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Discuss Current sensing breaker 5A-16A - Caravan application in the Electrical Forum area at ElectriciansForums.net

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Hi folks, there’s a thread running on a caravan forum I’m on so I thought I’d ask on here where the experts live!

Caravan EHU supplies vary between 6A, 10A and 16A. So one of the chaps who regularly goes abroad where there are 6A supplies gets ticked off with the wife tripping the bollard - usually late at night when there is no-one around to re-set it.

He’s asked if there is anything on the market that would monitor the current being drawn, and open the supply before tripping the bollard breaker.

Seems there is in the USA but nothing caravan specific in the UK.

There’s clearly current sensing breakers available with various disconnection times and sensitivity, I’m guessing it would need some sort of control circuit to stop the contact from chattering as soon as it opened and the current dropped - then it would re-make etc etc

So if anyone’s got any (helpful) ideas it would be great to hear them, he is not going to connect anything himself by the way.
 
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PEG

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Mentor
Arms
Esteemed
Hi,at the lower end,discrimination will be an issue.
(that is nowt to do with cheap caravans and foreigners...)

It is possible to over load most breakers,so generally,just know the limitations. Post it notes,or locking the wife's stick welder,in a cupboard,might work.

What equipment is used? Are there any items which cycle,or vary their current requirement?

If you need more than 500 watts for a milk heater and some lamps....you're havin' a posher holiday than me...;)
 

Lucien Nunes

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Mentor
Arms
Esteemed
You could use an adjustable current sensing relay such as this:
Current monitoring relay Selec 900CPR-1-1-BL-230V-CE - https://www.automation24.co.uk/current-monitoring-relay-selec-900cpr-1-1-bl-230v-ce or one of the many similar devices. Whatever you use, it ought to be true-RMS sensing, as MCBs respond to the RMS current value using resistive heaters. You would have to set it to the worst-case MCB curve with a compromise delay, as it won't track the actual curve.

The monitoring relay would have to operate a contactor or power relay to disconnect the caravan loads, or at least the ones capable of causing an overload (e.g. the charger and 230V lighting could stay on). To prevent the cycling you describe, you could use a manual reset button to latch the contactor in, until an overcurrent releases it. However, it would have to be manually reset after a supply loss. Using the monitoring relay to trigger a shunt-tripping actuator on an MCB would give you a manual reset that remains engaged through a supply loss.

Alternatively, the recovery time on the relay I linked can be set to 99 seconds, giving you time to switch off the offending overload before it re-energises.

I've used a much simpler method in my boat. I have a couple of MCBs that can be switched in optionally, on which I have adjusted the tripping current to be about 10% light. Because the curve will match that of the shoreline MCB fairly well, I haven't had to make it unduly sensitive or fast, just enough of a margin to cover any temperature difference if the bollard MCB is in the sun and my MCB isn't. So far I have had about five incidents, on a couple of different shoreline supplies, and my MCB has opened first each time. Obviously this method does not give me the luxury of tripping off only part of the load being monitored.
 
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  • #4
Thanks Lucien, it’s become quite an interesting little project/idea - not sure if anything will come of it but I’ll post you’re suggestion, many thanks
 

DPG

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Arms
Esteemed
Advent Win
Thanks Lucien, it’s become quite an interesting little project/idea - not sure if anything will come of it but I’ll post you’re suggestion, many thanks
Don't forget to give him credit for it.
 
  • Thread Starter Thread Starter
  • #6
I think that’s the annoying thing is that it’s not hard to think twice but to generalise it seems that the wives tend not to judging by the views of the majority on the caravan talk forum!
Alde central heating does have load sensing and will shut down the heating at a set load, it’s usually microwave, kettle and hairdryer issues!

I did say the post wasn’t from me by the way
 
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