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Non Priority Shower Unit explained

Buford T Justice

I have an old non priority shower unit that I'm looking to figure out.

I know what the MCB's are and the ESN240B's are but I'm not sure what the two on the right are, the Doepke RLR1's

Can someone explain what they are and their purpose please?

Larger image https://postimg.cc/nsqP8Ggt

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Treseemme.

They're current sensing relays

Each shower is wired through one and when shower is turned on they break the supply to the other showers contactor coil

zg3409

The way these systems work is:

Both showers get power all the time.
Both large middle contactor's are on 24/7/365

Once any shower draws any significant amount of power its current sensor (one of the 2 on the right) detects one of the shower is on. Based on this it powers off the other shower (by powering off its contactor) until the person turns off the shower later.

The Hager contactor's tend to give trouble as they overheat and melt inside as they are on always and there are 2 right next to each other in an enclosure. If you replace them the new ones fail too. Ideally they need lots of air around each contactor and not next to each other.

When you say figure out, what are you trying to do? These are high power and a fire risk due to heavy loads. What would you like to achieve?

Buford T Justice

I'm looking to see if I can repurpose some things that I have for my campervan build (see sig).

As per the crude diagram below, I will have two 240 sources of power for my van, the first being an inverter running off 12v batteries and the second being shore power plugin.

Under normal circumstances (ie no shore power) the inverter will provide power to the sockets. However, if I plug in shore power, I want the contactor to switch over automatically to use the shore power to provide the power and disconnect the shore power. Bearing in mind this is for a campervan, there won't be massive loads running through this. At the moment it's only a fridge

I know I can get a Schneider contactor to do this, but I'm hoping to re-use things that I already have.

zg3409

Buford T Justice wrote: »

I'm looking to see if I can repurpose some things that I have for my campervan build (see sig).

As per the crude diagram below, I will have two 240 sources of power for my van, the first being an inverter running off 12v batteries and the second being shore power plugin.

Under normal circumstances (ie no shore power) the inverter will provide power to the sockets. However, if I plug in shore power, I want the contactor to switch over automatically to use the shore power to provide the power and disconnect the shore power. Bearing in mind this is for a campervan, there won't be massive loads running through this. At the moment it's only a fridge

I know I can get a Schneider contactor to do this, but I'm hoping to re-use things that I already have.

I believe to meet the regulations you need either a mechanical switch to change supplies or an electrically and mechanically interlocked contactor. The contactor's above won't do what you need. A simple 2 position 2 pole switch would be best. If you are looking at automated chageover you need to be 100% sure there is no chance you will supply power from your inverter system back to the caravan site in case of any fault or during a power cut. This can kill someone else nearby. Buy a proper 2 contactor mechanically interlocked system with auxiliary contacts if you need this set up, like this but with 240v AC contacts and an AC or DC coil as you need:

https://ie.rs-online.com/web/p/contactors/6097432/?cm_mmc=IE-PLA-DS3A-_-google-_-CSS_IE_EN_Automation_%26_Control_Gear_Whoop_HI-_-(IE:Whoop!)+Contactors+(2)-_-6097432&matchtype=&pla-478525856838&gclid=Cj0KCQiAlsv_BRDtARIsAHMGVSbZ-KBUl6GikaBQXIyGlJRYjYjApNGZJ-6bIPZM6HwmgIt0F_9lGncaAnROEALw_wcB&gclsrc=aw.ds

https://www.youtube.com/watch?v=PnlVNb2I524

Buford T Justice

What about this?
https://ie.rs-online.com/web/p/contactors/7912935

zg3409

Buford T Justice wrote: »

What about this?
https://ie.rs-online.com/web/p/contactors/7912935

You need 2 contacts mechanically connected so they both never be in at the sane time. You also need normally closed auxiliary contacts, . These are wired so electrically both can't be on at the same. These rules are to protect others.

Treseemme.

zg3409 wrote: »

The way these systems work is:

Both showers get power all the time.
Both large middle contactor's are on 24/7/365

Once any shower draws any significant amount of power its current sensor (one of the 2 on the right) detects one of the shower is on. Based on this it powers off the other shower (by powering off its contactor) until the person turns off the shower later.

The Hager contactor's tend to give trouble as they overheat and melt inside as they are on always and there are 2 right next to each other in an enclosure. If you replace them the new ones fail too. Ideally they need lots of air around each contactor and not next to each other.

When you say figure out, what are you trying to do? These are high power and a fire risk due to heavy loads. What would you like to achieve?

That was the weird thing about those units

The n/c contact on the sensing relay and the main contactors permanently energized

Not the greatest design

Treseemme.

The Rcd is or should be the isolator for the board

May not be obvious there

Buford T Justice

zg3409 wrote: »

You need 2 contacts mechanically connected so they both never be in at the sane time. You also need normally closed auxiliary contacts, . These are wired so electrically both can't be on at the same. These rules are to protect others.

Just trying to understand. Why would the contactor that I posted not work? I've seen a few people use them in their own installs. If it's switching both contacts when energised then there'd be no risk of the inverter back feeding the shore power in case of a power failure on the shore power since it'd be routing to the onboard power. It'd be done in the case of four in and two out. Perhaps my diagram is insufficient to describe this.