Relay wiring help needed

[bernardgreen]

RF Lighting's advice is correct if it is a fake. ( It probably is a fake )

These fake AC coil relays have been known to catch fire when the coil is energised for more than a few seconds. ( the magnetic core is solid steel instead of laminated.and heats up on eddy currents )

The real item can be bought from places like Farnell

http://uk.farnell.com/omron-industr...0/power-relay-dpdt-240vac-10a-plug/dp/9862064

There are other sources of similar relays.

I would have similar concerns about that WillHi controller's authenticity.

 

[AtariBoy]

Okay, thanks for the advice, would Maplin supply something safe?

 

[ban-all-sheds]

How do I work out what to wire where on the relay socket?

You could look at the wiring diagram you have:

[/URL]

And/or you could read the post where that question has already been answered:

The pic of the relay however. A1 is switched live in from the controller. A2 is your neutral.
Then 11 and 21 are live and neutral in, and 14 and 24 live and neutral out to the load.

And/or you could look at the answer from Gareth:

Untitled

• GarethW
• 26 Aug 2014
• 1

There's not much point you asking questions if you aren't going to read the answers and then just ask them again.

I know you say that you don't have much electronics knowledge, but that is a shortcoming for you to resolve, not for people here to compensate for.

You must, you absolutely MUST, understand what you are doing. You must not, under any circumstances, start following instructions to 'insert this wire in that hole' without a full and genuine understanding of why.

I have little electronic knowledge

I have little knowledge of boat handling and navigation.

I therefore do not think that it would be sensible for me to have a bash at sailing on the basis of following instructions from an internet forum which I did not understand.

Connecting these items up is really pretty trivial, and if you cannot understand how to do it then cobbling together your own control system for this fridge is not for you. It really is that simple.

 

[AtariBoy]

I have a also got one of these (or very similar) to control everything:
http://www.ebay.co.uk/itm/181106804925[/QUOTE]
" Item location: Shenzhen, China" I hope you aren't going to have it in the house, or in any other building you care about.

There's a reason why that item is £9.97 when these range from £38 to over £800, and it's not entirely profiteering by RS.

Okay, whilst we are reviewing components, could you point me to the correct RS version please.

 

[ban-all-sheds]

No.

See above.

I cannot stress too strongly that you MUST be able to do this yourself.

You MUST know how the components work, how the overall solution works, how to connect it up.

You MUST understand your requirements well enough to identify the components you need.


No lesser level of knowledge is remotely acceptable.

 

[stem]

it's for a cheese curing fridge project

You don't give any details of the fridge. Is it domestic? industrial? If it is compressor driven, the start up current can be 4 to 6 times higher than the stated running current. This is important as the relay contacts need to be up to the starting load.

For example, a small domestic fridge rated at 350W will have a running current of approximately 1.5A but would blow a 5A fuse because it has a high starting current. Hence why fridges come with 13A fuses.

 

[ban-all-sheds]

Plus are we to assume that you want to run this fridge at a higher temperature than it can normally be set to, e.g. around 10°C?

If so, have you looked into what being turned on and off all the time will do to the fridge? Will cycling the compressor so frequently knacker it? Will any auto-defrost work?

And don't you need ventilation and humidity control for curing/aging cheese properly? Is being shut in a sealed box OK?

 

[JohnW2]

The relay from eBay: ... The description is "Pro 220V Coil Power Relay 10A DPDT " which means The coil needs 220volts to energise

That's certainly what one might think. However, as others have noted, the description says that it has a 12V DC coil !

As others have commented, at £2.49, including free shipping (not to mention the cost of shipping from China in the first place), this item is almost certainly a fake - and therefore quite probably will be unsatisfactory or unreliable, if not also dangerous.

Kind Regards, John

 

[JohnW2]

If so, have you looked into what being turned on and off all the time will do to the fridge? Will cycling the compressor so frequently knacker it?

Interesting question. However, 'inverter fridges' aside, does a fridges's thermostat do anything different from switching the power to the compressor? If not, then I'm not sure that running it at an unusually high temperature would involve any more compressor on/off cycles than normal, would it (perhaps even less)?

Will any auto-defrost work?

At the sort of temperatures the OP is probably aiming for, I suspect there will be no frost!

And don't you need ventilation and humidity control for curing/aging cheese properly? Is being shut in a sealed box OK?

Another good question. I thought that the optimum for cheese was around 10-15 °C (which may be achievable with some unmodified domestic fridges) and high humidity (70%-80%).

Kind Regards, John

 

[ban-all-sheds]

I'm not sure that running it at an unusually high temperature would involve any more compressor on/off cycles than normal, would it (perhaps even less)?

I suspect more, as the fridge will still be governed by its own internal thermostat.

It's expecting to run the compressor until it gets down to temperature, which it will maintain quite well because of all the insulation, and the compressor will thereafter run intermittently as required. Mine had a fan in which runs independently of the compressor to distribute air around inside for temperature uniformity.

If an external control is used to keep it at 10°, then that will kick in and out all the time.

And having written that I'm not sure any more that it would be on & off more than normal.

At the sort of temperatures the OP is probably aiming for, I suspect there will be no frost!

The bits which get cold will get just as cold as normal, only less often.

No fridge runs at freezing point, so if they need defrost cycles at 6° they'll probably need them at 10°.

Another good question. I thought that the optimum for cheese was around 10-15 °C (which may be achievable with some unmodified domestic fridges) and high humidity (70%-80%).

Will he be able to get anywhere near that humidity?

 

[JohnW2]

I'm not sure that running it at an unusually high temperature would involve any more compressor on/off cycles than normal, would it (perhaps even less)?

I suspect more, as the fridge will still be governed by its own internal thermostat.

The temperature inside he fridge will surely never get low enough for the internal thermostat to open, will it? (i.e. that thermostat will be permanently closed, all control of the compressor being by the additional/external thermostat)

At the sort of temperatures the OP is probably aiming for, I suspect there will be no frost!

The bits which get cold will get just as cold as normal, only less often. No fridge runs at freezing point, so if they need defrost cycles at 6° they'll probably need them at 10°.

Maybe - what you say does make sense. However, I don't recall ever having seen any frost/ice within a wine fridge, which is probably about the same temp as we're talking about.

Another good question. I thought that the optimum for cheese was around 10-15 °C (which may be achievable with some unmodified domestic fridges) and high humidity (70%-80%).

Will he be able to get anywhere near that humidity?

You tell me! If your thoughts about frosting are correct, that might sabotage most attempts to get the humidity high!

Kind Regards, John

 

[ban-all-sheds]

The temperature inside he fridge will surely never get low enough for the internal thermostat to open, will it? (i.e. that thermostat will be permanently closed, all control of the compressor being by the additional/external thermostat)

Yes - that was what concerned me.

The external controls will be trying to maintain the fridge at a higher temperature than it naturally wants to be. As you say, the internal thermostat will always be closed, as soon as the external one kicks in the fridge will start up, and begin aggressively lowering the temperature, so soon the external one will open, and so on. Don't know what hysteresis the OP would program in though.

Maybe - what you say does make sense. However, I don't recall ever having seen any frost/ice within a wine fridge, which is probably about the same temp as we're talking about.

I don't see any in my fridge, but it does have a drainage system which leads to an evaporator dish on top of the compressor. It's my understanding that frost-free appliances just keep any frost outside of the main compartments.

 

[JohnW2]

Yes - that was what concerned me. ... The external controls will be trying to maintain the fridge at a higher temperature than it naturally wants to be. As you say, the internal thermostat will always be closed, as soon as the external one kicks in the fridge will start up, and begin aggressively lowering the temperature, so soon the external one will open, and so on. Don't know what hysteresis the OP would program in though.

That's the point, isn't it? In both cases (internal and external control) the frequency of the cycling will be primarily determined by the hysteresis of the thermostat, not the controlled temperature - so, without knowing the characteristics (or programming, in the case of the electronic one) of the two thermostats, one can't know which would result in more frequent cycling.

Kind Regards, John

 

[AtariBoy]

I need to pick this up again, could I ask those that WANT to help please assist, thank you to those who have advised I don't continue, duily noted although I still want to try and resolve this.

This is where I am so far:

Could someone please tell me what does where in very simple terms, (relay and relay holder have been replaced with maplin components).

Many thanks,

 

[ban-all-sheds]

FHS - you have had Gareth's diagram for almost 4 weeks.

What is it that you still do not understand? Because understanding is essential.

You must, you absolutely MUST, understand what you are doing. You must not, under any circumstances, start following instructions to 'insert this wire in that hole' without a full and genuine understanding of why.

No lesser level of knowledge is remotely acceptable.