Re: Correct switch and wiring


Blair
 

Tom
Please understand, I'm not being condescending - your comments make me think you're electrical background is minimal so I'll lay it out step by step.

Start by considering your booster - what is it's maximum current output? I said I assumed 5A, because you hadn't mentioned a current or a model number. Since two of your contact sets on the rotary must switch this current if you are to put the RRAmpMeter in the primary feed from the booster, that defines your current rating for the rotary.

Sketching out your needed circuit, I think you need to switch a lot more circuit points than you realize - up to 10, I think. So you need a 10P6T rotary, 5A rated. If you find one, I'll bet it's straight off the ark or some form of military special. I've never seen one in action, in 35 years in the electronics business.

That being said, one is still "available" at Digi-key, though not in stock:
http://www.digikey.ca/product-search/en?pv832=6&pv833=2&
FV=fff40011%2Cfff80062%2C1080770%2C10807ad%2C108080d%2C1080814%2C1080818%2C108085c%2C108086b%2C1080e37%2C1080e39%2C1080e3a%2C1080e44%2Cd140002%2Cd140006%2Cd140007%2Cd140009%2Cd14000a%2Cd140019%2Cd140020%2Cd140022%2Cd140023%2C1c240002&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=500

$829 - neat. Chump change for sure.

If you want a thousand, Electroswitch might must make them for you, but otherwise I would not expect to be able to order this with a predictable delivery date, so start looking for someone who has one.

To re-explain my relay solution - a single-pole 100 ma 6-position rotary energizes one DPDT relay in each position, except for the "no RRAmpMeter" position, which simply ignores the RRAmpMeter. Each DPDT relay switches the RRAmpMeter into the circuit it selects. Otherwise, the circuit for that position is in its normal configuration. Since the rotary is break-before-make, only one relay is ever energized, ensuring no shorts occur. Easy, simple to wire, maintain, and understand.

Total relay cost (ignoring sockets) on the surplus market is around $5 ea, for a total of $25 plus the rotary at around $5, for a total outlay of $30 to do what you want. Socket the relays, and the price might jump to $100. Still a whack of a lot less than "unobtainium", which is what I would call the Electroswitch offering.

Or, you can buy 5 RRAmpMeters and be done with it; again, cheaper than unobtanium, but more expensive than the relay solution. Depends on how you value your time.
I am sure someone can identify some surplus outlet or obscure supplier with a 10P6T 5A rotary in stock for peanuts - but that's not my point.
Blair

On 14/12/28 07:41, Blair & Rasa wrote:
Tom
A lot will depend on the current capability of the booster; assuming 5A maximum output, then your switch must be capable of at least that current, especially since the wiring will be quite involved, and therefore replacement of the switch should be a "rare event". Thinking about what you're asking for, I expect you may even need a 6-pole switch. A 5A, 6-pole multi-position switch is asking a lot; not sure if there's one out there, and I'd sit down before I looked at the price; it would likely be direct-solder, so you're going to have some fun there, too. Your second option is better, but still requires 5A contacts. Additionally, the ones I'm familiar with are PCB or soldered wire connections, which will be quite challenging unless you're a soldering pro. Personally, I'd be leaning towards a lighter-duty rotary switch for controlling multiple socketed 5A or 10A DPDT relays. This also offers the advantage of modular replacement of worn-out contacts, though that shouldn't be a common occurrence. Although the multiple-relay concept is more complex, you'll find that wiring it becomes quite straightforward. From what you've described, you'll need 5 DPDT 12VDC coil relays, and a 6-position non-shorting rotary. The bypass is achieved by not powering any relay. You must ensure that you purchase a break-before-make, aka non-shorting, rotary, to ensure that only one relay is ever energized at one time.

I've chosen Jameco as a representative supplier, you may have your own sources:
non-shorting switch: http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2184456_-1
socket: http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_141145_-1
relay: http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_139766_-1
Or, if you prefer to direct wire the relays, then use these: http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2093079_-1

You could also somewhat optimize your costs by using lower cost, lower current relays for the 4 districts - but your relay for switching in/out the RRAmpMeter will have to be capable of switching the full booster output.

This whole setup may or may not work for you, but I throw it out there for consideration. It is certainly how I would do what you are proposing. Whether one should or should not be switching any of this in this manner when powered up I will leave to others. I expect it wouldn't be good for the RRAmpMeter, and possibly not for the PSX4/PM42, but I don't know that for sure.

Blair Smith



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