Immersion Heater - PV electricity

[echase]

RS Components stock a Crydom cover but can't say if it fits that particular SSR model as I don't use it. They list a pad but have not had any in stock for months.

I'd be very surprised if it did not have 1000s of volts of input to output isolation as all their simpler SSRs do. Look up the datasheet for the answers.

 

[sharpener]

Thanks for that. Inie meanie has also been generous enough to provide some answers off-line too.

Look up the datasheet for the answers.

If only it were that easy!

The data sheet says 2500V max signal to load but says nothing about how this is achieved. If I knew what the input configuration was - opto-coupler like the LPCV series? - I could then guesstimate how it would behave and whether I need to protect against voltages <0 and >10. The control input is only specified as drawing 4 mA at 5V, which is not very helpful when you need 10V to turn it on fully. I had hoped to find an application note on the Crydom web site with more details but there is nothing useful there, hence my previous posting.


BTW pmcalli, the analogue multiplier power measurement circuit I described in posting #354 is now working a treat.

 

[suntrap]

If you just put an 11V zener diode across the input, it will protect against both overvoltage and wrong polarity (assuming your source impedance is high enough that the diode can dissipate the excess power) and as it costs a few pence I'd just do that and not worry about the finer details.

 

[sharpener]

Good thinking. Actually I found a 4V7 and a 6V2 in my scrap bin so have put them in series across the feedback resistor in the driver amp, this reduces the power drain and is a bit kinder all round.

 

[thushar]

Just found this 27" 2 1/4" BSP thread 1 kW immersion heater in ebay -
1 kw / 1000 W 27" Immersion Heater - Use Spare Solar Panels Power For Heating | eBay

Hope that will help

 

[bradburts]

A 2 kW immersion heater 2kW Immersion Heater and IMM01 - 2kW Immersion Heater Power Halver and Power Reducer would be as cheap and may prove more flexiable.
I imagine that its just a diode, perhaps some filtering. Its CE marked (for what that is worth) & has a thermal cut out.
You could easily add a relay to switch between 1kW and 2kW

EDIT: Removed link, it won't work!

 

[suntrap]

Interesting thing, that power halver, though I'd wait to see how much the 3kW one is as it would mean the standard/existing element could be used.

Those marine heaters are short (for fitting horizontally in the bottom of the tank) and it doesn't say they're "incolloy".

 

[bradburts]

Yes, the second immersion link is no good.
Was scanning & saw 28 & assumed inches.......
I will remove the link if possible.

 

[pmcalli]

Thanks for that. Inie meanie has also been generous enough to provide some answers off-line too.



If only it were that easy!

The data sheet says 2500V max signal to load but says nothing about how this is achieved. If I knew what the input configuration was - opto-coupler like the LPCV series? - I could then guesstimate how it would behave and whether I need to protect against voltages <0 and >10. The control input is only specified as drawing 4 mA at 5V, which is not very helpful when you need 10V to turn it on fully. I had hoped to find an application note on the Crydom web site with more details but there is nothing useful there, hence my previous posting.


BTW pmcalli, the analogue multiplier power measurement circuit I described in posting #354 is now working a treat.

I have now completed testing of meter behaviour and have very bad news for you. The meter measures true power and your analog multiplier measures apparent power so you will be feeding back uneccesary power. I have now tested using a synchronous demodulator and it correctly follows true power as measured by the meter. The other advantage is the circuit is unchanged whether you use one ct on composite meter tail or two cts on seperate meter tails.

 

[JohnBoyZ]

I have now completed testing of meter behaviour and have very bad news for you. The meter measures true power and your analog multiplier measures apparent power so you will be feeding back uneccesary power. I have now tested using a synchronous demodulator and it correctly follows true power as measured by the meter. The other advantage is the circuit is unchanged whether you use one ct on composite meter tail or two cts on seperate meter tails.

That sounds very interesting, especially if it can give accurate readings with a single ct on the combined meter tails and presumably with import/export direction indication. Are you likely to be posting a circuit diagram as I for one would be very interested to try it out?

 

[pmcalli]

That sounds very interesting, especially if it can give accurate readings with a single ct on the combined meter tails and presumably with import/export direction indication. Are you likely to be posting a circuit diagram as I for one would be very interested to try it out?

Yes it is direction sensitive. I have been testing it by running it at same time as my original and it shows the power factor error. I haven't been able to test it running the immersion heater yet as I haven't been at home when the suns out. before posting I would like to run a proper test to ensure there is no forward meter creep on all loads. If friday afternoon or the weekend is sunny i will do the tests and post the circuit. If you want a preliminary look send me a private post with your email address.

 

[pmcalli]

Can anyone who has used the Crydom 10PCV2425 controller or similar confirm that they are optically coupled so there is complete isolation between the input and output sides? Also, what current does the control input draw at 10V and what are the voltage limits? Some circuits published here seem not to have any overvoltage/reverse voltage protection for the control input!

Lastly can anyone point me at a supplier for the Crydom polycarbonate terminal cover (pictured earlier) and heat sink pad? Farnell have a good price for the controller but don't seem to stock the accessories.

TIA

the cover RS supply fits nearly all the crydom models. Don't bother with the heat-sink pad its runs stone cold without it. I have been using the MCPC2450C because its twice the current rating and 54.36 instead of 72.20 from RS

 

[inie meanie]

the cover RS supply fits nearly all the crydom models. Don't bother with the heat-sink pad its runs stone cold without it. I have been using the MCPC2450C because its twice the current rating and 54.36 instead of 72.20 from RS

Anybody know what the difference between the 10PCV2450 and the MCPC2450C is? They look the same apart from the price.

 

[pmcalli]

Anybody know what the difference between the 10PCV2450 and the MCPC2450C is? They look the same apart from the price.

The MCPC2450C is 50 Amps instead of 25 it has an enable i/p and you have to supply the voltage for the analogue part. I tie the enable and the Vd to 15V. It also has an LED whose brightness indicates control level. It has a better spec for control impedance and there is a lot more max rating specified. data sheet is on RS site. I have controllers running with both types. The control voltage can go to max supply so protection zener is not required but I still fit one as it stops the integrator saturating. Cover fits both

 

[DickiePhitt]

I've been out of this thread for a few months while I followed the Nanode-based control solution that was discussed in earlier posts. I have done the assembly and mimicking and am about to connect to the 5V version of the same controller[FONT=Verdana, Arial, Helvetica, sans-serif] - MCPC2450A[/FONT]

pmcalli, do you have the output filtered? If so what have you used?