Food dryer project

[grumpyjohn01]

Hi All, With some trepidation I am throwing this one out for comments / advice from members.
I have been asked by a customer to provide 3 phase supplies for some 'machines' that are under development by my customer.
The machines are basically cabinets for dehydrating food items , that have been designed by my customer as he has been unable to find a suitable commercial product that will meet his needs.
So far he has arrived at a test machine that has a fabricated upright steel cabinet with heating elements mounted at the rear and multiple fans at the front, drawing warm air over the food which is spread over trays stacked on a shelved trolley that is wheeled into the cabinet.
There are 3 x 3kW single phase heaters that are separately controlled by solid state relays and the fans are ELV units that are electronically controlled by a series of thermostatic probes, the idea being to maintain the correct temperature, humidity etc over the height of the unit so that the food dries evenly.
At present he has everything supplied via multiple 13A plugs connected to various sockets which may or may not be on the same circuit / phase. I have cautioned him on overloading circuits etc.
His prototype is now working (pic) and he wants to turn this into a finished appliance that will be used commercially and copied for use in his own premises.
Whilst he is taking full resposibility for the appliances themselves (compliance with relevant regs etc) I have been asked to install supplies and assist with packaging the electrical elements of the design.
I can see no problem with supplying the unit from a 5-pin 16A RCD socket as the heater elements although separately controlled will be roughly in balance (similar load) and the ELV parts will be a negligible (single phase) load in comparism.
My thoughts on packaging are that the different voltages present should be separated adequately (different enclosures,double insulation, sheathing etc) and that the steel casing should be of course adequately earthed.
Also I have thought that a 'fail safe' thermal trip operating an 'upfront' contactor might be advisable.
Any other thoughts? other than run a mile, which is kind of what I am expecting...

 

[Spoon]

Whilst he is taking full resposibility for the appliances themselves (compliance with relevant regs etc) I have been asked to install supplies and assist with packaging the electrical elements of the design

Also I have thought that a 'fail safe' thermal trip operating an 'upfront' contactor might be advisable.

I don't quite understand your roll in this. In one part you are saying the customer has made sure the machine is all compliant and then then next you are suggesting adding safety equipment to the machine.

If you are just responsible for adding power for the machines then all is well and good, and pretty straight forward.
If you are adding safety components to the machine then things get a lot more complicated.

 

[telectrix]

provide him with a 5 pin 3p socket (16A) and that's it. let him worry about anything plugged in.

 

[grumpyjohn01]

I don't quite understand your roll in this. In one part you are saying the customer has made sure the machine is all compliant and then then next you are suggesting adding safety equipment to the machine.

If you are just responsible for adding power for the machines then all is well and good, and pretty straight forward.
If you are adding safety components to the machine then things get a lot more complicated.

I have done all of the electrical installations for this customer for a while and he has asked me for help with this. I appreciate what you are saying and my lack of knowledge on product standards and so on is notable..He has said that he will take responsibility for the final product but wants guidance on how to provide as safe an appliance as possible, so I am doing my best to help him. He will go ahead with this project regardless I am sure, but I am interested and wish to assist where I can. I understand the pitfalls of compliance with the various regs that may apply to a new 'product' . Do you think this requires a specialist engineer / consultant to be sure?

 

[grumpyjohn01]

provide him with a 5 pin 3p socket (16A) and that's it. let him worry about anything plugged in.

Yes, this was my initial thought so as to avoid any liability, however the customer is a good guy and has given me plenty of interesting work in the past so I am keen to help him get this off the ground. I am pretty sure he won't follow any recognised route to product compliance but will assume full responsibility for the operation of the machines once completed. I am just keen to provide as much help as I can to make them as safe as can be under the circumstances.

 

[Spoon]

I have done all of the electrical installations for this customer for a while and he has asked me for help with this. I appreciate what you are saying and my lack of knowledge on product standards and so on is notable..He has said that he will take responsibility for the final product but wants guidance on how to provide as safe an appliance as possible, so I am doing my best to help him. He will go ahead with this project regardless I am sure, but I am interested and wish to assist where I can. I understand the pitfalls of compliance with the various regs that may apply to a new 'product' . Do you think this requires a specialist engineer / consultant to be sure?

I understand that you are interested, as I would be, but there is more to it than just regs. There are all the safety paperwork side of it as well.

You just need input from someone who can come and see the machine and chat to you about all the different aspects of the electrical side.

 

[The Ghost]

As above supply the three phase connector for him. Consideration of his equipment is mission creep and complicates your brief to put in a supply. No doubt there will be additional protection?

 

[Spoon]

I am pretty sure he won't follow any recognised route to product compliance but will assume full responsibility for the operation of the machines once completed

Really........
And you want to be involved in someone who doesn't want to do the job properly and has no regards for the safety of others?

 

[grumpyjohn01]

[QUOTE="Spoon, post: 1441985, member: 17530"

You just need input from someone who can come and see the machine and chat to you about all the different aspects of the electrical side.[/QUOTE]
Yes, exactly that! Is there anybody out there who would do this?

 

[grumpyjohn01]

Really........
And you want to be involved in someone who doesn't want to do the job properly and has no regards for the safety of others?

He does want to do the job 'properly' but the costs of going down a 'complete approval' route for this small scale product would likely be prohibitive. This won't be a commercially available product that can be purchased, just for use in his own premises.

 

[grumpyjohn01]

So then, does anybody know or can recommend somebody who could assist with the electrical compliance aspect of this project? Somebody that is who would not expect the kind of remuneration that a mainstream appliance manufacturer would provide!

 

[Spoon]

He does want to do the job 'properly' but the costs of going down a 'complete approval' route for this small scale product would likely be prohibitive. This won't be a commercially available product that can be purchased, just for use in his own premises.

Sorry for my generalisation comment. The above makes it more clear. I will alter my comment in post #8 accordingly... "And you want to be involved in someone who doesn't want to do the job properly and has no regards for the safety of his workers?

 

[grumpyjohn01]

Sorry for my generalisation comment. The above makes it more clear. I will alter my comment in post #8 accordingly... "And you want to be involved in someone who doesn't want to do the job properly and has no regards for the safety of his workers?

To be absolutely clear. He does have regard for safety.
I am looking for a way to ensure safety to the highest possible standard without going down the road of costly product approval that would be undertaken for a mainstream commercially available product. I am sure there must be a way to practically comply with the most important issues without doing this . For instance how do developers guarantee the safety of prototypes under development without product approval at every stage?

 

[Spoon]

I am looking for a way to ensure safety to the highest possible standard without going down the road of costly product approval that would be undertaken for a mainstream commercially available product.

Ok mate, so It might be the way I'm reading it or the way you are putting info across but the safety standards have to be the same for the machine, regardless of if it's his workers using them or if the machine was sold to another company.

 

[Spoon]

For instance how do developers guarantee the safety of prototypes under development without product approval at every stage?

By doing risk assessments and making sure the components and operating procedures are all correct.