Can anyone (EEs) interpret this electrical safety warning?

[dullard]

I'm hoping some electrician or electrical engineer could help me. I could call the manufacturer and be on hold for 1 hour - but then I have to suffer through weekly calls for the next 3 months with people checking up (I've done this in the past and I really would like to avoid it). I figure this is a long shot posting here though.

I've got this SRA-01 board. The instructions are listed here. Basically there are 9 slots in the board for some solid state relays. 3 of these relays each will have 0.5A of DC current at 24 Volts running through them (each running from 5V, 20 mA current from the board). I need to add 3 relays with 3A of AC current at 120 V running through them (each running from 5V, 20 mA current from the board).

There is a warning in the instructions that says "Do not place non-hazardous I/O modules next to hazardous I/O modules." The 120 V modules are considered hazardous if I understand correctly. So does that warning mean I need to leave one slot blank between the relays or does that mean I need a whole new SRA-01 board (basically what is the definition of "next")? I just want to know if I will fry the board if I use both types on the same board with 2 slots of space in between.

 

[43st]

You need two boards. One rated at 500mA (the one you spec.), the other rated at 3A. The spec you list has a max 610mA rating so you better not put a 3A device on it.

You can always control both boards from one relay closure.

 

[dullard]

Originally posted by: Thera
You need two boards. One rated at 500mA (the one you spec.), the other rated at 3A. The spec you list has a max 610mA rating so you better not put a 3A device on it.

You can always control both boards from one relay closure.

Thanks for your reply.

Sorry to be a bit confusing as I know very little about these things. The relays each take 20 mA drive current from the board. So with 6 slots filled the max is 120 mA drive current running through the board. The load current (running through the relays) of 3A is completely different from the drive current.

 

[43st]

Ok... I looked at it a bit further. My last reply was in response to the spec sheet.

I thought you were putting 120VAC/VDC directly into the controller board, my mistake. I understand your confusion now, it's just worded poorly. They're trying to prevent an arc from one module to the next so I'd imagine that's why they suggest insulation ( >BASIC INSULATION, 300V, CAT II, pollution degree 2). So... Use the insulation and you can place the modules together.

I'd suggest you give them a call if you have any questions. You'd be surprised how many "pros" call manufactures with installation questions.