever be connected across the elements - therefore they will not heat up. I suspect then that the underfloor heating system does not work at all at the moment.

d. The timer, albeit now redundant, still has two wires to it presumably intended as its supply - blue and white. Since these are derived wrongly from the two circuit breakers on the far right whose inputs are connected together by the black busbar there will be no voltage supply applied to the timer - it will not function.

e. From d), since the wifi switch has been tapped off the input to the timer it too has not voltage supply and will not function.

f. it would be impossible to measure with respect to earth the three voltages 230, 209 and 23V at the input terminals to the disconnector while it was closed because as mentioned when the disconnector is closed all the two sets of 3 white wires are at the same potential because of the black busbar.

It looks to me then that the wiring for the UFH was wrong from the very start or changes have been made which have resulted in a completely incorrect arrangement. Do you know the history of the UFH - did it ever work?

Wow thanks for your detailed reply.
I'll reply to a few of the points and look into it in more detail later and get back to you.

b - The meters are working perfectly. They measure 230v across the input terminals and 230v across the outputs. They turn over and the green light flashes red when current is flowing through. The dining room was turned on last night and used 2000 kwh. Now reading 5.1 kw

c- the outputs of the meters read 230v (across the white and blue terminals) and feed the contactors. These heat up when the timer activates them. All the floor heating works.

d- the original timer on the right also has 230v across the blue and white wires. This has always worked and did switch on the contactors before I switched the timer over to the sonoff.

f- I measured the 3 voltages with respect to earth at the input of the main breaker (3 white wires).

Every contactor's input terminals has 230v across the white and blue wires and also across the output terminals when switched on (and they get hot).

Sorry to throw a spanner in the works.
I'll have a look at the external meter box later and get back to you.

Many thanks

 

[marconi]

That means then that what I see in the photos is inaccurate. Could you draw the wiring for me to study?

Could you confirm (safely) what the black bar along the 5 cbs is and does? Does it connect together all the top terminals?

Does the group of three whites under the disconnector go to above the 3 left side cbs.

 

[Yonny24]

That means then that what I see in the photos is inaccurate. Could you draw the wiring for me to study?

Could you confirm (safely) what the black bar along the 5 cbs is and does? Does it connect together all the top terminals?

Does the group of three whites under the disconnector go to above the 3 left side cbs.

Your drawing is fine - just the brown and white wires entering the power meters are the other way around. White entering the left terminal and brown entering the right terminal. Everything else matches up.

The black bar along the cbs just appears to join all the cables across which I find odd.
All 3 live power cables?? This will all installed by the authorised national electricity company here, UTE, to their standards.


Yes the group of white wires under the disconnector go above to the 3 cbs in the same sequence also. Left to right.

 

[marconi]

Only if you feel safe to do so - would you measure and report the voltages at each of the top three terminals ( 1, 3, 5) of the disconnector to earth and then do the same for the corresponding bottom 3 terminals ( 2 , 4 ,6 )? Ac voltage and a scale to read at least 230V.

 

[Yonny24]

Only if you feel safe to do so - would you measure and report the voltages at each of the top three terminals ( 1, 3, 5) of the disconnector to earth and then do the same for the corresponding bottom 3 terminals ( 2 , 4 ,6 )? Ac voltage and a scale to read at least 230V.

Will do.
Yes I feel safe to do this. I've worked with valve amps, 500v transformers for power outputs and high amperage power supplies for valve heaters etc, and 400+v caps for years. These caps pack a punch even when disconnected. I know what it's like to get a shock and not pleasant (or safe). A charged disconnected cap can cause a lot of pain.
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Only if you feel safe to do so - would you measure and report the voltages at each of the top three terminals ( 1, 3, 5) of the disconnector to earth and then do the same for the corresponding bottom 3 terminals ( 2 , 4 ,6 )? Ac voltage and a scale to read at least 230V.

1 (top 1st terminal) - 258
3 (top 2nd terminal) - 28
5 (top 3rd terminal) - 240

2 (bottom 1st terminal) - 214
4 (bottom 2nd terminal) - 26
6 (bottom 3rd terminal) - 238

All measured to ground.

 

[marconi]

Thank you.
If 2, 4 and 6 out of the disconnector were indeed linked together by the black bar above the cbs then the voltage would be the same on each - which is not the case.

So to check further please measure between each of the top terminals of the 5 cbs to earth and then do the same for the bottom terminals to earth.

 

[Yonny24]

Thank you.
If 2, 4 and 6 out of the disconnector were indeed linked together by the black bar above the cbs then the voltage would be the same on each - which is not the case.

So to check further please measure between each of the top terminals of the 5 cbs to earth and then do the same for the bottom terminals to earth.

This may shed some light on the set up and function of the bus now.

Top CBS
1-202
2-24
3-224
4-202
5-24

Bottom CBS
1-202
2-24
3-224
4-202
5-24

 

[marconi]

Yes that I think has resolved much.

At you convenience could you measure at the disconnector the voltage between:

a. 1 and 2, then between 3 and 4 and lastly 5 and 6 ie: across the poles of the disconnector. Why? Because you measured 258V at 1 and 214V at 3 which indicates to me a problem with this pair of contacts - so we will check them all.

b. 1 and 3 to establish you have a 3 phase supply ( 1 to 3 will be 230V ish) or a split phase supply ( 1 to 3 will be 460V ish) - I am pretty sure it is a three phase supply with one line earthed to produce L1, L2 and N (L3 earthed) all phased 120 degrees apart.

The evidence from the voltage readings suggests to me how the panel is wired which I will now draw out.

 

[Yonny24]

ah wait think my scribbles of the voltage of 1 was wrong - let me just check.

my apologies - running up and down in between work tasks
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ok that is odd. Not sure why I measured them so differently before. Washing machine is on now. This should have no relevance unless there is an issue somewhere. I'll test again later

Here goes again sorry: (this makes more sense)

1 (top 1st terminal) - 208
3 (top 2nd terminal) - 24
5 (top 3rd terminal) - 230

2 (bottom 1st terminal) - 208
4 (bottom 2nd terminal) - 24
6 (bottom 3rd terminal) - 230

Top CBS
1-208
2-24
3-230
4-208
5-24

Bottom CBS
1-208
2-24
3-230
4-208
5-24

 

[marconi]

The UFH heating is cleverly connected across L1, L2 and N as shown in the diagram below. The black bar above the 5 cbs confused me; the voltage measurements clarified the situation.

Sometime please tell me L1 to L2 voltage. I am pretty sure you have a 3 phase supply arranged as I have drawn.

Otherwise I would swap the contactors for silent ones. Solid state switches can fail short-circuit which would not be a good thing so don't fit them. They also need substantial heatsinks and ventilation around these because they would get too hot without. If it was me I'd buy silent contactors. The three sets of UFH are each protected by a 20A cb. A 32A contactor is beefy enough to carry up to 20A 'all day long' and be more reliable than one rated close to 20A. Space the power meters and contactors apart so that there is some air movement and one does not warm the other.

Thank you for your patience!



Marconi