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Thanks for the replies everyone. I spoke to the manufacturer of the UPS and they were of the opinion that there was no necessity for an EPO, despite the fact that they promote the feature on their devices of this class. In fact, they suggested that they had never seen the feature used at all...

Hi All, I wonder if anyone could advise on the requirement for an Emergency Power Off (EPO) switch in my application? I have a small IT system, consisting of a few PCs, network switches and the like installed in a 19" rack. There is a rack-mount uninterruptible power supply (UPS) rated at 3KVA...

Thanks again to all you guys - I knew I'd come to the right place! Just one more question: Do you think it would be possible for me to get a PCB designed that would integrate the functions of the splitter, combiner and variable attenuators into one assembly?

Peter - Thanks, you have pretty much described exactly what I had in mind - even down to the 30dB fixed attenuators. Now either we're both crazy or I'm on the right track! I'm a bit concerned that all the components I come across on the Internet are intended for 0.8-2.0Ghz or more - does anyone...

Thanks Peter! There are between 10 and 32 radios per installation that have to "see" each other. Their maximum output power is 100W and various models cover the frequency range 1Mhz to 500Mhz. Do you think I could do without the circulator altogether? I just wasn't sure how to stop the...

Yes, my application has high-powered radios all transmitting/recieving on different frequencies at the same time. The reason I put a circulator in was to stop the "recieved" signal from being re-injected into the "transmit" path - is that the right thing to do?

Right - empty paint cans! Did you take a look at the diagram? What do you think?

Thanks VE1BLL, but how do I get the dynamic variable element between any two points this way? For instance, if I need (simultaneously) 120db between radio A and B, but 100db between A and C, and 150db between B and C, I don't see how I could do it using the method you suggest (but I could...

I've drawn a quick sketch of what I now think I need to do, I'd appreciate it if someone could take a look and tell me where I'm going wrong! It's one "node" of a 4-radio system. It would be nice if there was a way of building up to larger systems using a modular approach, but I'm not sure...

Thankyou for your suggestions, chaps - which to be honest only some of which I understand! There are a number of test sets, with 10 to 32 radios per set. The radio frequencies are in the range of 1Mhz to 500Mhz, so a flat response across this range would be preferrable. I wounder if I could...

Hiya, This is really outside my area, so I'm hoping you guys can come up trumps for me. I have a project where I need to connect a number of radios together via cables (for training purposes they are not allowed to actually transmit over air to each other). Now, I'd be quite happy connecting...

Scotty, Thanks for your reply. Perhaps my question was too general. Our normal operations involve low-voltage power installations, audio and data comms. These are not in any special conditions (such as mines or explosive atmospheres). The 16th Edition has a list of referenced standards and of...

Hi, Having waded through a number of standards, I was wondering if anyone had a definitive list (or link to such) of the statutory (ie legal) requirements that apply when installing cabling (and equipment) in the UK? Obviously BS7671, the 16th Edition Wiring Regulations apply and are...

Hi Scotty, Thanks for the prompt reply! Each of the PSUs are effectively generator replacements, suppling power to parked vehicles in place of an external generator. Regards, dK

We are currently designing a power supply enclosure for external use. It will be powered from a 64A 230V 50Hz AC, which is both MCB and RCD protected. It will contain 4 x 3kW 28V DC power supplies. The enclosure will be IP65, and will be permenently fixed outside. The 16th Edition IEE reg...

Chris, Yes, that does make sense but I think I may have found the answer. Omron make IP66 flip-covers for their DIN-size panel meters. Although it's not an ideal fit (the cover is designed for a 48x48 panel meter and my RCD is 36x48) I think it might do the trick. Thanks a lot for your...

Chris, Do you mean a complete add-on enclsoure, with the DIN module fitted inside? If so, then yes, I've used those too. Unfortunately, I can't add another box onto the front of my enclosure. Thanks anyway, daKlone.

Hi all, I have an application where I need a 35mm DIN rail module (a standard RCD) to be operated through a panel. This is not normally a problem, as I just have the 'switchy' bit protruding through the panel. On this occasion, the panel needs to be IP65 sealed. Does anyone know where I might...

Thanks guys.

Hi All, I am working on a power distribution unit that has to be used internationally, and am not an expert on the various mains supply systems used throughout the world. Does anyone have any info on the sorts of supply it's likely to face and what the differences are? Any suggestions...